lessonID
stringlengths 6
6
| lessonName
stringlengths 3
52
| ID
stringlengths 6
21
| content
stringlengths 10
6.57k
| media_type
stringclasses 2
values | path
stringlengths 28
76
⌀ |
|---|---|---|---|---|---|
L_0495 | consumers and decomposers | T_2867 | Decomposers ( Figure 1.2) get nutrients and energy by breaking down dead organisms and animal wastes. Through this process, decomposers release nutrients, such as carbon and nitrogen, back into the environment. These nutrients are recycled back into the ecosystem so that the producers can use them. They are passed to other organisms when they are eaten or consumed. Many of these nutrients are recycled back into the soil, so they can be taken up by the roots of plants. The stability of an ecosystem depends on the actions of the decomposers. Examples of decomposers include mushrooms on a decaying log. Bacteria in the soil are also decomposers. Imagine what would happen if there were no decomposers. Wastes and the remains of dead organisms would pile up and the nutrients within the waste and dead organisms would not be released back into the ecosystem. Producers would not have enough nutrients. The carbon and nitrogen necessary to build organic compounds, and then cells, allowing an organism to grow, would be insufficient. Other nutrients necessary for an organism to function properly would also not be sufficient. Essentially, many organisms could not exist. Examples of decomposers are (a) bacte- ria and (b) fungi. | text | null |
L_0496 | control of insects | T_2868 | Though insects can be very important, some are also considered pests. Common insect pests include: 1. 2. 3. 4. Parasitic insects, such as mosquitoes, lice, and bed bugs. Insects that transmit diseases, including mosquitoes and flies. Insects that damage structures, such as termites ( Figure 1.1). Insects that destroy crops, including locusts and weevils. Many scientists who study insects are involved in various forms of pest control. Most utilize insect-killing chemicals, but more and more rely on other methods. Ways to control insect pests are described below. | text | null |
L_0496 | control of insects | T_2869 | Biological control of pests in farming is a method of controlling pests by using other insects (or other natural predators of the pests). Biological control of insects relies on predation and parasitism. Insect predators, such as ladybugs and lacewings, consume a large number of other insects during their lifetime. If you add ladybugs to your farm or garden, they will help keep insect pests, such as aphids, under control. Aphids are among the most destructive insect pests on cultivated plants in temperate regions, so any control of these pests is beneficial. Ladybugs also consume mites, scale insects and small caterpillars. The larvae of many hoverfly species also feed upon aphids, with one larva consuming up to fifty aphids a day, which is about 1,000 in its lifetime. They also eat fruit tree spider mites and small caterpillars. Dragonflies are important predators of mosquitoes, and can be used to control this pest. Parasitic insects include insects such as wasps and flies that lay their eggs on or in the body of an insect host, which is then used as a food for developing larvae. The host is ultimately killed. Caterpillars also tend to be one likely target of parasitic wasps. | text | null |
L_0496 | control of insects | T_2870 | Chemical control of pests involves the use of insecticides. Insecticides, which are also known as pesticides, are most often used to kill insects. Insecticides are chemicals that kill insects. The U.S. spends $9 billion each year on pesticides. Disadvantages to using pesticides include human, fish, and honeybee poisonings, and the contamination of meat and dairy products. When choosing to use an insecticide, there are numerous points to consider. Negative effects of the pesticide should try to be minimized. Important questions to consider include the following. What is the chemicals success against the target pest? Will the insecticide provide the desired level of control of the pest? If the answer is no, other methods of control should be considered. Does the chemical have an impact on natural enemies of the pest? In large scale efforts to rid areas of mosquitoes, the insecticide used also killed the dragonfly. This effort removed a natural predator of the mosquito. This may be an unacceptable negative effect of using the insecticide. How susceptible is the crop to insect damage? If the crop is not heavily damaged, only minor pest control may be needed. This may affect the amount or type of insecticide used. How toxic is the chemical to the environment and humans? Some older insecticides are extremely poisonous. Keep in mind that users of these poisons have a community responsibility to minimize the contamination of the surrounding environment, as well as keeping animals, surrounding crops and humans safe. Does using the pesticide result in the development of resistance? If so, this can make additional use of the pesticide less effective. As the resistance will be passed to future generations of the insect (which is natural selection in action), this could be considered a negative side-effect of pesticide use. | text | null |
L_0497 | crustaceans | T_2871 | Crustaceans are a large group of arthropods, consisting of almost 52,000 species. The majority of crustaceans are aquatic. Some live in the ocean, while others live in fresh water. A few groups have adapted to living on land, such as land crabs, hermit crabs, and woodlice ( Figure 1.1). Crustaceans are among the most successful animals, and can be considered the dominant aquatic animals. Though small, crustaceans are numerous enough to be the main source of energy for large ocean mammals. They are found as much in the oceans as insects are on land. | text | null |
L_0497 | crustaceans | T_2872 | Six classes of crustaceans are generally recognized ( Table 1.1). Class Branchiopoda Characteristics Mostly small, freshwater animals that feed on plankton and detritus. Examples Brine shrimp Class Remipedia Cephalocarida Maxillopoda Ostracoda Malacostraca Characteristics A small class of blind organisms found in deep caves connected to salt water. Small crustaceans, with an eye- less head covered by a horseshoe- shaped shield; has two pairs of an- tennae and two pairs of jaws. Mostly small, with a small abdomen, and generally no appendages. Small animals with bivalve shells. The largest class, with the largest and most familiar animals. This class has the greatest diversity of body forms. Examples Nectiopoda Horseshoe shrimp Barnacles, copepods Seed shrimp Crabs, lobsters, woodlice shrimp, krill, A terrestrial arthropod, a species of woodlice. | text | null |
L_0497 | crustaceans | T_2873 | Remember that crustaceans are an arthropod subphylum, and that arthropod means "jointed feet." As expected, the majority of crustaceans can move. A few groups are parasitic and live attached to their hosts. Adult barnacles ( Figure 1.2) cannot move, so they attach themselves headfirst to a rock or log. | text | null |
L_0497 | crustaceans | T_2874 | Characteristics of crustaceans include: 1. An exoskeleton that may be bound together, such as in the carapace, the thick back shield seen in many crustaceans that often forms a protective space for the gills. 2. A main body cavity with an expanded circulatory system. Blood is pumped by a heart located near the back. 3. A digestive system consisting of a straight tube that has a gastric mill for grinding food and a pair of digestive glands that absorb food. 4. Structures that function like kidneys to remove wastes. These are located near the antennae. 5. A brain that exists in the form of ganglia, or connections between nerve cells. 6. Crustaceans periodically shed the outer skeleton, grow rapidly for a short time, and then form another hard skeleton. They cannot grow underneath their outer exoskeleton. They are very vulnerable during this time, as they lack their hard shell. | text | null |
L_0497 | crustaceans | T_2875 | Most crustaceans have separate sexes, so they reproduce sexually using eggs and sperm. Many land crustaceans, such as the Christmas Island red crab, mate every season and return to the sea to release the eggs. Others, such as woodlice, lay their eggs on land when the environment is damp. In some crustaceans, the females keep the eggs until they hatch into free-swimming larvae. | text | null |
L_0498 | cyclic behavior of animals | T_2876 | Many animal behaviors change in a regular way. They go through cycles. Some cycles of behavior repeat each year. Other cycles of behavior repeat every day. | text | null |
L_0498 | cyclic behavior of animals | T_2877 | An example of a behavior with a yearly cycle is hibernation. Hibernation is a state in which an animals body processes are slower than usual, and its body temperature falls. An animal uses less energy than usual during hibernation. This helps the animal survive during a time of year when food is scarce. Hibernation may last for weeks or months. Animals that hibernate include species of bats, squirrels, and snakes. Most people think that bears hibernate. In fact, bears do not go into true hibernation. In the winter, they go into a deep sleep. However, their body processes do not slow down very much. Their body temperature also remains about the same as usual. Bears can be awakened easily from their winter sleep. Another example of a behavior with a yearly cycle is migration. Migration is the movement of animals from one place to another. Migration is an innate behavior that is triggered by changes in the environment. For example, animals may migrate when the days get shorter in the fall. Migration is most common in birds, fish, and insects. In the Northern Hemisphere, many species of birds, including robins and geese, travel south for the winter. They migrate to areas where it is warmer and where there is more food. They return north in the spring. A flock of migrating geese is pictured below ( Figure 1.1). These geese are flying south for the win- ter. Flocks of geese migrate in V-shaped formations. Some animals migrate very long distances. The map shown below shows the migration route of a species of hawk called Swainsons hawk ( Figure 1.2). About how many miles do the hawks travel from start to finish? Are you surprised that birds migrate that far? Some species of birds migrate even farther. Whales also are known to migrate thousands of miles each year to take advantage of warmer waters in the winter months. The great migration of millions of zebra, wildebeest and other antelope in East Africa also occurs yearly. Each year around 1.5 million wildebeest and 300,000 zebra (along with other antelope) go in search of food and water, traveling a distance of around 1800 miles. Birds and other migrating animals follow the same routes each year. How do they know where to go? It depends on the species. Some animals follow landmarks, such as rivers or coastlines. Other animals are guided by the position of the sun, the usual direction of the wind, or other clues in the environment. | text | null |
L_0498 | cyclic behavior of animals | T_2878 | Many animal behaviors change at certain times of day, day after day. For example, most animals go to sleep when the sun sets and wake up when the sun rises. Animals that are active during the daytime are called diurnal. Some animals do the opposite. They sleep all day and are active during the night. These animals are called nocturnal. Examples of nocturnal animals include bats, foxes, possums, skunks and coyotes. Many mammals (including humans), insects, reptiles and birds are diurnal. Animals may eat and drink at certain times of day as well. Humans have daily cycles of behavior, too. Most people start to get sleepy after dark and have a hard time sleeping when it is light outside. Daily cycles of behavior are called circadian rhythms. In many species, including humans, circadian rhythms are controlled by a tiny structure called the biological clock. This structure is located in a gland at the base of the brain. The biological clock sends signals to the body. The signals cause regular changes in behavior and body processes. The amount of light entering the eyes helps control the biological clock. The clock causes changes that repeat every 24 hours. The migration route of Swainsons hawk starts in North America and ends in South America. Scientists learned their mi- gration route by attaching tiny tracking devices to the birds. The birds were then tracked by satellite. On the migra- tion south, the hawks travel almost 5,000 miles from start to finish. | text | null |
