Life in the Open Ocean
The open ocean, called the pelagic zone, is the largest area of the marine ecosystem. It extends from the coasts to the middle of the ocean and includes all areas above the ocean floor. The living things that survive in the open ocean need to have a way to float or swim in ocean water.
The area of the open ocean where sunlight penetrates, called the photic zone, is where most life is found. In the photic zone, drifting algae and other protozoa are able to use the Sun’s energy to do photosynthesis. They are the beginning of food chains in the open ocean.
Animals, protists, plants, and bacteria that float or drift in the open ocean instead of swimming are called plankton. They are moved around the open ocean by surface currents and wind. Phytoplankton are types of plankton that do photosynthesis like diatoms and other algae. Zooplankton are animals and one-celled protozoa that drift in the ocean water. Many zooplankton eat phytoplankton. Some zooplankton eat other types of zooplankton. Many are able to propel themselves only short distances through water to catch prey.
Animals that are able to move through the water are called nekton. In the open ocean there are many types of swimmers including fish, whales and other marine mammals, and sharks. Some fish, such as herring and tuna, swim in schools while others are solitary. Swimming in a school offers some protection from predators. Some nekton have other ways of moving besides swimming. For example, squid propel themselves through the ocean with a jet of water and flying fish are able to glide just above the water surface at up to 40 miles per hour using fins shaped like wings.
In the parts of the open ocean below where light can penetrate, there are fish and other living things like the elusive giant squid. Because there is no sunlight, there are no algae to start food chains. Instead many animals living in the deep ocean rely on the bodies of dead animals falling from the water above for food.
Bahari ya wazi, inayoitwa eneo la pelagic, ni eneo kubwa zaidi la mazingira ya baharini. Inatia ndani maeneo yote yaliyo juu ya sakafu ya bahari, kuanzia pwani hadi katikati ya bahari. Vitu hai vinavyoishi katika bahari ya wazi vinahitaji njia ya kuelea au kuogelea katika maji ya bahari. Sehemu ya bahari iliyo wazi ambapo nuru ya jua huingia, inayoitwa eneo la photic, ndiyo mahali ambapo uhai mwingi hupatikana. Katika eneo la photic, mwani unaosonga na protozoa nyingine huweza kutumia nishati ya Jua kufanya photosynthesis. Wao ni mwanzo wa minyororo ya chakula katika bahari ya wazi. Wanyama, mimea, na bakteria wanaotambaa au kuelea baharini badala ya kuogelea huitwa plankton. Zinasukumwa kuzunguka bahari wazi na mikondo ya uso na upepo. Phytoplankton ni aina ya plankton ambayo hufanya photosynthesis kama diatoms na mwani mwingine. Zooplankton ni wanyama na protozoa zenye chembe moja zinazotambaa katika maji ya bahari. Mnyama-mwitu wengi hula mimea ya mimea. Baadhi ya wanyama wanaoitwa zooplankton hula aina nyingine za wanyama wanaoitwa zooplankton. Wengi wao wanaweza kusafiri kwa umbali mfupi tu kupitia maji ili kuvua mawindo. Wanyama wanaoweza kusonga ndani ya maji huitwa nektoni. Katika bahari ya wazi kuna aina nyingi za waogeleaji kutia ndani samaki, nyangumi na mamalia wengine wa baharini, na papa. Samaki fulani, kama vile herring na tuna, huogelea katika makundi huku wengine wakiwa peke yao. Kuogelea katika shule hutoa ulinzi fulani dhidi ya wanyama-watu wanaowinda. Baadhi ya nektoni wana njia nyingine za kusonga mbali na kuogelea. Kwa mfano, samaki aina ya squid hujiendesha kupitia bahari kwa kutumia maji ya maji, na samaki aina ya flying fish wanaweza kuruka juu ya maji kwa mwendo wa kilomita 40 kwa saa kwa kutumia mabawa. Katika sehemu za bahari zilizo wazi chini ambapo nuru inaweza kupenya, kuna samaki na viumbe wengine walio hai kama vile squid kubwa isiyoeleweka. Kwa sababu hakuna mwangaza wa jua, hakuna mwani wa kuanzisha minyororo ya chakula. Badala yake, wanyama wengi wanaoishi katika bahari ya kina kirefu hutegemea miili ya wanyama waliokufa wanaoshuka kutoka majini ili kupata chakula.