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In vivo delivery of ssDNA
I am looking for a system with which I can deliver (large quantities of) ssDNA in vivo (say in mice). I do not know whether it is of importance but the 5' end of the ssDNA fragments are assumed to be phosphorylated.
If you could suggest some efficient delivery systems to me I would be very delighted.
Many thanks for your help in advance!

Small ssRNA  can be delivered in-vivo using a peptide from rabies virus (1, 2; it is quite specific to the brain, though). It should work with ssDNA as well but I don't know of an experiment that has tried it.

Electroporation!

Sure, that would be a possibility for cell cultures, but I am looking for a system that can do the job, for instance, in mice.

@Luigi how can someone perform electroporation in vivo?! :O

@user19099 In vivo electroporation is possible but it is very localized.

@user19099 In vivo electroporation is simple for intramuscular application, just inject the DNA, and then zap the muscle with the electrode. I've seen a paper that used an endoscope to do electroporation inside pig intestine with decent results. Not so good with intravenous injection though. What OP is asking is basically an entire research program.

@tobias The answer to this is anything but simple, and doesn't really exist yet. Many groups are working on non-viral methods to protect DNA and/or RNA in the circulation, target it to specific tissues, get it taken up efficiently, and then release the cargo in the right compartment of the cell. It's been challenging, and is far from finished. I would suggest looking at AAV, as its genome is ssDNA.

I would also look at hydrodynamic injection, which is good for delivery to hepatocytes, but not very practical for any other organ.

I agree with @user137 there are no easy answers - especially with 'large quantities'.  ssDNA material may even trigger innate immunity (eg Toll receptors/ interferon).  This recent work gives just one flavor of possible complications.


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Why does doing more physical labour reduce the prevalence of disorders like OCD?
This just an observation without any study backing it. But people who do more physical labour as opposed to sitting at the couch really do have less rates of OCD.
Why this association of physical work with OCD's?
By OCD, I mean Obsessive Compulsive Disorder.
Here's a study backing up the exercise and its positive effects on reduction of OCD,
https://www.ncbi.nlm.nih.gov/m/pubmed/17568300/

What is OCD? (And don't ask me to do an internet search, I'm on this website and I shouldn't have to wrestle with niche abbreviations. And how do you think anyone is going to answer a question about pre-agricultural man other than by speculation?

I edited out that question. And added details like full form of OCD.Is it OK now?

I retracted my close vote due to your edits, thank you. To improve your question, though, it would be best to have a citation for the claim "people who do more physical labour as opposed to sitting at the couch really do have less rates of OCD" - if this is just your own observation, then we can't really answer the "why." It's hard enough to answer "why" questions when there is a known effect.

@Bryan Krause. I can see my question was a horrendous one, I'm sorry bout that. I couldn't find any valid scientific citations backing up the labour claim but here's one backing up aerobic exercise.

I would first ask which way the causation works.  Does couch-sitting increase OCD, or do people with OCD prefer to be couch-sitters as a consequence of the OCD?

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


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Why does flatulence vary in temperature and smell?
Quite simply, why do some farts feel warmer than others?  Some feel regular, while others feel like lava.  What causes this?
If there is no real temperature difference, why do I perceive some to be warmer than others?  Does this contribute to the smell?  I've notice the hotter they feel, the worse they smell usually.

Burning sensation in the anus might also be related to decreased nerve function due to various causes including diabetes and vitamin b deficiency

a better question why would you think they would not?

Fundamentally, the smell of what comes out will depend on what goes in - primarily a function of what you ate and conditions in your gut (including the mix of bacteria).
In addition, if you ate something containing large amounts of capsaicin (the chemical that makes chili peppers spicy), it's going to "burn" on the way out. Aside from flatulence, overconsumption of capsaicin can irritate the intestines and cause diarrhea.

So you're saying the temperature fluctuates depending on the food you eat?  Does capsaicin affect temperature?

Capsaicin definitely affects the perception of temperature, but may cause localized irritation which in turn can raise actual (thermometer) temperature. Heat production is generally the product of metabolism; if something with large amounts of available energy ends up in the small intestine with sufficient bacteria to process it, expect tons of hot and obnoxious gas. If you're eating something that didn't have much of any energy in the first place, then there's nothing for the bacteria to metabolize in the first place.

I think the OP is asking about temperature in terms of the actual gas feeling warmer vs a burning sensation from capsaicin

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ID of a purple fungus in Virginia
Could someone tell me a bit more about this fungus found growing in a nearly straight line in the lawn in a wooded area of Virginia, USA? It seems rather fragile, maybe a bit "dry"

This is not a moss, but a fungus of the family Clavariaceae. Most likely this is Clavaria zollingeri, commonly known as violet coral, but there are a few resembling species. Microscopy might be needed to be entirely sure.
The species is saprotrophic, so it grows on the woody debris in your picture.


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What spider is this
Live in London I have this in my backyard. Want to know what kind is it...Also does it bite?

Please provide approximate size

May we get a view from the front? The eye pattern can be very helpful.

looks like a kind of wolf spider. legs not quite long enough for a dolomedes


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Stem and Branch of plants
What is the difference between the stem of a plant and the branch of a plant. Is the branch part of the stem?

Welcome to Bio.SE! What attempts to answer this question have you already taken? We ask that all question posters here attempt to search for an answer to their own question and explicitly indicate what research they've already done, what they learned, and what is still confusing or unknown to them. Our goal is not to simply be an answer site, but rather a site that promotes self-learning with some expert help along the way :). Please take a moment to edit your post with this additional detail, and it will likely be received more positively by our community. Thanks!