L_0503 | diversity of birds | T_2897 | Turkey, hummingbird, penguin, parrot, owl and eagle. These are just some of the many different types of birds. If you just think about the birds in this list, the differences are striking. About 10,000 bird species belong to 29 different orders within the class Aves. They live and breed on all seven continents. The tropics are home to the greatest biodiversity of birds. The diversity among birds is striking. Birds can vary greatly in size and color. Some fly, some swim, some just walk or run. Some are savage carnivores, others are gentle herbivores. Some are low on the food chain, others are at the top. Birds live in a variety of different habitats. Birds that live in different habitats will encounter different foods and different predators. Birds can be carnivores (feeding on other animals), herbivores (feeding on plants), or generalists (feeding on a variety of foods). The lifestyle of the bird can affect what it looks like. For example, can you think of some examples of beaks that are adapted to the type of food a bird eats? Carnivorous birds include hawks, falcons, eagles, osprey, vultures and owls. Herbivorous birds include the goose, cockatoo and parrot. The American Crow is an example of a generalist. In addition, a specialist is a bird (or other animal) that is specially adapted to eat a certain food. An example of a specialist is a hummingbird, whose long, thin beak is excellent for reaching into flowers for nectar, but not very good for eating other foods. Waterfowl are birds that live on the water. These include ducks, geese, swans, and pelicans, to name a few. Landfowl are ground-feeding birds such as chickens and turkeys. Penguins are a group of flightless birds adapted for life in the water with flippers. Diurnal raptors are birds of prey that hunt during the day. These include falcons, eagles and hawks. Nocturnal raptors hunt during the night. These include various types of owls. Parrots are brightly colored and very intelligent. They are found in the tropics and include cockatoos, parrots, and parakeets. | text | null |
L_0503 | diversity of birds | T_2898 | The size and shape of the beak is related to the food the bird eats and can vary greatly among different birds. Parrots have down-curved, hooked bills, which are well-adapted for cracking seeds and nuts ( Figure 1.1). Hummingbirds, on the other hand, have long, thin, pointed bills, which are adapted for getting the nectar out of flowers ( Figure 1.1). Hawks, eagles, falcons and owls have a sharp, hooked beak. (left) The down-curved, hooked bill of a scarlet macaw, a large colorful parrot. (right) A long, thin and pointed bill of the hummingbird. | text | null |
L_0503 | diversity of birds | T_2899 | Bird feet can also vary greatly among different birds. Some birds, such as gulls and terns and other waterfowl, have webbed feet used for swimming or floating ( Figure 1.2). Other birds, such as herons, gallinules, and rails, have four long spreading toes, which are adapted for walking delicately in the wetlands ( Figure 1.2). You can predict how the beaks and feet of birds will look depending on where they live and what type of food they eat. Flightless birds also have long legs that are adapted for running. Flightless birds include the ostrich and kiwi. Raptors have clawed feet. They also have strong legs. Hawks, eagles and falcons also have excellent vision and they hunt by sight. Owls, with excellent hearing, can hunt by that sense alone. See Wild African Vulture Birds Scavage Bones of Dead Animals at (left) The webbed feet of a great black- backed gull. (right) The long spreading toes of an American purple gallinule. Click image to the left or use the URL below. URL: | text | null |
L_0508 | ecosystems | T_2912 | Ecology is the study of ecosystems. That is, ecology is the study of how living organisms interact with each other and with the nonliving part of their environment. An ecosystem consists of all the nonliving factors and living organisms interacting in the same habitat. Recall that living organisms are biotic factors. The biotic factors of an ecosystem include all the populations in a habitat, such as all the species of plants, animals, and fungi, as well as all the micro-organisms. Also recall that the nonliving factors are called abiotic factors. Abiotic factors include temperature, water, soil, and air. You can find an ecosystem in a large body of fresh water or in a small aquarium. You can find an ecosystem in a large thriving forest or in a small piece of dead wood. Examples of ecosystems are as diverse as the rainforest, the savanna, the tundra, or the desert ( Figure 1.1). The differences in the abiotic factors, such as differences in temperature, rainfall, and soil quality, found in these areas greatly contribute to the differences seen in these ecosystems. Ecosystems can include well known sites, such as the Great Barrier Reef off the coast of Australia and the Greater Yellowstone Ecosystem of Yellowstone National Park, which actually includes a few different ecosystems, some with geothermal features, such as Old Faithful geyser. Desert Botanical Gardens in Phoenix, Ari- zona. Ecosystems need energy. Many ecosystems get their energy in the form of sunlight, which enters the ecosystem through photosynthesis. This energy then flows through the ecosystem, passed from producers to consumers. Plants are producers in many ecosystems. Energy flows from plants to the herbivores that eat the plants, and then to carnivores that eat the herbivores. The flow of energy depicts interactions of organisms within an ecosystem. Matter is also recycled in ecosystems. Biogeochemical cycles recycle nutrients, like carbon and nitrogen, so they are always available. These nutrients are used over and over again by organisms. Water is also continuously recycled. The flow of energy and the recycling of nutrients and water are examples of the interactions between organisms and the interactions between the biotic and abiotic factors of an ecosystem. | text | null |
L_0520 | fields in the life sciences | T_2934 | The life sciences are the study of living organisms. They deal with every aspect of living organisms, from the biology of cells, to the biology of individual organisms, to how these organisms interact with other organisms and their environment. The life sciences are so complex that most scientists focus on just one or two subspecialties. If you want to study insects, what would you be called? An entomologist. If you want to study the tiny things that give us the flu, then you need to enter the field of virology, the study of viruses. If you want to study the nervous system, which life science field is right for you ( Table 1.1, Table 1.2, and Table 1.3)? Field Botany Zoology Marine biology Focus Plants Animals Organisms living in oceans Field Freshwater biology Microbiology Bacteriology Virology Entomology Taxonomy Focus Organisms living in and around freshwater lakes, streams, rivers, ponds, etc. Microorganisms Bacteria Viruses Insects The classification of organisms | text | null |
L_0520 | fields in the life sciences | T_2935 | Field Cell biology Anatomy Morphology Physiology Immunology Neuroscience Developmental biology and embryology Genetics Biochemistry Molecular biology Epidemiology Evolution Focus Cells and their structures/functions Structures of animals Form and structure of living organisms Physical and chemical functions of tissues and organs Mechanisms inside organisms that protect them from disease and infection The nervous system Growth and development of plants and animals Genetic makeup of living organisms and heredity Chemistry of living organisms Nucleic acids and proteins How diseases arise and spread The changing of species over time Field Ecology Biogeography Population biology Focus How various organisms interact with their environ- ments Distribution of living organisms The biodiversity, evolution, and environmental biology of populations of organisms During the study of the life sciences, you will study cell biology, genetics, molecular biology, botany, microbi- ology, zoology, evolution, ecology, and physiology. Cell biology is the study of cellular structure and function ( Figure 1.1). Genetics is the study of heredity, which is the passing of traits (and genes) from one generation to the next. Molecular biology is the study of molecules, such as DNA and proteins. Ecologists study ecosystems, which are made of both living and nonliving parts of the environment. A botanist may work in a botanical garden, where plant life can be studied. What will you study with the other subspecialties? This illustration shows a virus among red blood cells. Which fields study red blood cells and viruses? (Keep in mind that viruses are actually much smaller than cells.) Other life science subspecialties include biogeography, which is the study of where organisms live and at what abundance. | text | null |
L_0520 | fields in the life sciences | T_2935 | Field Cell biology Anatomy Morphology Physiology Immunology Neuroscience Developmental biology and embryology Genetics Biochemistry Molecular biology Epidemiology Evolution Focus Cells and their structures/functions Structures of animals Form and structure of living organisms Physical and chemical functions of tissues and organs Mechanisms inside organisms that protect them from disease and infection The nervous system Growth and development of plants and animals Genetic makeup of living organisms and heredity Chemistry of living organisms Nucleic acids and proteins How diseases arise and spread The changing of species over time Field Ecology Biogeography Population biology Focus How various organisms interact with their environ- ments Distribution of living organisms The biodiversity, evolution, and environmental biology of populations of organisms During the study of the life sciences, you will study cell biology, genetics, molecular biology, botany, microbi- ology, zoology, evolution, ecology, and physiology. Cell biology is the study of cellular structure and function ( Figure 1.1). Genetics is the study of heredity, which is the passing of traits (and genes) from one generation to the next. Molecular biology is the study of molecules, such as DNA and proteins. Ecologists study ecosystems, which are made of both living and nonliving parts of the environment. A botanist may work in a botanical garden, where plant life can be studied. What will you study with the other subspecialties? This illustration shows a virus among red blood cells. Which fields study red blood cells and viruses? (Keep in mind that viruses are actually much smaller than cells.) Other life science subspecialties include biogeography, which is the study of where organisms live and at what abundance. | text | null |
L_0524 | food webs | T_2946 | Energy must constantly flow through an ecosystem for the system to remain stable. What exactly does this mean? Essentially, it means that organisms must eat other organisms. Food chains ( Figure 1.1) show the eating patterns in an ecosystem. Food energy flows from one organism to another. Arrows are used to show the feeding relationship between the animals. The arrow points from the organism being eaten to the organism that eats it. For example, an arrow from a plant to a grasshopper shows that the grasshopper eats the leaves. Energy and nutrients are moving from the plant to the grasshopper. Next, a bird might prey on the grasshopper, a snake may eat the bird, and then an owl might eat the snake. The food chain would be: plant grasshopper bird snake owl. A food chain cannot continue to go on and on. For example the food chain could not be: plant grasshopper spider frog lizard fox hawk. Food chains only have 4 or 5 total levels. Therefore, a chain has only 3 or 4 levels for energy transfer. This food chain includes producers and consumers. How could you add decom- posers to the food chain? In an ocean ecosystem, one possible food chain might look like this: phytoplankton krill fish shark. The producers are always at the beginning of the food chain, bringing energy into the ecosystem. Through photosynthesis, the producers create their own food in the form of glucose, but also create the food for the other organisms in the ecosystem. The herbivores come next, then the carnivores. When these consumers eat other organisms, they use the glucose in those organisms for energy. In this example, phytoplankton are eaten by krill, which are tiny, shrimp-like animals. The krill are eaten by fish, which are then eaten by sharks. Could decomposers be added to a food chain? Each organism can eat and be eaten by many different types of organisms, so simple food chains are rare in nature. There are also many different species of fish and sharks. So a food chain cannot end with a shark; it must end with a distinct species of shark. A food chain does not contain the general category of "fish," it will contain specific species of fish. In ecosystems, there are many food chains. Since feeding relationships are so complicated, we can combine food chains together to create a more accurate flow of energy within an ecosystem. A food web ( Figure 1.2) shows the feeding relationships between many organisms in an ecosystem. If you expand our original example of a food chain, you could add deer that eat clover and foxes that hunt chipmunks. A food web shows many more arrows, but still shows the flow of energy. A complete food web may show hundreds of different feeding relationships. For more information on food chains, see A Million Sharks at . | text | null |