To answer this question, first, we must define the terms. Major primary plant organs can be characterized as either roots, stems, or leaves. A stem is a structure that contains nodes and internodes (as a previous answer explains), and axillary buds. These buds mean that stems can give rise to more stems, roots, or leaves.
Branches can be defined as stems arising from an axillary bud of another stem. In this way, all branches are stems, but not all stems are branches. Beware of confusing the botanical definition of branches (arising from axillary buds) from the colloquial definition of a branch (a tree branch) because... all tree branches arise from axillary buds, but not all botanical branches are found on trees!
Hope this helps!


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What is this plant, and should the lowermost leaves be curling up?
We've got a couple of these plants but have no idea how to look after them. Watering them regularly (every 2-3 days, or when the soil seems dry) seems to help. The pot rims are about a foot at their widest part.
However, we're concerned about the lower leaves drying up. Is this a normal part of this plants growth process and does it continue this way and produce a 'trunk' of sorts?
As a follow on question, do we need to re-pot these plants?

I think you are likely to find more knowledgeable help at Gardening.stackexchange

I may be wrong, but I believe these are two Foxtail Agaves (Agave attenuata). These resources may help you take care of them.
Foxtail Agave Care Information
And for the wilted leaves:
How to Save a Dying Agave Plant
Also, the Gardening SE may be able to help more.
Hopefully this helps!


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What species is this cocoon?
I found this cocoon outside my house and I want to know what insect might be inside it and it’s species. Please help!
I found it a day ago when it was a worm, now its a cocoon, it’s like outside the main entrance (which is like 2 metres high) and the cocoon was half way on the left, and it was out in the sun, to be honest I’m surprised little kids didn’t kill it yet.
I live in Kuwait in a town called Hadiya.
I don’t see many worms in Kuwait, I’ve only seen like 4 in my whole life.

Hi, and welcome to the site!  In order to be able to identify it, we'll probably need more information - where do you live?  You found it recently, I presume?  Also, a more precise description of the environment in which you found it could be helpful: "outside my house" leaves a lot of unanswered questions: how high? it looks like a painted surface?  Is it in the shade or in full sun?  Please [edit] to include more detail.  Thanks!


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What is this spider found in Brittany?

I found it in Brittany, in my kitchen. It was about 3cm in width and 5 in length.

Is it dangerous ?

How big is the spider? What sort of behavior did you observe? Where specifically did you find it - indoors or outside, in a bush (what kind?), under a rock, in the forest, on the beach...? Do you have multiple images from different directions? Did it bite or pinch, and if so, what was the reaction, if any? The more information you can provide, the better, especially if you have multiple clear images.

This is likely a hackledmesh weaver of the genus Amaurobius. There are several species in the area.

I agree with JimN - this appears to be one of the cribbelate ground spiders in the Amaurobius group.  The defensive position of the forelegs is pretty standard, and the rather diffuse abdominal pattern is also consistent.
Here's a picture of the common worldwide species Amaurobius ferox for comparison:

These spiders and their relatives can give a painful bite, but the venom is essentially harmless to humans.
It's not easy to make out from the photo, due to the light and shadow effects, but I suspect that yours is a male - which might explain why the spider ended up in one of your kitchen cabinets if there wasn't any fluffy silk nest/shelter/snare nearby.
Male spiders can be identified by the enlarged ball-like devices at the ends of their pedipalps (the "face arms" which hang like little legs in front of the face).  They're just looking for love and if left to their own devices will wander off after females for the relatively short time they have left to live.


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What type of insect/bug is this?

Bug I found on my hood of jacket After being at a friend's house.

Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.

Species ID questions are expected to include:
One or more clear Photos
A Location where the specimen was found (city/region and habitat)
An approximate Size (or photo indicating size)
Additional useful info (e.g., behavior, time of day/year, etc...)


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Peruvian insect identification
The above is an insect I found while visiting Peru. I’m no biology expert, and I was just curious to know what species of insect this was. I found it on a rock while exploring the ruins near Pisac, if that helps.

Looks like a Megaloptera juvenile.

Definitely not Megaloptera. Looks like a lampyrid (firefly) larval or female form. Note especially what look like single tarsal claws (on the end of the feet). This is diagnostic for Lampyridae (Coleoptera).

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Identification of a spider

I have found this 8mm spider in my home, North London. I've been told it may be a false widow but wanted a second opinion.
Note: The silvery parts in the picture are actually brownish in colour

It does appear to be a young spider, and seems consistent with a young Steatoda of some sort, so "False Widow" sounds OK.
Edit:  I just did a quick Google search and pulled up a useful paper (link below) that pretty clearly indicates that this is almost certainly a young Steatoda nobilis, one of the 'False Widows'.  See the top left - image A

Dugon, M.M., et al. 2017. Occurrence, reproductive rate and identification of the non-native noble false widow spider Steatoda nobilis (Thorell, 1875) in Ireland. In Biology and Environment: Proceedings of the Royal Irish Academy 117(2):77-89


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What type of bug cocoon is this?
My question is about these cocoon like things that are all over my house and fence in Florida (USA).

FL being Florida? Or Flanders? Why do Americans always assume... Ah, forget it.

@RHA It does not matter, these moths would be the same everywhere. And if you really want to know the answer to your question, it is because America is huge, and surrounded by only 2 other countries. Most Americans live a great distance from the border of these two countries. It is equally arrogant to assume that Americans are uniquely insensitive. People are the same, regardless of where they live, and are shaped by the circumstances that surround them (like geography)

It does matter, one should always be clear about location. See https://biology.meta.stackexchange.com/questions/3452/are-there-any-guideline-about-species-identification-questions

Related: https://biology.stackexchange.com/q/51252/16866

That is a bagworm. Order Lepidoptera, family Psychidae. You can read about them here https://en.wikipedia.org/wiki/Bagworm_moth


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Mystery bug photographed in Brasil

Shot in Brasil.  Anybody know what it is called!!?

Hazarding a guess here: you've got a true bug that's about to take flight. Given that event, I don't think the evidence at hand is enough to go deeper.

From this photo (beautiful shot, btw!) you can see that it must be a true bug - admittedly, the diagnostic characteristics are hard to spot, but I will try to walk you there.
Most apparently, we see an insect (six legs) with sucking mouthparts. Admittedly, the rostrum is hidden behind the bucculae (for an explanation of the bucculae compare this graphics here and here).
But besides the bucculae, the absence of chewing/biting mouthparts is apparent.
We further see long, segmented antenna, sclerotized forewings, a considerable pronotum and a dorso-ventrally flattened abdomen.
From the entirety of these characteristics, we can conclude it must be a true bug.

True bugs are divided into seven infraorders, of which three are (semi)aquatic (Gerromorpha, Leptopodomorpha and Nepomorpha), one comprises only miniature species (Dipsocoromorpha) and one comprises only ground-dwelling, cryptic species (Enicocephalomorpha).
The two remaing infraorders are ideally distinguished by microscopic dissection (compare the detailed Wikipedia articles in German for Cimicomorpha and Pentatomomorpha), but from experience, I think it must be a Pentatomomorpha.
With this knowledge, I run an inverse Google search on the photo - caution: this is not best practice in species identification - what to my surprise already correctly identified the specimen as a true bug.
Among the images (whereof several were arbitrary red-colored insects) was an image of Sphictyrtus chrysis on iNaturalist, that looks very similar to the photographed specimen. Besides the habitus, this would be the:

black forewings
black pronotum with red margins
black antenna with a club-shaped last segment
black legs
red head with black eyes
dorsal segments red with black margins with a thin, white line

According to GBIF, S. chrysis seems to be common in eastern South America, including Brazil.
There is the possibility that similar species (maybe even from the same genus Sphictyrtus) exist in Brazil, but this is the best I could infer from this photo as someone unfamiliar with the South American true bug fauna.


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Is this is a parasitic wasp, which I found in Blackpool Lancashire?
A wasp I photographed on my van window in Blackpool just before it attacked me.
Is it true that it’s rare to see them in the UK?

Excellent picture!  Someone will know this species.

Yes it is ! If you look closely at the wing patterns, they are characteristic of the Ichneumonidae family, as you can see below*. This family contains thousands of species which all are parasitoids. Species identification is very tricky for this family, but the patterns on the abdomen (2nd and 3d strips are yellow, the others are black, yellow spot at the tip) and on the tibia (yellow strips) are very characteristic of the species Ichneumon stramentor, which parasitizes caterpillars.

Based on the width of the abdomen, this is probably a female (ovipositor is not visible for this species).
It's actually quite common in the UK (they live in habitats such as hedgerows or woodlands), but not so frequently seen on windows!

*Image source : DrawWing.org
Derived from: Comstock J.H.
(1918) The wings of insects. The Comstock Publishing Company, Ithaca, N.Y.

Can you please provide the source of the image?


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can magnesium bicarbonate be absorbed in the mouth?

Can Magnesium Bicarbonate be absorbed in the mouth?"
  Magnesium Bicarbonate occurs naturally in some mineral waters.

Why did you tag this question with "genetics", "evolution" and "cell-biology"? Does this indicate you are expecting answers that are related to these fields?

Is it important for you to know that magnesium bicarbonate is absorbed in the mouth or, for example, in the small intestine, where most of the minerals are usually absorbed? Also, what you have found yourself, so far?

Technically, the human mouth do not absorbed anything. The human mouth is just a first line of defense mechanism against external microbial (In terms of saliva). If in terms of physical aspect, it just helps you to reduce food size and shape it for consumption.
Real absorption do not happen in the stomach neither. Stomach is where acids are used to break down your food and subject to higher lethal effect to kill microbial. The absorption only begins in the small and large intestine. (This is why drug delivery is such a hot topic in research labs).
To answer your question, yes. We need magnesium to survive and so we do absorb magnesium. In fact we can't live without magnesium, we need it for certain vital functions for our body to be normal. (Only in small magnesium amount, we don't need a lot of it).
As for bicarbonate, our body do not need it. In small amount, it is not toxic to our human body but in high volume, this would be a serious issue. When we breath, on cellular level, gas exchange occurs. Oxygen is supplied into our healthy cells while carbon dioxide is removed from our cells into our blood.
This is where it gets tricky, we do not store carbon dioxide in the form of gas when removing it via breathing out. We actually store carbon dioxide in the form of Bicarbonate in the plasma of our blood (Do note that its plasma, not RBC). When it is transported to our lung, this bicarbonate will be converted to CO2 and removed as we breath out. Hence, we do not absorb bicarbonate unless it reacted with some other elements or salt to produce some byproduct that we could use.
I hope you find this useful.
Regards
Price

Thank you. So what about mineral waters containing magnesium bicarbonate?
Duman


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Need help with these invasive vines damaging trees causing tree limbs to break
I need some help identifying various vines growing and girdling trees:

Please review the guidelines for writing a good species-identification question. At the very least, you should include your location, the size of your vines, and any closeup images you can (including any you may have of any of the vines' leaves). Please update to enable a good answer (and to avoid having your question downvoted and closed). Thanks!

Looks like Kudzu from afar. Very hard to manage,IMO , but not impossible. Cut and apply systemic herbicide to the cut stems, perhaps. You'll need to hit the growth a few times, otherwise all you can do is cut it back and wait for it to re-grow.


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Why is photosynthesis described as a "physico-chemical" process?
In my textbook it is given that photosynthesis is a physico-chemical process. How can it  be a physical process?

All chemistry is physical, physico-chemical genergally means there is something besides just atoms interacting is happening, in this case light absorption as a fundamental part of the reaction.