L_0526 | frogs and toads | T_2949 | Frogs and toads are amphibians in the order Anura. In terms of classification, there is actually not a big difference between frogs and toads. Frogs often have long legs that are good for hopping, skin that is smooth and moist, and special pads on their toes that help them climb. Toads are more heavyset with shorter legs, and usually have drier skin, often with warty-looking bumps. Frogs are more likely to live in or near water than toads. Frogs are found in many areas of the world, from the tropics to subarctic regions, but most species are found in tropical rainforests. Consisting of more than 5,000 species (about 88% of amphibian species are frogs), they are among the most diverse groups of vertebrates. Frogs range in size from less than 0.5 inches in species in Brazil and Cuba to the over 1-foot (33 cm) long goliath frog of Cameroon, which can weigh up to 7 pounds. That is 1-foot from the nose to the back of the body, not including the length of the legs. Even the largest frogs are significantly smaller than common reptiles. | text | null |
L_0526 | frogs and toads | T_2950 | Adult frogs are characterized by long hind legs, a short body, webbed finger-like parts, and the lack of a tail. They also have a three-chambered heart, as do all tetrapods except birds and mammals. Most frogs live part of the time in water and part of the time on land. They move easily on land by jumping or climbing. To become great jumpers, frogs evolved long hind legs and long ankle bones. They also have a short backbone with only ten vertebrae. Frog and toad skin hangs loosely on the body, and skin texture can be smooth, warty, or folded. Frogs and toads dont have fur, feathers, or scales on their skin. Instead, they have a moist and permeable skin layer covered with mucous glands. Their special skin allows them to breathe through their skin in addition to using their lungs. They are vulnerable to water loss through the skin in dry conditions, which is why they need to live near water or in moist environments. The thin layer of mucous keeps the skin moist. In order to live on land and in water, frogs have three eyelid membranes: one is see-through to protect the eyes underwater, and the two other ones let them see on land. Frogs also have a tympanum, which acts like a simple ear. They are found on each side of the head. In some species, the tympanum is covered by skin. A tree frog. Notice the powerful muscles in the limbs and the coverings around the eyes. | text | null |
L_0526 | frogs and toads | T_2951 | Frogs typically lay their eggs in puddles, ponds, or lakes. Their larvae, or tadpoles, have gills, a tail, but no legs, and need to live in water. If fact, they are quite similar to a fish. Tadpoles develop into adult frogs in water ( Figure You may hear males "ribbiting," producing a mating call used to attract females to the bodies of water best for mating and breeding. Frog calls can occur during the day or night. Each frog species has a different call that is used to attract mates and warn off rivals. When a female picks a male whose call she likes, the male grabs her and squeezes across her back and around her abdomen. This causes the female to release her eggs. The male then fertilizes the eggs and, in some species, also guards them. | text | null |
L_0526 | frogs and toads | T_2952 | Adult frogs are meat-eaters and eat mostly insects, spiders, slugs and worms. Larger species will eat mice, birds, and even other small reptiles and amphibians. Frogs do not have teeth on their lower jaw, so they usually swallow their food whole. Some frogs have teeth on the upper jaw that are used to hold the prey in place. Frogs and toads are responsible for keeping a large part of the worlds insect population under control. They catch these insects using their long tongue. The frog tongue is about a third the length of the frogs body, though they can Frogs develop from tadpoles, which de- velop from eggs. Notice the formation of the two powerful back legs used for jumping. grow even longer. They can easily reach 12 inches long in an adult frog. Frogs tongues are attached to the front of their mouths rather than at the back like humans. They release a sticky substance at the precise moment of impact with their food. When a frog catches an insect it throws its sticky tongue out of its mouth and wraps it around its prey. The frogs tongue then snaps back and throws the food down its throat. This happens about as fast as a blink of your eyes. | text | null |
L_0527 | fungi | T_2953 | Ever notice blue-green mold growing on a loaf of bread? Do you like your pizza with mushrooms? Has a physician ever prescribed an antibiotic for you? If so, then you have encountered fungi. Fungi are organisms that belong to the Kingdom Fungi ( Figure 1.1). Our environment needs fungi. Fungi help decompose matter to release nutrients and make nutritious food for other organisms. Fungi are all around us and are useful in many ways. These many different kinds of organisms demonstrate the huge diversity within the Kingdom Fungi. | text | null |
L_0527 | fungi | T_2954 | If you had to guess, would you say a fungus is a plant or an animal? Scientists used to debate about which kingdom to place fungi in. Finally they decided that fungi were plants. But they were wrong. Now, scientists know that fungi are not plants at all. Fungi are very different from plants. The main difference between plants and fungi is how they obtain energy. Plants are autotrophs, meaning that they make their own "food" using the energy from sunlight. Fungi are heterotrophs, which means that they obtain their "food" from outside of themselves. In other words, they must "eat" their food like animals do. But they dont really eat. Instead, they absorb their nutrients. Yeasts, molds, and mushrooms are all different kinds of fungi. There may be as many as 1.5 million species of fungi ( Figure 1.2). You can easily see bread mold and mushrooms without a microscope, but most fungi you cannot see. Fungi are either too small to be seen without a microscope, or they live where you cannot see them easilydeep in the soil, under decaying logs, or inside plants or animals. Some fungi even live in, or on top of, other fungi. | text | null |
L_0527 | fungi | T_2955 | Fungi can grow fast because they are such good eaters. Fungi have lots of surface area, and this large surface area eats or absorbs. Surface area is how much exposed area an organism has, compared to their overall volume. Most of a mushrooms surface area is actually underground. If you see a mushroom in your yard, that is just a small part of a larger fungus growing underground. These are the steps involved in fungi "eating": 1. Fungi squirt special enzymes into their environment. 2. The enzymes help digest large organic molecules, similar to cutting up your food before you eat. 3. Cells of the fungi then absorb the broken-down nutrients. | text | null |
L_0528 | fungi classification | T_2956 | Scientists used to think that fungi were members of the plant kingdom. They thought this because fungi had several similarities to plants. For example: Fungi and plants have similar structures. Plants and fungi live in the same kinds of habitats, such as growing in soil. Plants and fungi cells both have a cell wall, which animals do not have. | text | null |
L_0528 | fungi classification | T_2957 | However, there are a number of characteristics that make fungi different from plants: 1. Fungi cannot make their own food like plants can, since they do not have chloroplasts and cannot carry out photosynthesis. Fungi are more like animals because they are heterotrophs, as opposed to autotrophs, like plants, that make their own food. Fungi have to obtain their food, nutrients and glucose, from outside sources. 2. The cell walls in many species of fungi contain chitin. Chitin is tough carbohydrate found in the shells of animals such as beetles and lobsters. The cell wall of a plant is made of cellulose, not chitin. 3. Unlike many plants, most fungi do not have structures, such as xylem and phloem, that transfer water and nutrients. | text | null |
L_0528 | fungi classification | T_2958 | The Kingdom Fungi can be broken down into several phyla. Each phyla has some unique traits. And even within the same phyla there are many differences among the fungi. Various types of fungi are pictured below ( Table 1.1). Notice how different each of these organisms are from one another. Type of Fungi Molds Examples Penicillium Mushrooms Morels, shiitake, cremini, oyster Single-celled yeasts Bakers yeast | text | null |
L_0529 | fungi reproduction | T_2959 | Different fungi reproduce in different ways. Many fungi reproduce both sexually and asexually. However, some reproduce only sexually and some only asexually. Asexual reproduction involves just one parent and sexual repro- duction involves two parents. | text | null |
L_0529 | fungi reproduction | T_2960 | Through asexual reproduction, new organisms are produced that are genetically identical to the parent. That is, they have exactly the same DNA. Fungi reproduce asexually through three methods: 1. Spores: Spores are formed by the fungi and released to create new fungi. This is the powdery substance released by puffballs. Spores are haploid reproductive cells found in some bacteria, plants, algae, fungi, and protozoa. Theoretically, spores can reproduce asexually to produce countless offspring. Obviously this does not happen. If it did, the world would be covered by genetically identical fungi. 2. Budding: The fungus grows a new part of its body, which eventually breaks off. The broken-off piece becomes a new organism ( Figure 1.1). 3. Fragmentation: In this method, a piece of the mycelium, the body of the fungus, splits off. The resulting fragment can eventually produce a new colony of fungi. Asexual reproduction is faster and produces more fungi than sexual reproduction. This form of reproduction is controlled by many different factors. Outside conditions, such as the availability of food, determine when a fungus undergoes asexual reproduction. | text | null |
L_0529 | fungi reproduction | T_2961 | Almost all fungi can reproduce sexually. But why reproduce sexually when asexual reproduction is much quicker? Sexual reproduction brings together traits from the two parents. This increases the genetic diversity of the species. In plants and animals, sexual reproduction occurs when sperm and egg from two parents join to make a new individual. In fungi, however, two haploid hyphae meet together and their nuclei fuse. Instead of calling a hyphae male or female, they have different mating types, such as (+) and (-) ( Figure 1.2). The common mushroom, a fruiting body, results after sexual reproduction when two hyphae, one (+) and one (-), mate, forming a mycelium with sporangia. No- tice, when the sporangia burst, the spores are released from the fruiting body. | text | null |
L_0534 | gymnosperms | T_2971 | Gymnosperms have seeds, but they do not produce fruit. Instead, the seeds of gymnosperms are usually found in cones. There are four phyla of gymnosperms: 1. Conifers 2. Cycads 3. Ginkgoes 4. Gnetophytes | text | null |