Preamble
This question appears to be based on the false premise that the ‘physico’ component of the word ‘physico-chemical’ has that meaning of the word ‘physical’ that relates to bodily activity. It does not. It refers to ‘physics’ and physico-chemical has the meaning of ‘relating to physics and chemistry’.
I had pointed this out in a comment, suggesting that the question should therefore be closed. However this has not happened, my comment has been deleted, and one of the moderators has implied approval of the question by providing an answer. In these circumstances, and because I disagree with the answer from @WYSWYG I have felt obliged to provide an answer of my own.
What is the question?
The question in the body of the text relates clearly to the meaning of the word physico-chemical. It is necessary to define it first to point out the false premise on which the question is based. The title asks a slightly different question — “why photosynthesis is a physico-chemical process?” — which does not entail this premise, and which I shall attempt to answer.
Meaning of ‘physico-chemical’
Oxford Dictionary

“Relating to physics and chemistry or to physical chemistry.”

This, incidentally, as the definition Google uses (without attribution) when you search for the term.
Collins English Dictionary

“Of, concerned with, or relating to physical chemistry or both physics
  and chemistry”

And, although it is the poster — rather than the unnamed textbook — who uses the term ‘physical’, it is worth pointing out that the latter adjective can have at least three meanings in English, the third of which is given by the Oxford Dictionary as:
“Relating to physics or the operation of natural forces generally.”
So that the use of this word without further clarification is ambiguous.
Physics and Chemistry are regarded as different
Although there are interfaces between different scientific disciplines, I do not regard statements such as that made in another answer — “all processes are basically physical” — helpful in explaining the physico-chemical nature of photosynthesis. Indeed, the very use of the adjective implies that the two are generally regarded as different. Dictionary definitions of scientific concepts are not always correct, but the following seem reasonable:
Physics

“The branch of science concerned with the nature and properties of
  matter and energy.”

Chemistry

“the branch of science concerned with the substances of which matter
  is composed, the investigation of their properties and reactions, and
  the use of such reactions to form new substances.”

Why is photosynthesis a physico-chemical process?
To quote the title of the first section on photosynthesis in the 6th edition of Berg et al. Biochemistry:

“Photosynthesis converts light Energy into Chemical Energy”

The study of light belongs to the realm of physics — its wave and particle properties, its reflection, refraction, polarization, diffraction etc. Biological metabolic chemistry usually involves the interaction of molecules to form different molecules. Of course it has a physical (= related to physics) component in that it obeys the laws of thermodynamics, it involves the activation energy of molecules, and the flow of electrons. But how photosynthesis is different — why the author took the trouble to point out that it was a physico-chemical process — is because it is the energy of light — of a photon — that drives the thermodynamically unfavourable chemical reactions.
The details of photosynthesis are complex, but the following figure from Berg et. al. illustrates the essential concept:

[Fig. 19.2 Light is absorbed and the energy is used to drive electrons from water to generate NADPH and to drive protons across a membrane. These protons return through ATP synthase to make ATP.]
The energy of photons of light is being used to split water and reduce NAD+ to NADH. This is different from e.g. the normal cellular reactions that reduce NAD+.
Footnote: The terminology of other ‘physicalities’
Nomenclature in biological sciences is fluid, but it may be worth mentioning the current terms in use for other biochemical processes in which the term ‘physical’ has more to do with “Involving bodily contact or activity” than physics.

If the poster had thought of ‘physical’ in terms of things like muscle contraction, biomechanics is perhaps the term to use.
In his answer @WYSWYG seems to suggest that the rotation of the ATP synthase may be what the text meant by physico-chemical. The term normally used to describe ATP synthase is molecular motor. In any case the ATP synthase is not unique to photosynthesis.

You are welcome to disagree with an answer and provide a better one. However, your answer need not include the history of the activity on the question/comments, your opinion on what the other user thinks about the question and the mention of the status of the other user as a moderator. These are irrelevant. BTW, I deleted your comments (also that of the other user) because they were getting chatty/personal. I guess that a lot of your comments follow this trend and it is better if we can restrict the comments to just the technical aspects of the post.

@WYSIWYG I felt I had to explain my position as I had previously commented that I regarded the question as trivial. Nor did I wish to discourage others from adding to the two close votes. I still feel embarassed about answering. I regard it important to make it clear where my answer differs from another so that the reader can see there is a conflict of opinion that requires him to make a judgement or conduct research. As long as no personal remarks are made I can see nothing in SE rules that this violates. Also, please note, I am not contesting your decision to delete my comment.

Well, all processes are basically physical.
If you search "physicochemical processes" in NCBI Medical Subject Headings it displays the page on "Chemical Phenomena" which is defined as:

The composition, structure, conformation, and properties of atoms and
  molecules, and their reaction and interaction processes.

Also, this website (Reference.MD) defines it as:

Physical reactions involved in the formation of or changes in the
  structure of atoms and molecules and their interactions.

In any case, there are several "physical reactions" (reactions that do not involve making and breaking of chemical [covalent] bonds) happening during photosynthesis.
These would include:

Movement of protons and electrons
The rotation of the ATP synthase
Absorption of light by the photosystem and activation of the reaction center.


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Egypt bug needs identification please
Is it possible to identify this bug,,? Found in South Sinai  .in Egypt . Only seen crawling but maybe it can fly ? Black with 6 legs. 2 long black "strings " coming from back end
Thank you

Are you sure the 2 long black "strings" are from the back? Looks more like an antenna to me, and the larger legs are usually on the back.

Please update with approximate size and a picture of the other side of the specimen. Thanks

This is a cricket in the family Gryllidae. The two thin "strings" on the left are antennae, and the two sturdier "strings" on the right are cerci (though your image is not clear, and perhaps one of the extensions on the right is actually an ovipositor). See here for a clear image showing cricket anatomy.
An example cricket with wide geographic range that includes Egypt:
Gryllus bimaculatus

 Credit: Vlad Proklov
Without additional info, I'm not sure you'll get an accurate species ID on your specimen.