L_0534 | gymnosperms | T_2972 | Conifers, members of the phylum Coniferophyta, are probably the gymnosperms that are most familiar to you. Conifers include trees such as pines, firs, spruces, cedars, and the coastal redwood trees in California, which are the tallest living vascular plants. Conifers have their reproductive structures in cones, but they are not the only plants to have that trait ( Figure 1.1). Conifer pollen cones are usually very small, while the seed cones are larger. Pollen contains gametophytes that produce the male gamete of seed plants. The pollen, which is a powder-like substance, is carried by the wind to fertilize the seed cones that contain the female gamete ( Figure 1.2). Conifers have many uses. They are important sources of lumber and are also used to make paper. Resins, the sticky substance you might see oozing out of a wound on a pine tree, are collected from conifers to make a variety of products, such as the solvent turpentine and the rosin used by musicians and baseball players. The sticky rosin improves the pitchers hold on the ball or increases the friction between the bow and the strings to help create music from a violin or other stringed instrument. | text | null |
L_0534 | gymnosperms | T_2973 | Cycads, in the phylum Cycadophyta, are also gymnosperms. They have large, finely-divided leaves and grow as short shrubs and trees in tropical regions. Like conifers, they produce cones, but the seed cones and pollen cones are always on separate plants ( Figure 1.3). One type of cycad, the Sago Palm, is a popular landscape plant. During the Age of the Dinosaurs (about 65 to 200 million years ago), cycads were the dominant plants. So you can imagine dinosaurs grazing on cycad seeds and roaming through cycad forests. The end of a pine tree branch bears the male cones that produce the pollen. Cycads bear their pollen and seeds in cones on separate plants. | text | null |
L_0534 | gymnosperms | T_2973 | Cycads, in the phylum Cycadophyta, are also gymnosperms. They have large, finely-divided leaves and grow as short shrubs and trees in tropical regions. Like conifers, they produce cones, but the seed cones and pollen cones are always on separate plants ( Figure 1.3). One type of cycad, the Sago Palm, is a popular landscape plant. During the Age of the Dinosaurs (about 65 to 200 million years ago), cycads were the dominant plants. So you can imagine dinosaurs grazing on cycad seeds and roaming through cycad forests. The end of a pine tree branch bears the male cones that produce the pollen. Cycads bear their pollen and seeds in cones on separate plants. | text | null |
L_0534 | gymnosperms | T_2974 | Ginkgoes, in the phylum Ginkgophyta, are unique because they are the only species left in the phylum. Many other species in the fossil record have gone extinct ( Figure 1.4). The ginkgo tree is sometimes called a "living fossil" because it is the last species from its phylum. One reason the ginkgo tree may have survived is because it was often grown around Buddhist temples, especially in China. The ginkgo tree is also a popular landscape tree today in American cities because it can live in polluted areas better than most plants. Ginkgoes, like cycads, has separate female and male plants. The male trees are usually preferred for landscaping because the seeds produced by the female plants smell terrible when they ripen. Ginkgo trees are gymnosperms with broad leaves. | text | null |
L_0534 | gymnosperms | T_2975 | Gnetophytes, in the phylum Gnetophyta, are a very small and unusual group of plants. Ephedra is an important member of this group, since this desert shrub produces the ephedrine used to treat asthma and other conditions. Welwitschia produces extremely long leaves and is found in the deserts of southwestern Africa ( Figure 1.5). Overall, there are about 70 different species in this diverse phylum. One type of gnetophyte is Welwitschia. | text | null |
L_0535 | habitat and niche | T_2977 | Each organism plays a particular role in its ecosystem. A niche is the role a species plays in the ecosystem. In other words, a niche is how an organism makes a living. A niche will include the organisms role in the flow of energy through the ecosystem. This involves how the organism gets its energy, which usually has to do with what an organism eats, and how the organism passes that energy through the ecosystem, which has to do with what eats the organism. An organisms niche also includes how the organism interacts with other organisms, and its role in recycling nutrients. Once a niche is left vacant, other organisms can fill that position. For example when the Tarpan, a small wild horse found mainly in southern Russia, became extinct in the early 1900s, its niche was filled by a small horse breed, the Konik ( Figure 1.1). Often this occurs as a new species evolves to occupy the vacant niche. A species niche must be specific to that species; no two species can fill the same niche. They can have very similar niches, which can overlap, but there must be distinct differences between any two niches. If two species do fill the same niche, they will compete for all necessary resources. One species will out compete the other, forcing the other species to adapt or risk extinction. This is known as competitive exclusion. When plants and animals are introduced, either intentionally or by accident, into a new environment, they can occupy the existing niches of native organisms. Sometimes new species out-compete native species, and the native species may go extinct. They can then become a serious pest. For example, kudzu, a Japanese vine, was planted in the southeastern United States in the 1870s to help control soil loss. Kudzu had no natural predators, so it was able to out-compete native species of vine and take over their niches ( Figure 1.2). | text | null |
L_0535 | habitat and niche | T_2978 | The habitat is the physical area where a species lives. Many factors are used to describe a habitat. The average amount of sunlight received each day, the range of annual temperatures, and average yearly rainfall can all describe a habitat. These and other abiotic factors will affect the kind of traits an organism must have in order to survive there. The temperature, the amount of rainfall, the type of soil and other abiotic factors all have a significant role in determining the plants that invade an area. The plants then determine the animals that come to eat the plants, and so on. A habitat should not be confused with an ecosystem: the habitat is the actual place of the ecosystem, whereas the ecosystem includes both the biotic and abiotic factors in the habitat. Habitat destruction means what it sounds likean organisms habitat is destroyed. Habitat destruction can cause a population to decrease. If bad enough, it can also cause species to go extinct. Clearing large areas of land for housing developments or businesses can cause habitat destruction. Poor fire management, pest and weed invasion, and storm damage can also destroy habitats. National parks, nature reserves, and other protected areas all preserve habitats. Santa Cruz Island off the California coast has diverse habitats including a coastline with steep cliffs, coves, gigantic caves, and sandy beaches. | text | null |
L_0535 | habitat and niche | T_2978 | The habitat is the physical area where a species lives. Many factors are used to describe a habitat. The average amount of sunlight received each day, the range of annual temperatures, and average yearly rainfall can all describe a habitat. These and other abiotic factors will affect the kind of traits an organism must have in order to survive there. The temperature, the amount of rainfall, the type of soil and other abiotic factors all have a significant role in determining the plants that invade an area. The plants then determine the animals that come to eat the plants, and so on. A habitat should not be confused with an ecosystem: the habitat is the actual place of the ecosystem, whereas the ecosystem includes both the biotic and abiotic factors in the habitat. Habitat destruction means what it sounds likean organisms habitat is destroyed. Habitat destruction can cause a population to decrease. If bad enough, it can also cause species to go extinct. Clearing large areas of land for housing developments or businesses can cause habitat destruction. Poor fire management, pest and weed invasion, and storm damage can also destroy habitats. National parks, nature reserves, and other protected areas all preserve habitats. Santa Cruz Island off the California coast has diverse habitats including a coastline with steep cliffs, coves, gigantic caves, and sandy beaches. | text | null |
L_0536 | habitat destruction | T_2979 | From a human point of view, a habitat is where you live, go to school, and go to have fun. Your habitat can be altered, and you can easily adapt. Most people live in a few different places and go to a number of different schools throughout their life. But a plant or animal may not be able to adapt to a changed habitat. A habitat is the natural home or environment of an organism. Humans often destroy the habitats of other organisms. Habitat destruction can cause the extinction of species. Extinction is the complete disappearance of a species. Once a species is extinct, it can never recover. Some ways humans cause habitat destruction are by clearing land and by introducing non-native species of plants and animals. | text | null |
L_0536 | habitat destruction | T_2980 | Clearing land for agriculture and development is a major cause of habitat destruction. Within the past 100 years, the amount of total land used for agriculture has almost doubled. Land used for grazing cattle has more than doubled. Agriculture alone has cost the United States half of its wetlands ( Figure 1.1) and almost all of its tallgrass prairies. Native prairie ecosystems, with their thick fertile soils, deep-rooted grasses, diversity of colorful flowers, burrowing prairie dogs, and herds of bison and other animals, have virtually disappeared ( Figure 1.3). Wetlands such as this one in Cape May, New Jersey, filter water and protect coastal lands from storms and floods. The Flint Hills contain some of the largest remnants of tallgrass prairie habitat remaining in North America. | text | null |
L_0536 | habitat destruction | T_2980 | Clearing land for agriculture and development is a major cause of habitat destruction. Within the past 100 years, the amount of total land used for agriculture has almost doubled. Land used for grazing cattle has more than doubled. Agriculture alone has cost the United States half of its wetlands ( Figure 1.1) and almost all of its tallgrass prairies. Native prairie ecosystems, with their thick fertile soils, deep-rooted grasses, diversity of colorful flowers, burrowing prairie dogs, and herds of bison and other animals, have virtually disappeared ( Figure 1.3). Wetlands such as this one in Cape May, New Jersey, filter water and protect coastal lands from storms and floods. The Flint Hills contain some of the largest remnants of tallgrass prairie habitat remaining in North America. | text | null |
L_0536 | habitat destruction | T_2981 | Other habitats that are being rapidly destroyed are forests, especially tropical rainforests. The largest cause of deforestation today is slash-and-burn agriculture (shown in the opening image). This means that when people want to turn a forest into a farm, they cut down all of the trees and then burn the remainder of the forest. This technique is used by over 200 million people in tropical forests throughout the world. As a consequence of slash-and-burn agriculture, nutrients are quickly lost from the soil. This often results in people abandoning the land within a few years. Then the top soil erodes and desertification can follow. Desertification Herds of bison also made up part of the tallgrass prairie community. turns forest into a desert, where it is difficult for plants to grow. Half of the Earths mature tropical forests are gone. At current rates of deforestation, all tropical forests will be gone by the year 2090. | text | null |
L_0536 | habitat destruction | T_2982 | One of the main causes of extinction is introduction of exotic species into an environment. These exotic and new species can also be called invasive species or non-native species. These non-native species, being new to an area, may not have natural predators in the new habitat, which allows their populations to easily adapt and grow. Invasive species out-compete the native species for resources. Sometimes invasive species are so successful at living in a certain habitat that the native species go extinct ( Figure 1.4). Recently, cargo ships have transported zebra mussels, spiny waterfleas, and ruffe (a freshwater fish) into the Great Lakes ( Figure 1.5). These invasive species are better at hunting for food. They have caused some of the native species to go extinct. Invasive species can disrupt food chains, carry disease, prey on native species directly, and out-compete native species for limited resources, like food. All of these effects can lead to extinction of the native species. | text | null |
L_0536 | habitat destruction | T_2983 | Other causes of habitat destruction include poor fire management, overfishing, mining ( Figure 1.6), pollution, and storm damage. All of these can cause irreversible changes to a habitat and ecosystem. | text | null |
L_0536 | habitat destruction | T_2984 | A habitat that is quickly being destroyed is the wetland. By the 1980s, over 80% of all wetlands in parts of the U.S. were destroyed. In Europe, many wetland species have gone extinct. For example, many bogs in Scotland have been lost because of human development. Another example of species loss due to habitat destruction happened on Madagascars central highland plateau. From 1970 to 2000, slash-and-burn agriculture destroyed about 10% of the countrys total native plants. The area turned into a wasteland. Soil from erosion entered the waterways. Much of the river ecosystems of several large rivers were also destroyed. Several fish species are almost extinct. Also, some coral reef formations in the Indian Ocean are completely lost. | text | null |
L_0536 | habitat destruction | T_2984 | A habitat that is quickly being destroyed is the wetland. By the 1980s, over 80% of all wetlands in parts of the U.S. were destroyed. In Europe, many wetland species have gone extinct. For example, many bogs in Scotland have been lost because of human development. Another example of species loss due to habitat destruction happened on Madagascars central highland plateau. From 1970 to 2000, slash-and-burn agriculture destroyed about 10% of the countrys total native plants. The area turned into a wasteland. Soil from erosion entered the waterways. Much of the river ecosystems of several large rivers were also destroyed. Several fish species are almost extinct. Also, some coral reef formations in the Indian Ocean are completely lost. | text | null |
L_0554 | human uses of fungi | T_3036 | Fungi are extremely important to the ecosystem because they are one of the major decomposers of organic material. Decomposing organic material is how fungi acquire energy. But fungi have other roles in addition to being decom- posers. How do fungi help people? They are used to help prepare food and beverages, and they have many other uses. | text | null |
L_0554 | human uses of fungi | T_3037 | Yeasts are crucial for the fermentation process that makes beer, wine, and bread. Fermentation occurs in the absence of oxygen and allows the first step of cellular respiration, glycolysis, to continue. Some fungi are used in the production of soy sauce and tempeh, a source of protein used in Southeast Asia. Fungi can produce antibiotics, such as penicillin. Antibiotics are important medicines that kill bacteria, and penicillin was the first identified cure against many deadly bacterial species. Antibiotics only treat bacterial diseases; they can not be used to treat viral or fungal diseases. Mushrooms are fungi that are eaten by people all over the globe. The video Bread Mold Kills Bacteria at explains Alexander Flemings famous discovery that lead to the discovery of the antibiotic penicillin. Antibiotics are used to kill Saccharomyces cerevisiae, a single-celled fungus called brewers or bakers yeast, is used in the baking of bread and in making wine and beer through fermentation. harmful bacteria. See Alexander Fleming 1881 - 1955 at Click image to the left or use the URL below. URL: | text | null |
L_0554 | human uses of fungi | T_3038 | Some of the best known types of fungi are mushrooms, which can be edible or poisonous ( Figure 1.2). Many species are grown commercially, but others are harvested from the wild. When you order a pizza with mushrooms or add them to your salad, you are most likely eating Agaricus bisporus, known as white or button mushrooms, the most commonly eaten species. Other mushroom species are gathered from the wild for people to eat or for commercial sale. Many mushroom species are poisonous to humans. Some mushrooms will simply give you a stomachache, while others may kill you. Some mushrooms you can eat when they are cooked but are poisonous when raw. So if you find mushrooms in the wild, dont eat them until you are certain they are safe! Have you ever eaten blue cheese? Do you know what makes it blue? You guessed it. A fungus. For certain types of cheeses, producers add fungal spores to milk curds to promote the growth of mold, which makes the cheese blue. Molds used in cheese production are safe for humans to eat. Some fungi are poisonous and must be avoided. | text | null |
L_0555 | human vision | T_3039 | Think about all the ways that students use their sense of sight during a typical school day. As soon as they open their eyes in the morning, they might look at the clock to see what time it is. Then, they might look out the window to see what the weather is like. They probably look in a mirror to comb their hair. In school, they use their eyes to read the board, their textbooks, and the expressions on their friends faces. After school, they might keep their eye on the ball while playing basketball ( Figure 1.1). Then, they might read their homework assignment and text messages from their friends. Sight, or vision, is the ability to see light. It depends on the eyes detecting light and forming images. It also depends on the brain making sense of the images, so that we know what we are seeing. Human beings and other primates depend on vision more than many other animals. Its not surprising, then, that we have a better sense of vision than many other animals. Not only can we normally see both distant and close-up objects clearly, but we can also see in three dimensions and in color. But humans do not have the best vision. You may think you see things fairly clearly. Imagine if you could see even better. How about 8 times better? Raptors, or birds of prey, including the eagles, hawks and falcons can see up to 8 times more clearly than the sharpest human eye. A golden eagle for example can see a rabbit from a mile away. Why do you think they have such a good sense of vision? Other animals also have much better night vision then us. | text | null |
L_0555 | human vision | T_3040 | Did you ever use 3-D glasses to watch a movie, like the boy pictured below ( Figure 1.2)? If you did, then you know that the glasses make people and objects in the movie appear to jump out of the screen. They make images on the flat movie screen seem more realistic because they give them depth. Thats the difference between seeing things in two dimensions and three dimensions. We are able to see in three dimensions because we have two eyes facing the same direction but a few inches apart. As a result, we see objects and people with both eyes at the same time but from slightly different angles. Hold up a finger a few inches away from your face, and look at it, first with one eye and then with the other. Youll notice that your finger appears to move. Now hold up your finger at arms length, and look at it with one eye and then the other. Your finger seems to move less than it did when it was closer. Although you arent aware of it, your brain constantly uses such differences to determine the distance of objects. | text | null |
L_0555 | human vision | T_3041 | For animals like us that see in color, it may be hard to imagine a world that appears to be mainly shades of gray. You can get an idea of how many other animals see the world by looking at a black-and-white picture of colorful objects. For example, look at the apple on the tree pictured below ( Figure 1.3). In the top picture, they appear in color, the way you would normally see them. In the bottom picture they appear without color, in shades of gray ( Figure 1.4). Humans with color vision see the apple on this tree; the bright red color of the apple stands out clearly from the green background of leaves. This black-and-white picture gives an idea of how many animals see the world. Dogs and cats would see the green and red colors as shades of gray; they are able to see blue, but red and green appear the same to them. Many animals see just one or two colors. Some see colors that we cannot see. Apes and chimps see the same colors as us. But whereas many animals cannot see colors, some animals see colors that we cannot. The range of color vision of bees and butterflies for example, extends beyond the visible spectrum of light we can see. The leaves of the flowers they pollinate have special ultraviolet patterns which guide the insects deep into the flower. | text | null |
L_0555 | human vision | T_3041 | For animals like us that see in color, it may be hard to imagine a world that appears to be mainly shades of gray. You can get an idea of how many other animals see the world by looking at a black-and-white picture of colorful objects. For example, look at the apple on the tree pictured below ( Figure 1.3). In the top picture, they appear in color, the way you would normally see them. In the bottom picture they appear without color, in shades of gray ( Figure 1.4). Humans with color vision see the apple on this tree; the bright red color of the apple stands out clearly from the green background of leaves. This black-and-white picture gives an idea of how many animals see the world. Dogs and cats would see the green and red colors as shades of gray; they are able to see blue, but red and green appear the same to them. Many animals see just one or two colors. Some see colors that we cannot see. Apes and chimps see the same colors as us. But whereas many animals cannot see colors, some animals see colors that we cannot. The range of color vision of bees and butterflies for example, extends beyond the visible spectrum of light we can see. The leaves of the flowers they pollinate have special ultraviolet patterns which guide the insects deep into the flower. | text | null |
L_0555 | human vision | T_3042 | Why do you think primates, including humans, evolved the ability to see in three dimensions and in color? To answer that question, you need to know a little about primate evolution. Millions of years ago, primate ancestors lived in trees. To move about in the trees, they needed to be able to judge how far away the next branch was. Otherwise, they might have a dangerous fall. Being able see in depth was important. It was an adaptation that would help tree-living primates survive. Primate ancestors also mainly ate fruit. They needed to be able to spot colored fruits in the leafy background of the trees ( Figure 1.5). They also had to be able to judge which fruits were ripe and which were still green. Ripe fruits are usually red, orange, yellow, or purple. Being able to see in color was important for finding food. It was an adaptation that would help fruit-eating primates survive. | text | null |
L_0556 | humans and primates | T_3043 | The great apes are the members of the biological family Hominidae, which includes four living genera: chimpanzees, gorillas, orangutans and humans. Among these four genera are just seven species, two of each except humans, which has only one species, Homo sapiens. | text | null |
L_0556 | humans and primates | T_3044 | The Great Apes are large, tailless primates, ranging in size from the pygmy chimpanzee, at 66-88 pounds in weight, to the gorilla, at 300-400 pounds ( Figure 1.1). In all species, the males are, on average, larger and stronger than the females. A Western Lowland gorilla, member of the great apes. The gorilla is the largest of the hominids, weighing up to 309-397 lbs. Most living primate species are four-footed, but all are able to use their hands for gathering food or nesting materials. In some cases, hands are used as tools, such as when gorillas use sticks to measure the depth of water ( Figure 1.2). Chimpanzees sharpen sticks to use as spears in hunting; they also use sticks to gather food and to fish for termites. Most primate species eat both plants and meat ( omnivorous), but fruit is the preferred food among all but humans. In contrast, humans eat a large amount of highly processed, low fiber foods, and unusual proportions of grains and vertebrate meat. As a result of our diets, human teeth and jaws are markedly smaller for our size than those of other apes. Humans may have been eating cooked food for a million years or more, so perhaps our teeth adapted to eating cooked food. Gorillas and chimpanzees live in family groups of approximately five to ten individuals, although larger groups are sometimes observed. The groups include at least one dominant male, and females leave the group when they can mate. Orangutans, however, generally live alone. | text | null |