All photos on this question are of female specimens (yes, that is an ovipositor on the right; the right cercus is also visible just below, but somewhat out of focus); given that species level identification in singing insects is at least assisted by a recording of the male calling song, the best anyone will be able to do is give a genus (assuming access to the specimen and the appropriate identification keys).

Thanks for the informative follow-up, Arthur.


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Is reverse senescence/"anti-aging" actually scientifically possible among humans yet?
I have been very interested in this since I myself am interested in reversing my skin's aging/genes/damage/etc. I also am interested in volunteering any future genetic altering of skin quality.
Basically I've heard of experimental drugs called senoyltics that are believed to (and have actually done so) have the ability to truly reverse aging at the cellular level and/or aging damage of skin and etc.
I am very intrigued and want to know if this is feasible for humans yet -- or any such breakthroughs. I really want my skin's genetic quality to be enhanced, but reversing aging damage by genes will suffice.
So skin aside, in general, is reverse senescence (with or without senolytics) anywhere near possible to reach human success? I've heard of labs and etc. working on this for testing, but nothing more.
My question is basically: is it possible? Are we really in the near future to reversing aging in humans?
As a note: I don't mean "anti-aging" as in preventing death -- more so as in making yourself younger in a myriad of ways, such as by appearance and physical ability (like heart; brain; skin texture/youth; etc.)

 Short Answer
You might be interested in learning about telomeres, telomerase, and telomerase gene therapy.
For example, Boccardi & Herbig (2012): describe a mouse study in which they used telomerase gene therapy to improve the healthspan and lifespan of mice by up to 24%.
As far as I know, we have no successful human trials of similar therapies that have targeted and succeeded at "decreasing the age" of humans.

However, this source does claim that a woman attempted to do so. I cannot substantiate these claims in any way, so I'm skeptical at best...

 Long Answer:
Telomere 101:
Telomere: non-coding nucleotide sequences on the tips of chromosomal DNA strands.

Due to the inability for DNA polymerase to replace RNA primers on the end of linear strands of eukaryotic DNA during DNA replication, ~50-100 base pairs are removed from the daughter strand from each replication event.

The "junk" (i.e., non-coding) telomere sequences (which could repeat 1000s of times) provide buffers against losing more valuable DNA when this happens. Eventually though, the telomeres run out, and replication events could lead to loss of coding regions of DNA...
According to Boccardi & Herbig (2012):

As we age, telomeres in most of our tissues progressively become shorter and therefore likely contribute to the failure of our organs and tissues observed in old age. Supporting this are data demonstrating that healthy lifespan is positively correlated with longer telomeres in humans, and patients suffering from age‐related diseases and premature aging syndromes display shorter telomeres compared to healthy individuals (Zhu et al, 2011).

The enzyme, telomerase can replace these telomeres, but telomerase is really only active in stem cells and white blood cells, so most adult cells lack this regeneration ability.
This is where telomerase gene therapy  comes into play.

In the simplest sense, this approach attempts to artificially add telomerase to adult cells to essentially add back telomeres and potentially slow or even reverse the aging process.*

 *Note: As far as I know, we don't actually know whether short telomeres are simply an effect of aging or if they are actually the cause of aging (and ultimately death), so this gene therapy is running on a relatively unsupported hypothesis.
For example: Boccardi & Herbig (2012) "Telomerase gene therapy: a novel approach to combat aging".

They found that adding telomerase to 1 year old mice increased their lifespan by 24%.

 Credit: Boccardi & Herbig (2012):
As Boccardi & Herbig (2012) note, however, applied human studies are still a thing of the future.

While these studies provide a proof‐of‐principle that telomerase gene therapy is a feasible and generally safe approach to improve healthspan and treat disorders associated with short telomeres, a clinical application in humans is likely still some time away.

However, this source does claim that a woman (Elizabeth Parrish, CEO of Bioviva USA Inc. -- notice the website :p) attempted to do so -- I cannot substantiate these claims in any way, so I'm skeptical at best...

Citations and additional suggested reading:

Boccardi, V. and Herbig, U., 2012. Telomerase gene therapy: a novel approach to combat aging. EMBO molecular medicine, 4(8), pp.685-687. read here

Campisi, J., Kim, S.H., Lim, C.S. and Rubio, M., 2001. Cellular senescence, cancer and aging: the telomere connection. Experimental gerontology, 36(10), pp.1619-1637. read here

Zhu, H., Belcher, M. and Van Der Harst, P., 2011. Healthy aging and disease: role for telomere biology?. Clinical Science, 120(10), pp.427-440.

So wait. I'm confused. Is telomerase gene therapy the same concept as "skin age" as a separate component from skin appearance/quality? Because people can be young with shorter telomeres and have poor quality skin, and the reverse can be true as well. So how will telomerase therapy impact skin quality itself as a genetic component in the whole process? I'm asking because the rats shown appear to look younger/more youthful in these gene experiments. So I'm unsure if "reverse aging" by telomeres functions as the same idea of looking more youthful and/or the skin's quality and texture/form overall

Keeping in mind that this was a very small, not especially well-controlled preliminary/exploratory study. Because life expectancy was increased by ~2.5 years - or got ~2.5 years younger biologically, depending on how you look at - it is the reason that this study is being talked about at all.
In the TRIIM study 9 men, ages 51-65, first took hGH alone (0.015 mg/kg, or ~3 IU for a person weighing 70 kg) 3-4 times per week for one week and then added DHEA (50 mg) the next week, similar to Fahy’s n=1.  The week after that, the same doses of hGH and DHEA were combined with metformin (500 mg). At the start of the fourth week, the doses were individualized based on each participant’s particular responses. (To put the hGH dosing into context, while it’s individualized, athletes using it for performance enhancement may take 10-25 IU 3-4 times a week and “longevity” clinics may prescribe somewhere in the ballpark of 1-2 IU/day.) The goal of this titration approach was to maximize IGF-1 and minimize insulin by varying each of the hormones and drugs.
The investigators reported a mean “epigenetic age” approximately 1.5 years less than baseline after the 1-year intervention. In other words, their epigenetic age got 1.5 years younger while their chronological age obviously went up another year (total 2.5 years taken off).
On a side note, after 1-year of treatment, there was “highly significant” evidence of restoration of thymic functional mass along with improvements in age-related immunological parameters, based on MRI imaging and favorable changes in monocytes and T-cell changes.
Reference: https://www.nature.com/articles/d41586-019-02638-w
Also, reversal of epigenetic changes with OSK (part of Yamanaka factors) is very promising. This paper is worth reading - https://www.biorxiv.org/content/10.1101/710210v1