L_0556 | humans and primates | T_3044 | The Great Apes are large, tailless primates, ranging in size from the pygmy chimpanzee, at 66-88 pounds in weight, to the gorilla, at 300-400 pounds ( Figure 1.1). In all species, the males are, on average, larger and stronger than the females. A Western Lowland gorilla, member of the great apes. The gorilla is the largest of the hominids, weighing up to 309-397 lbs. Most living primate species are four-footed, but all are able to use their hands for gathering food or nesting materials. In some cases, hands are used as tools, such as when gorillas use sticks to measure the depth of water ( Figure 1.2). Chimpanzees sharpen sticks to use as spears in hunting; they also use sticks to gather food and to fish for termites. Most primate species eat both plants and meat ( omnivorous), but fruit is the preferred food among all but humans. In contrast, humans eat a large amount of highly processed, low fiber foods, and unusual proportions of grains and vertebrate meat. As a result of our diets, human teeth and jaws are markedly smaller for our size than those of other apes. Humans may have been eating cooked food for a million years or more, so perhaps our teeth adapted to eating cooked food. Gorillas and chimpanzees live in family groups of approximately five to ten individuals, although larger groups are sometimes observed. The groups include at least one dominant male, and females leave the group when they can mate. Orangutans, however, generally live alone. | text | null |
L_0556 | humans and primates | T_3045 | Gorillas, chimpanzees, and humans have more than 97% of their DNA sequence in common. This means that a similar percent of the amino acid sequences of the proteins will be the same, resulting in many proteins with similar or identical functions. All organisms in the Hominidae communicate with some kind of language. They can also create simple cultures beyond the family or group of animals. Having a culture means that knowledge and behaviors can be passed on from generation to generation. | text | null |
L_0556 | humans and primates | T_3046 | Specialized features of Homo sapiens include the following: small front teeth (canines and incisors) and very large molars relative to other primate species, a fully upright posture resulting in bipedalism (walking on two limbs instead of four), shortening of the arms relative to the legs, increased usefulness (dexterity) of the hands, increase in brain size, especially in the frontal lobes and a decrease in bone mass of the skull and face. See Communication - the Jane Goodall Institute at , Com- paring the Human and Chimpanzee Genomes at http://wrl.it/show/197403/12898478 , and Discovering Gibbons at Click image to the left or use the URL below. URL: | text | null |
L_0558 | importance of arthropods | T_3048 | Have you ever been startled by a bee landing on a flower? Or surprised by a swarm of pill bugs when you overturned a rock? These arthropods might seem a little scary to you, but they are actually performing important roles in the environment. Arthropods are important to the ecosystem and to humans in many ways. | text | null |
L_0558 | importance of arthropods | T_3049 | Many species of crustaceans, especially crabs, lobsters ( Figure 1.1), shrimp, prawns, and crayfish, are consumed by humans, and are now farmed on a large commercial scale. Nearly 10,000,000 tons of arthropods as food were produced in 2005. Over 70% by weight of all crustaceans caught for consumption are shrimp and prawns. Over 80% is produced in Asia, with China producing nearly half the worlds total. Insects and their grubs are at least as nutritious as meat, and are eaten both raw and cooked in many cultures. Beetles, locusts, butterflies, ants, and stinkbugs (which have an apple flavor) are insects that are regularly eaten by people in dozens of countries. In fact, there are more than 1,900 edible insect species on Earth, hundreds of which are already part of the diet of about two billion people worldwide. This is just under one of every three people worldwide, and this number should continue to grow in the future. The intentional cultivation of arthropods and other small animals for human food, referred to as minilivestock, is now emerging in animal husbandry as an ecologically sound concept. However, the greatest contribution of arthropods to human food supply is by pollination. Three-fourths of the worlds flowering plants and about 35% of the worlds food crops depend on animal pollinators to reproduce and increase crop yields. More than 3,500 species of native bees pollinate crops. Some scientists estimate that one out of every three bites of food we eat exists because of animal pollinators, including birds and bats and arthropods like bees, butterflies and moths, and beetles and other insects. Lobsters are one kind of arthropod food source. | text | null |
L_0558 | importance of arthropods | T_3050 | Humans use mites to prey on unwanted arthropods on farms or in homes. Other arthropods are used to control weed growth. Populations of whip scorpions added to an environment can limit the populations of cockroaches and crickets. Millipedes also control the harmful growth of destructive fungi and bacteria. When the numbers of millipedes is low, the imbalance between predator and prey can cause harmful microorganisms to flourish, and it can became difficult to manage plagues and diseases through natural processes. Cockroaches, spiders, mites, ticks and all other insects considered as carnivorous, prey on smaller species to maintain ecological balance. Thus, communities that have a good balance of these arthropods tend to have better pest control. | text | null |
L_0558 | importance of arthropods | T_3051 | Many arthropods have extremely important roles in ecosystems. Arthropods are of ecological importance because of their sheer numbers and extreme diversity. As mentioned above, bees, wasps, ants, butterflies, moths, flies and beetles are invaluable agents of pollination. Pollens and grains became accidentally attached to their chests and legs and are transferred to other agricultural crops as these animals move about, either by walking or flying. Most plants actually produce scents to send signals to insects that food (in the form of nectar) is available. Mites, ticks, centipedes, and millipedes are decomposers, meaning they break down dead plants and animals and turn them into soil nutrients. This is an important role because it supplies the plants with the minerals and nutrients necessary for life. It also keeps dead material from accumulating in the environment. Plants then pass along those minerals and nutrients to the animals that eat the plants. | text | null |
L_0558 | importance of arthropods | T_3052 | Arthropods are also invaluable to humans, as they are used in many different human-made products. Examples are: Bees produce honey and their honeycombs contain beeswax, widely used for making candles, furniture wax and polishes, waxed papers, antiseptics, and fillings for surgical uses. The pollens stored in honeycombs were discovered to have a rich mixture of vitamins, enzymes, and amino acids that could provide medical benefits. They were used as ingredients for supplements and medications that could provide relief for colds, asthma, and hay fever. Silk produced by arthropods, like those produced by caterpillars to protect their cocoons, is strong enough to use and be woven into fabrics, a discovery first used in ancient Chinas silk industry. The spiders web was discovered as an additional material that could provide strength, and has became essential raw materials for Kevlar vests, fishing nets, surgical sutures, and adhesives, as they contained natural antiseptics. | text | null |
L_0559 | importance of biodiversity | T_3053 | Biodiversity is a measurement of the amount of variation of the species in a given area. More specifically, biodi- versity can be defined as the variety of life and its processes, including the variety of living organisms, the genetic differences among them, and the communities and ecosystems in which they occur. A place such as a coral reef has many different species of plants and animals. That means the coral reef is a ecosystem with high biodiversity ( Figure 1.1). Because of its biodiversity, the rainforest shown above is an ecosystem with extreme importance. Why is biodiversity so important? In addition to maintaining the health and stability of the ecosystem, the diversity of life provides us with many benefits. Extinction is a threat to biodiversity. Does it matter if we are losing thousands of species each year? The answer is yes. It matters even if we consider not only the direct benefits to humans, but also the benefits to the ecosystems. The health and survival of ecosystems is related to that ecosystems biodiversity. Coral reefs are one of the biomes with the highest biodiversity on Earth. | text | null |
L_0559 | importance of biodiversity | T_3054 | Economically, there are many direct benefits of biodiversity. As many as 40,000 species of fungi, plants, and animals provide us with many varied types of clothing, shelter, medicines and other products. These include poisons, timber, fibers, fragrances, papers, silks, dyes, adhesives, rubber, resins, skins, furs, and more. According to one survey, 57% of the most important prescription drugs come from nature. Specifically, they come from bacteria, fungi, plants, and animals ( Figure 1.2). But only a small amount of species with the ability to give us medicines have been explored. The loss of any species may mean the loss of new medicines, which will have a direct effect on human health. Aspirin originally came from the bark of the white willow tree, pictured here. | text | null |
L_0559 | importance of biodiversity | T_3055 | Nature has inspired many technologies in use today. Bionics, also known as biomimetics or biomimicry, uses organisms to inspire technology or engineering projects. By studying animals and their traits, we are able to gain valuable information that we can put to use to help us. For example, rattlesnake heat-sensing pits helped inspire the development of infrared sensors. Zimbabwes Eastgate Centre ( Figure 1.3) was inspired by the air-conditioning efficiency of a termite mound ( Figure 1.4). Design of the Eastgate Centre (brown building), in Zimbabwe, which requires just 10% of the energy needed for a con- ventional building of the same size, was inspired by a biological design. | text | null |
L_0559 | importance of biodiversity | T_3056 | Biodiversity also has many benefits to ecosystems. High biodiversity makes ecosystems more stable. What can happen to an ecosystem if just one species goes extinct? What if that one species was a producer or decomposer? Would the loss of a producer have an effect on all the organisms that relied on that producer? If a decomposer vanishes, are there other decomposers to fill the void? Maybe the resulting species will adapt. Other species may fill in the niche left by the extinct species. But the extinction of one species could have a "domino" effect, resulting in the extinction of other species. This could greatly effect the stability of the whole ecosystem. The air-conditioning efficiency of this ter- mite mound was the inspiration for the Eastgate Centre. One important role of biodiversity is that it helps keep the nutrients, such as nitrogen, in the soil. For example, a diversity of organisms in the soil allows nitrogen fixation and nutrient recycling to happen. Biodiversity also allows plants to be pollinated by different types of insects. And of course, different species of fungi are necessary to recycle wastes from dead plants and animals. These are just a few of the many examples of how biodiversity is important for ecosystems. | text | null |