Not within the next two decades, at least (assuming you meant nearly total reversal of the effects of physiological aging). Any further than that is impossible to predict, since we are likely only a few breakthroughs away at this point (however, with extremely bad luck, these could take centuries to achieve, since presumably no scientist knows the 'optimal route' to developing these types of therapies at this point). But it is certainly possible from a scientific point of view.
While this is slightly off-topic, since you seem particularly concerned with skin aging, I would suggest protecting the stem cells of the skin from mutagens. These include UV radiation (which comes not only from the sun, but also from blue sky), background radiation (which depends on altitude and geographic location (inc. North American examples)(similar maps for Europe)) as well as lipid-soluble volatile genotoxins such as benzene and PAHs, which arise from the combustion of organic matter (e.g. wood burning, smoking, conventional BBQ grills, car exhaust).
Other factors that affect aging of the skin are the factors that degrade collagen, including UV radiation (again) as well as high blood sugar, which in turn triggers the formation of advanced glycation end-products that reduce collagen elasticity. One more factor associated with skin aging is particulate air pollution (Ding et al. 2017), which damages the DNA as well as other cellular structures by inducing oxidative stress (Piao et al. 2018). Particulates also often have genotoxic compounds adsorbed onto their surface (see e.g. Jia et al. 2017)).
Currently, the most effective way to prevent skin aging is to minimize exposure to the factors mentioned above. Many of these factors also promote certain other processes associated with aging (the accumulation of DNA damage causes cancer and accelerates stem cell aging (Rossi et al. 2007), whereas exposure to particulates is expected to contribute to the development of brain diseases such as Alzheimer's (Maher et al. 2016))
I would expect DNA mutations of the skin to be relatively easy to fix, though. For example, the skin is relatively accessible, so stem cell therapy could certainly work, as could a Cas9-based therapy used to strategically fix specific key mutations to prevent senescence. Presumably research to this end will be conducted relatively soon, now that Cas9 has gained popularity in the scientific community.
References:
Ding, Anan, et al. "Indoor PM 2.5 exposure affects skin aging manifestation in a Chinese population." Scientific reports 7.1 (2017): 15329.
Jia, Yi-Yang, Qi Wang, and Te Liu. "Toxicity research of PM2. 5 compositions in vitro." International journal of environmental research and public health 14.3 (2017): 232.
Maher, Barbara A., et al. "Magnetite pollution nanoparticles in the human brain." Proceedings of the National Academy of Sciences 113.39 (2016): 10797-10801.
Piao, Mei Jing, et al. "Particulate matter 2.5 damages skin cells by inducing oxidative stress, subcellular organelle dysfunction, and apoptosis." Archives of toxicology (2018): 1-15.
Rossi, D.J., Bryder, D., Seita, J., Nussenzweig, A., Hoeijmakers, J. and Weissman, I.L., 2007. Deficiencies in DNA damage repair limit the function of haematopoietic stem cells with age. Nature, 447(7145), p.725.


text:
Unknown mite species in plant pots
Does anybody know what kind of mite this is?
It is living in my pepper plants' pots.
My region is south of Germany. (Baden-Württemberg)
I will try to take another picture including some size measurement today.

Update:
As suggested by @theforestecologist, I added pictures including a size bar.
Thanks to @tyersome, I managed to merge my two accounts now.

Hi Icke. Nice pictures! Could you please [edit] your question to include your location, what type of plants you found them associated with,  and an approximate size of the specimens. You'll get a much better answer that way. Thanks.

Since you seem to be posting using two separate accounts, you may find this information on merging accounts to be of interest ...

These look a lot like dust mites, a collective term to describe cosmopolitan house-dwelling mites in the Pyroglyphidae family.

The most common species in temperate regions belong to the Dermatophagoides genus, including D. pteronyssinus (the European house dust mite) and D. farinae (the American house dust mite).

 source: Wikipedia

See here for a closeup of D. pteronyssinus

Alternatively, they may be "storage mites" belonging to the Acaridae family, which are another group of common dwelling-inhabiting mites that are more often found in stored foods vs dust, upholstery, or carpeting.

Lepidoglyphus destructor is one such example but that is also found to be present in dust [Source: Juliá et al.(1995)]. Another common storage mite, Tyrophagus putrescentiae typically eats mold, and could be found outside a food setting if the mold density was prevalent enough.

 L destructor (according to M. Deml on biolib.cz)

I'll note that there are hundreds of mites in these two families of mites alone, so someone may be able to get to a more specific species for you. Knowing more about where you found them (species of plants, etc.) may or may not help narrow down more specifically. For example, the person in this forum post found a very similar looking mite on their pots as well (see here).

Description:

Both male and female adult house dust mites are globular in shape, creamy white and have a striated cuticle. The female measures approximately 420 microns in length and 320 microns in width. The male is approximately 420 microns long and 245 microns wide.  [Source: UFL.edu]

Human impact:
The genus name Dermatophagoides means "skin eater," but these mites are not parasitic. Their diet mainly consists of eating dead skin flakes from mammals (and some birds).  Human detritus is one of the primary food sources for these mites, and so it's no surprise that they are often associated with dust in human dwellings.
So these mites don't bite humans or burrow into their skin. However, they do tend to have a negative impact on humans. Specifically their digestive enzymes remain in their feces, and these dried fecal enzymes (along with their dried dead exoskeletons) cause allergic reactions in people. In fact, according to Raulf et al. (2015), 20 allergens are known from just the two species of hdust mites mentioned above!
From UF IAFS

Mite allergens are mainly present in feces of house dust mites and may become airborne and inhaled by patients, giving rise to asthma, rhinitis, or atopic dermatitis

In fact, the family name, Pyroglyphidae, which literally means "fire + carve", seems to be related to the "burning itchy" eczema that some people develop that results in lots of scratching (carving :p).

Multiple sources suggest that storage mites often have similar allergic impacts as dust mites. Fro example, this site suggests:

In Europe, Lepidoglyphus destructor has been reported to be a major source of mite allergy in rural and urban environments

The question is, how many people are impacted?

Well, according to studies cited again by Raulf et al. (2015) that examined 7000 Germans found that  ~16% had a sensitization to D. pteronyssinus. Other studies (discussed in Hossny et al. (2014)) seem to suggest much higher prevalence in certain populations -- with sensitivities found in up to 90% of people tested from certain populations.

What can you do??
According to UF IFAS:

To manage mite populations, reduce the humidity below 70% and thoroughly vacuum mattresses, carpets, sofas, and chairs. Very sensitive individuals should encase their mattresses in plastic. Use drapes that can be washed and change bed clothing frequently. Vacuuming does not always remove all the live mites and Korsgaard (1982) stresses reducing humidity over sanitation. No one method has been found for reducing mites and relieving allergy suffering. Immunotherapy, i.e., injections of mite extracts into the patients to increase antibody level, has had variable success (Munro-Ashman et al. 1976).

Final word(s):

I'll just mention that there is a ton of literature about these mites and their impacts on humans, so if you're interested, DIG IN!

The [Major Mite Taxa] key by D. E.  walter (find at idtools.org](http://idtools.org/) is an excellent online resource for digging into mite identification further!

Citations:
Hossny, E., El-Sayed, S. and Abdul-Rahman, N., 2014. Sensitivity to five types of house dust mite in a group of allergic Egyptian children. Pediatric allergy, immunology, and pulmonology, 27(3), pp.133-137.
Julia, J.C., Martorell, A., Ventas, P., Cerda, J.C., Torro, I., Carreira, J., Guinot, E., Sanz, J. and Alvarez, V., 1995. Lepidoglyphus destructor acarus in the urban house environment. Journal of investigational allergology & clinical immunology, 5(6), pp.318-321.
 Raulf, M., Bergmann, K.C., Kull, S., Sander, I., Hilger, C., Brüning, T., Jappe, U., Müsken, H., Sperl, A., Vrtala, S. and Zahradnik, E., 2015. Mites and other indoor allergens—from exposure to sensitization and treatment. Allergo journal international, 24(3), pp.68-80.

@Icke with more specifics (i.e., provide the details I requested in my comment above) we oculd try to make a more definitive ID.


text:
What spider is this? BOLIVIA

I was in Cobija in northern Bolivia, and these spiders were hanging around a lamp post. There were over 100 of them.
The picture is not a good one, but I can describe them:

They were black with light blue stripes on their body, and the legs were black and yellow. They formed a big X with their legs.

Anyone know what spiders these are?

Read your text twice because others will read it 10-20 times, for words like spiser and picrure, it's a good forum to learn how to say things tactically without resorting to adding S on vocabularys.

The size, shape and leg arrangement as it hangs upside-down in the web, marks this spider as an Argiope, as previously noted.  The big white band on the front of the abdomen suggests A. argentata, but the photo is blurry enough that some of those spiders might be A. trifasciata.  I'd be happy to put it down as Argiope species, in the hope that more, and closer photos of this neat and completely harmless (to humans) spider are forthcoming.

https://bugguide.net/node/view/2033

Again, thanks for your expertise in spiders, John, but please provide support and provide citations for images (preferably those from reputable sites that properly ID the species you include). Thanks!

What’s with them hanging out in numbers like that?

The normal reason for finding lots of relatively solitary spiders in an area is that there's lots of food there.  Anywhere near a light source is a good place for flying insects, depending on the surrounding area.  I've seen closely packed webs on a lighted bridge over a canal, for instance.  There needs to be some sort of support structure as well, for the spiders to anchor the webs to; the photo is fuzzy enough that whatever is there is hard to see, but I would assume a wire fence or some other wire structure serves as the base that the webs are attached to at the top.

The interesting thing to me about this photo, and thanks for the question, Melanie, is that we would expect to see this sort of congregation around a light source for night-hunting spiders, like the usual Araneid orbweavers.  Argiopes, in North America, at least, are mainly day-hunting spiders - which may be a factor in their practice of making those center stabilimenta in the webs.  You wouldn't expect a light source to be all that important to spiders that operate their snares in the daytime.  Perhaps something else is going on, or perhaps these spiders have learned that night is better.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Is there a double helix RNA?
I wonder what is its function and if it can be the genetic material for a living organism. If not, why?

Yes, double-stranded, helical RNA exists. It can occur naturally, a famous example would be Rotavirus, as well as synthetically in the lab.
Please note, however, that viruses strictly speaking do not qualify as a living organism.
References:
RNA double helix structure identified using synchrotron - McGill University
Double-stranded RNA viruses - Wikipedia
Rotavirus - Wikipedia

dsRNA can also occur in mitochondria, since they have circular genomes, both strands of which get transcribed. This can cause problems if the mitochondrial dsRNAs accumulate and leak out into the cytoplasm, since dsRNA is highly immunogenic: https://www.nature.com/articles/s41586-018-0363-0

Single-stranded RNA (like DNA) can also fold back on itself, creating base-paired helical regions, as in tRNA. It is thought plausible that originally RNA served as both the genetic material and as the structural material before DNA and proteins came about.