L_0560 | importance of birds | T_3057 | You are probably familiar with birds as food. People have always hunted birds for food. People eventually discovered that certain wild fowl (ducks, chickens, turkeys) could be tamed. This discovery led to the development of poultry, which is domesticated fowl that farmers raise for meat and eggs. Chickens are probably the oldest kinds of poultry. Chickens were domesticated in Asia at least 3,000 years ago. Since then, farmers have developed other poultry, including ducks, geese, guineafowl, pheasants, and turkeys. Around the world, people consume all these birds, and even more exotic birds, like ostriches. Today, chickens rank as the most widely raised poultry by far. Farmers throughout the world produce hundreds of millions of chickens annually for meat and eggs. Ducks and turkeys rank second and third in production worldwide. Ducks are raised for both meat and eggs. Turkeys are raised mainly for meat. Can you think of other ways that birds are important? | text | null |
L_0560 | importance of birds | T_3058 | 1. In agriculture, humans harvest bird droppings for use as fertilizer. These droppings have a high content of nitrogen, phosphate, and potassium, three nutrients essential for plant growth. 2. Chickens are also used as an early warning system of human diseases, such as West Nile virus. Mosquitoes carry the West Nile virus, bite young chickens and other birds, and infect them with the virus. When chickens or other birds become infected, humans may also become infected in the near future. 3. Birds have important cultural relationships with humans. Birds are common pets in the Western world. Common bird pets include canaries, parrots, finches, and parakeets. Sometimes, people act cooperatively with birds. For example, the Borana people in Africa use birds to guide them to honey that they use in food. 4. Birds also play prominent and diverse roles in folklore, religion, and popular culture. They have been featured in art since prehistoric times, when they appeared in early cave paintings. Many young child know of Big Bird, a very large canary of Sesame Street fame. 5. Feathers are also used all over the world to stuff pillows, mattresses, sleeping bags, coats, and quilting. Goose feathers are preferred because they are soft. Manufacturers often mix goose feathers with down feathers to provide extra softness. | text | null |
L_0560 | importance of birds | T_3059 | Birds are obviously important members of many ecosystems. They are integral parts of food chains and food webs. In a woodland ecosystem for example, some birds get their food mainly from plants. Others chiefly eat small animals, such as insects or earthworms. Birds and bird eggs, in turn, serve as food for such animals as foxes, raccoons, and snakes. The feeding relationships among all the animals in an ecosystem help prevent any one species from becoming too numerous. Birds play a vital role in keeping this balance of nature. In addition to being important parts of food webs, birds play other roles within ecosystems. 1. Birds eat insects. They are a natural way to control pests in gardens, on farms, and other places. A group of birds gliding through the air can easily eat hundreds of insects each day. Insect eating birds include warblers, bluebirds and woodpeckers. 2. Nectar-feeding birds are important pollinators, meaning they move the pollen from flower to flower to help fertilize the sex cells and create new plants. Hummingbirds, sunbirds, and the honey-eaters are common pollinators. 3. Many fruit-eating birds help disperse seeds. After eating fruit, they carry the seeds in their intestines and deposit them in new places. Fruit-eating birds include mockingbirds, orioles, finches and robins. 4. Birds are often important to island ecology. In New Zealand, the kereru and kokako are important browsers, or animals that eat or nibble on leaves, tender young shoots, or other vegetation ( Figure 1.1). Seabirds add nutrients to soil and to water with their production of guano, their dung. The kereru (left) and the kokako (right) are important browser species in New Zealand | text | null |
L_0561 | importance of echinoderms | T_3060 | Echinoderms are important for the ecosystem. They are also a source of food and medicine for humans. | text | null |
L_0561 | importance of echinoderms | T_3061 | Echinoderms play numerous ecological roles. Sand dollars and sea cucumbers burrow into the sand, providing more oxygen at greater depths of the sea floor. This allows more organisms to live there. In addition, starfish prevent the growth of algae on coral reefs. This allows the coral to filter-feed more easily. And many sea cucumbers provide a habitat for parasites such as crabs, worms, and snails. Echinoderms are also an important step in the ocean food chain. Echinoderms are the staple diet of many animals, including the sea otter. On the other hand, echinoderms eat seaweed and keep its growth in check. Recall that the sea urchin is a grazer, mainly feeding on algae on the coral and rocks. Recently, some marine ecosystems have been overrun by seaweed. Excess seaweed can destroy entire reefs. Scientists believe that the extinction of large quantities of echinoderms has caused this destruction ( Figure 1.1). A large die-off of the sea urchin, Diadema antillarum, in the Caribbean Sea coin- cided with increases in algal growth in some areas but not others. | text | null |
L_0561 | importance of echinoderms | T_3062 | In some countries, echinoderms are considered delicacies. Around 50,000 tons of sea urchins are captured each year for food. They are consumed mostly in Japan, Peru, Spain and France. Both male and female gonads of sea urchins are also consumed. The taste is described as soft and melting, like a mixture of seafood and fruit. Sea cucumbers are considered a delicacy in some southeastern Asian countries. In China they are used as a basis for gelatinous soups and stews. | text | null |
L_0561 | importance of echinoderms | T_3063 | Echinoderms are also used as medicine and in scientific research. For example, some sea cucumber toxins slow down the growth rate of tumor cells, so there is an interest in using these in cancer research. Sea urchins are also model organisms used in developmental biology research. Sea urchins have been used to study the mechanisms of fertilization and egg activation, physiological processes that occur during early development, and the regulation of differentiation in the early embryo. In addition, the molecular basis of early development was studied in sea urchins. Gametes can be obtained easily, sterility is not required, and the eggs and early embryos of many commonly used species are beautifully transparent. In addition, the early development of sea urchin embryos is a highly conserved process. When a batch of eggs is fertilized, all of the resulting embryos typically develop at the same time. This makes biochemical and molecular studies of early embryos possible in the sea urchin, and has led to a number of major discoveries. | text | null |
L_0561 | importance of echinoderms | T_3064 | The hard skeleton of echinoderms is used as a source of lime by farmers in some areas where limestone is unavailable. Lime is added to the soil to allow plants to take up more nutrients. About 4,000 tons of the animals are used each year for this purpose. | text | null |
L_0562 | importance of insects | T_3065 | Many insects are considered to be pests by humans. However, insects are also very important for numerous reasons. | text | null |
L_0562 | importance of insects | T_3066 | Insects can be found in every environment on Earth. While a select few insects, such as the Arctic Wooly Bear Moth, live in the harsh Arctic climate, the majority of insects are found in the warm and moist tropics. Insects have adapted to a broad range of habitats, successfully finding their own niche, because they will eat almost any substance that has nutritional value. Insects are crucial components of many ecosystems, where they perform many important functions. They aerate the soil, pollinate blossoms, and control insect and plant pests. Many insects, especially beetles, are scavengers, feeding on dead animals and fallen trees, thereby recycling nutrients back into the soil. As decomposers, insects help create top soil, the nutrient-rich layer of soil that helps plants grow. Burrowing bugs, such as ants and beetles, dig tunnels that provide channels for water, benefiting plants. Bees, wasps, butterflies, and ants pollinate flowering plants ( Figure 1.1). Gardeners love the big-eyed bug and praying mantis because they control the size of certain insect populations, such as aphids and caterpillars, which feed on new plant growth. Finally, all insects fertilize the soil with the nutrients from their droppings. Bees are important pollinators of flower- ing plants. | text | null |
L_0562 | importance of insects | T_3067 | Insects have tremendous economic importance. Some insects produce useful substances, such as honey, wax, lacquer, and silk. Honeybees have been raised by humans for thousands of years for honey. The silkworm greatly affected human history. When the Chinese used worms to develop silk, the silk trade connected China to the rest of the world. Adult insects, such as crickets, as well as insect larvae, are also commonly used as fishing bait. | text | null |
L_0562 | importance of insects | T_3068 | Insects, of course, are not just eaten by people. Insects are the sole food source for many amphibians, reptiles, birds, and mammals, making their roles in food chains and food webs extremely important. It is possible that food webs could collapse if insect populations decline. In some parts of the world, insects are used for food by humans. Insects are a rich source of protein, vitamins, and minerals, and are prized as delicacies in many third-world countries. In fact, it is difficult to find an insect that is not eaten in one form or another by people. Among the most popular are cicadas, locusts, mantises, grubs, caterpillars, crickets, ants, and wasps. Many people support this idea to provide a source of protein in human nutrition. From South America to Japan, people eat roasted insects, like grasshoppers or beetles. | text | null |
L_0562 | importance of insects | T_3069 | Insects have also been used in medicine. In the past, fly larvae ( maggots) were used to treat wounds to prevent or stop gangrene. Gangrene is caused by infection of dead flesh. Maggots only eat dead flesh, so when they are placed on the dead flesh of humans, they actually clean the wound and can prevent infection. Some hospitals still use this type of treatment. | text | null |
L_0563 | importance of mammals | T_3070 | Mammals play many important roles in ecosystems, and they also benefit people. | text | null |
L_0563 | importance of mammals | T_3071 | Mammals have important roles in the food webs of practically every ecosystem. Mammals are important members of food chains and food webs, as grazers and predators. Mammals can feed at various levels of food chains, as herbivores, insectivores, carnivores and omnivores. Mammals also interact with other species in many symbiotic relationships. For example, bats have established mutually beneficial relationships with plants. Nectar-feeding bats receive a tasty treat from each flower, and, in return, they pollinate the flowers. That means they transfer pollen from one flower to another, allowing the plant to reproduce. Non-flying mammalian pollinators include marsupials, primates, and rodents. In most cases, these animals visit flowers to eat their nectar, and end up with pollen stuck to their bodies. When the animal visits another flower to eat the nectar, the pollen is transferred to that flower. Fruit-eating bats ( Figure 1.1) also receive food from plants. In return, they help these plants spread their seeds. When bats consume fruit, they also consume the seeds within the fruit. Then they carry the seeds in their guts to far-away locations. Zebras have been known to befriend ostriches. In this symbiotic relationship, both species benefit. The ostrich, with its terrible senses of smell and hearing and the zebra with its poor eyesight, are both able to warn the other when danger is near. The zebra can smell or hear certain dangers approaching, while the ostrich can see other dangers. Both are prepared to warn one another at a moments notice so they can each flee when necessary. Baboons and impala have a similar relationship. Impala are one of the most common prey species for all predators and need to be constantly alert. Impala have good hearing and eyesight, raising an alarm when danger is near. Baboons use trees to check for danger and bark an alarm when danger is sensed. What do the baboons receive? Male baboons sometimes prey on young impala soon after birth. So, though both alert others to dangers, sometimes this is not the best of relationships for young impala. Zebra and wildebeest are found together on the African savanna grazing different parts of the same grass. The zebra grazes the tougher parts of the plant, saving the softer parts for the wildebeest. A zebra will move into an area of tall grass before other herbivores and graze the grass down to the area that the wildebeest prefers. Bats, like this Egyptian fruit bat, play an important role in seed dispersal. | text | null |
L_0563 | importance of mammals | T_3072 | We see examples of mammals (other than people!) serving our needs everywhere. We have pets that are mammals, such as dogs and cats. Mammals are also used around the world for transport. For example, horses, donkeys, mules, or camels ( Figure 1.2) may be the primary means of transport in some parts of the world. Mammals also do work for us. Service dogs can be trained to help the disabled. These include guide dogs, which are assistance dogs trained to lead blind and visually impaired people around obstacles. Horses and elephants can carry heavy loads. Humans also use some mammals for food. For example, cows and goats are commonly raised for their milk and meat. Mammals more highly developed brains have made them ideal for use by scientists in studying such things as learning, as seen in maze studies of mice and rats. | text | null |
L_0563 | importance of mammals | T_3073 | Mammals have also played a significant role in different cultures folklore and religion. For example, the grace and power of the cougar have been admired in the cultures of the native peoples of the Americas. The Inca city of Cuzco is designed in the shape of a cougar, and the thunder god of the Inca, Viracocha, has been associated with the animal. In North America, mythological descriptions of the cougar have appeared in the stories of several American Indian tribes. Important mammals include Dolly the sheep, Lassie the dog, and flipper the dolphin. Dolly was the first mammal to be cloned from an adult somatic (body) cell, using the process of nuclear transfer. Lassie was a collie dog who appeared in seven full length feature films in the 1940s and 1950s, starting with Lassie Come Home in 1943. Additional Lassie movies were made as recently as 2005. Between 1954 and 1973, the Lassie television series aired, with plenty of additional productions as recently as 2007. Flipper was a bottle nose dolphin that starred in a television series between 1964 and 1967. The most famous mammal may be King Kong, the giant gorilla that terrorized New York City in 1933 in the movie of the same name. | text | null |
L_0564 | importance of mollusks | T_3074 | Mollusks are important in a variety of ways; they are used as food, for decoration, in jewelry, and in scientific studies. They are even used as roadbed material and in vitamin supplements. | text | null |
L_0564 | importance of mollusks | T_3075 | Edible species of mollusks include numerous species of clams, mussels, oysters, scallops, marine and land snails, squid, and octopuses. Many species of mollusks, such as oysters, are farmed in order to produce more than could be found in the wild ( Figure 1.1). Today, fisheries in Europe, Japan, and the US alone produce over 1 billion pounds of oyster meat each year. Abalone (a marine gastropod mollusk), a great delicacy, can fetch up to three hundred dollars per pound. Eating mollusks is associated with a risk of food poisoning from toxins that accumulate in molluscs under certain conditions, and many countries have regulations to reduce this risk. At certain times of the year, (usually the warmer months) many species of saltwater mollusks become very poisonous due to an algal bloom known as "red tide." The mollusks filter feed on the tiny creatures (called dinoflagellates in the bloom) that produce the toxins. Eating shellfish during a red tide can cause serious illness and even death to humans. Tastes in molluscan food vary tremendously from one person to the next and from culture to culture; however, when it comes to a question of survival, most mollusks are edible. Some are considered delicacies such as oysters and escargot (a snail that lives in trees), while others such as the clams and mussels of freshwater ponds and streams are less likely to be consumed due to taste, but none-the-less are very edible. Land-based mollusks are also eaten. France alone consumes 5 million pounds of escargot every year. Of course, some people are allergic to mollusks and need to be careful about consuming any kind of shelled animals. | text | null |
L_0564 | importance of mollusks | T_3076 | Two natural products of mollusks used for decorations and jewelry are pearls and nacre. A pearl is the hard, round object produced within the mantle of a living shelled mollusk. Pearls are produced by many bivalves when a tiny particle of sand or grit is trapped between the mantle and the shell. Its as if the mollusk has a splinter. The mollusk forms a protective covering around the irritant. Most pearls used as jewelry are made by pearl oysters and freshwater mussels; most of the ones sold are cultured and not wild. Natural pearls have been highly valued as gemstones and objects of beauty for many centuries. The most desirable pearls are produced by oysters and river mussels. The substance used to form the pearl covering is made from the mother of pearl material that lines the interior of the shell. Mother of pearl is also known as nacre. Nacre is the iridescent inner shell layer. It can be found in buttons, watch faces, knives, guns, and jewelry. It is also used to decorate various musical instruments. | text | null |
L_0564 | importance of mollusks | T_3077 | Several mollusks are ideal subjects for scientific investigation of the nervous system. The giant squid has a sophis- ticated nervous system and a complex brain for study. The California sea slug, also called the California sea hare, is used in studies of learning and memory because it has a simple nervous system, consisting of just a few thousand large, easily identified neurons. These neurons are responsible for a variety of learning tasks. Some slug brain studies have even allowed scientists to better understand human brains. Some octopuses and squid are incredibly smart. They are capable of learning to solve problems and do mazes. | text | null |
L_0565 | importance of protists | T_3078 | Humans could not live on Earth if it were not for protists. Why? Plant-like protists produce almost one-half of the oxygen on the planet through photosynthesis. Other protists decompose and recycle nutrients that humans need to live. All protists make up a huge part of the food chain. Humans use protists for many other reasons: Many protists are also commonly used in medical research. For example, medicines made from protists are used in treatment of high blood pressure, digestion problems, ulcers, and arthritis. Other protists are used in scientific studies. For example, slime molds (including D. discoideum, a soil-living protist) are used to analyze the chemical signals in cells. Protists are also valuable in industry. Look on the back of a milk carton. You will most likely see carrageenan, which is extracted from red algae. This is used to make puddings and ice cream solid ( Figure 1.1). Chemicals from other kinds of algae are used to produce many kinds of plastics. | text | null |
L_0566 | importance of reptiles | T_3079 | Reptiles play an important role in the life of humans. In addition to playing an important role in many food chains, which keep the populations of small animals under control, reptiles serve as food, pets, and have played roles in art and culture for thousands of years. | text | null |
L_0566 | importance of reptiles | T_3080 | Reptiles are important as food sources for people: Green iguanas, a type of large lizard, are eaten in Central America. The tribals of Irulas from Andhra Pradesh and Tamil Nadu in India are known to eat some of the snakes they catch. Cantonese snake soup is consumed by local people in the fall to prevent colds. The soup is believed to warm up their body of those who eat it. Cooked rattlesnake meat is commonly consumed in parts of the Midwestern United States. You can eat rattlesnake meat without worry of the poisonous venom. Other snake meat is consumed throughout the world. Turtle soup is consumed throughout the world. | text | null |
L_0566 | importance of reptiles | T_3081 | Reptiles also make good pets. In the Western world, some snakes, especially less aggressive species, like the ball python or corn snake, are kept as pets. Turtles, particularly small land-dwelling and freshwater turtles, are also common pets. Among the most popular are Russian tortoises, Greek spur-thighed tortoises, and terrapins. Large constrictor snakes like pythons, boa constrictors, and anacondas are powerful wild animals capable of killing an adult human, and they are commonly kept as pets. Many people dont think this is a wise idea, as these reptiles pose dangerous threats to people, especially children. Reptiles are capable of recognizing people by voice, sight and smell; many are capable of learning. Some species actually benefit from interaction with humans. When cared for properly, all live as long or longer than mammalian pets of similar size. Having a reptile as a pet, you get to learn about everything from adaptation, behavior and the environment, to nutrition, camouflage and reproductive strategies. Learning about the natural history and proper captive care of these animals just might change your world outlook and get you thinking more about the environment as a whole. Keep in mind that if you want to have a snake as a pet, that there are no herbivorous snakes, and you must be willing to feed it a proper diet. Be prepared to feed your snake, or other reptile, mice, rats, birds eggs, insects, or fish. And these need to be served raw. Of course, the herbivorous reptiles, such as the green iguanas and some tortoises, are much easier to feed. They eat foods such as chopped collard greens, romaine lettuce, chopped squash and bananas. | text | null |
L_0566 | importance of reptiles | T_3082 | Finally, reptiles play a significant role in folklore, religion, and popular culture. The Moche people of ancient Peru worshipped reptiles and often put lizards in their art. Snakes or serpents are connected to healing and to the Devil. Since snakes shed and then heal again, they are a symbol of healing and medicine, as shown in the Rod of Asclepius ( Figure 1.1). In Egyptian history, the Nile cobra is found on the crown of the pharaoh. This snake was worshiped as one of the gods. Reptiles have also played roles in more recent popular culture. Unforgettable reptiles include Leonardo, Donatello, Michaelangelo, and Raphael, otherwise known as the Teenage Mutant Ninja Turtles, and Godzilla, one of the most famous movie reptiles who has been terrorizing Japanese cities for years. Dino, from The Flintstones is one of the more lovable television reptiles. On the other hand is Nagini from the Harry Potter series. This tremendously long snake (roughly 12 feet) is difficult to forget as she was very important to Lord Voldemort. Though her appearances are far and few between, her unwavering loyalty to the Dark Lord makes her one of the more infamous reptiles. | text | null |
L_0567 | importance of seedless plants | T_3083 | Seedless plants have been tremendously useful to humans. Without these plants evolving millions of years ago, life as we know it would be very different. | text | null |
L_0567 | importance of seedless plants | T_3084 | The greatest influence seedless plants have had on human society is in the formation of coal millions of years ago. When the seedless plants died, became buried deep in the Earth, and were exposed to heat and pressure, coal formed. Coal is essentially made of the fossilized carbon from these plants. Now coal is burned to provide energy, such as electricity. | text | null |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.