As the OP asked for double-helices and did not mention dsRNA, I would like to point out a tool developed by my close colleagues, that predicts secondary structures of RNAs from sequence.
http://rna.tbi.univie.ac.at/cgi-bin/RNAWebSuite/RNAfold.cgi
Here, base-paired regions are assumed to be in helical conformation.
You will see that most RNA sequences have some theoretical potential for auto-base-pairing with small, albeit temporary, helices.
Further, you asked about function of helical RNAs, which I more generally interpret as "structured" RNAs: Important terms or examples that you can further research are: 1."Rybozymes", which are RNAs with enzymatic functions; "Aptamers", which are RNAs found or created by SELEX that can bind biomolecules and even inorganic compounds with high specificity; 3. RNAs that have important functions in "RNA-protein complexes" as found in the ribosome, splicosome, telomerases, nucleases, RNPs and more..


text:
How did shellfish and coral survive acidic oceans in earlier eras?
Throughout most of Earth's history, the planet has had more CO2 in its atmosphere, correct?  Therefore th pH of the oceans was even lower, right?  So how did CaCO3-using animals create their shells back then?

organisms can evolve to cope with more acidic condition albeit slowly, https://cen.acs.org/articles/95/i20/shellfish-adapt-ocean-acidification.html. There are may factors that affect vulnerability which is why some shell building organisms survived.

They didn't survive when carbon dioxide levels in the atmosphere passed certain thresholds in the history and increased ocean acidity significantly; leaving less carbonate for marine life to use for shells or skeletons. For example, up to 96% of marine life (including organisms with CaCO3 skeletons) went extinct in the Earth's most severe known extinction event, Permian–Triassic extinction. Another event called Paleocene–Eocene Thermal Maximum caused a mass extinction of benthic foraminifera.

Five times in the Phanerozoic [the past 542 million years (My)], more than three-fourths of marine animal species have vanished in mass extinctions. Each of these events is associated with a significant change in Earth’s carbon cycle. However, there are a great many disturbances of the carbon cycle  whose imprint in the geologic record is almost exclusively environmental. These other events are relatively benign, with extinction rates barely, if at all rising, above background levels.
Two well-studied examples illustrate these distinctions. The end-Permian extinction [~252 million years ago (Ma)], the most severe mass extinction in the Phanerozoic, plays out over a period of 104 to 105 years; the extinction interval immediately follows a perturbation of the carbon cycle of similar duration. The Paleocene-Eocene Thermal Maximum (~55.5 Ma) is a carbon cycle event of roughly similar time scale, with unambiguous signs of global warming and ocean acidification. It is associated with a significant extinction of benthic foraminifera, but there is no evidence of other major extinctions. What makes these two events so different? The unambiguous co-occurrence of the end-Permian extinction with massive volcanism provides one indication, as does the greater magnitude of the end-Permian carbon isotopic excursion compared to that of the Paleocene-Eocene Thermal Maximum. However, no general distinction, applicable throughout the Phanerozoic, exists.
Thresholds of catastrophe in the Earth system
  By Daniel H. Rothman
  Science Advances | 20 Sep 2017 : E1700906
http://advances.sciencemag.org/content/3/9/e1700906.full
(emphasis mine, removed citation numbers)

Here is an excerpt from a relevant study of Knoll et al. about the affects of end-Permian mass extinction on biomineralization  which includes the extinction percentages of animals that
form skeletons of calcium carbonate and vulnerable to elevated CO2
levels:

Within the marine realm, animals with active circulation and elaborated gills (or lungs) for gas exchange compensate for elevated PCO2 better than organisms that lack these features. Also, animals that normally experience high internal PCO2 , including infauna and metazoans capable of exercise metabolism at high rates, tolerate experimental increases in carbon dioxide differentially well. And among animals that form skeletons of calcium carbonate, species that can exert physiological control over the pH balance of the fluids from which minerals are precipitated fare better than those with
  limited buffering capacity. Based on these features, Knoll et al. (1996) divided the Late Permian marine fauna into two groups, with high and low expected survival, respectively.
As predicted, 81% of genera in the “vulnerable” group disappeared at the boundary, while only 38% of nominated “tolerant” genera became extinct (Figure 6A). The selectivity is even more pronounced when skeletal physiology is considered alone (Figure 6B; Bambach and Knoll, in preparation). Fully 88% of genera disappeared in groups that formed massive carbonate skeletons but had limited capacity to buffer fluids (sponges, cnidarians, bryozoans, calciate brachiopods). In contrast, groups that built skeletons of materials other than calcium carbonate lost only about 10% of their genera. Intermediate taxa—groups like mollusks that have a substantial commitment to carbonate skeletons but some physiological capacity to regulate the chemistry of internal fluids—lost 53% of
  their genera. Of these, those genera considered vulnerable on the basis of the other criteria noted above went extinct at twice the rate of those otherwise considered tolerant.

Biomineralization and Evolutionary History
  By Andrew H. Knoll
  Department of Organismic and Evolutionary Biology
  Harvard University
  Cambridge, Massachusetts, 02138 U.S.A.
https://web.archive.org/web/20100620222809/http://www.geochem.geos.vt.edu/bgep/pubs/Chapter_11_Knoll.pdf
(emphasis mine)

I should point out that some did survive, but it is true they suffered massive losses and die offs.


text:
What is a "Valid Species"?
I read in a reference book on Google Books (Biology of Termites: a Modern Synthesis, eds. Bignell, Roisin, and Lo) that the termite Heterotermes perfidus found on the South Atlantic island of St Helena is a "valid species":

Gay states definitively that "there is no doubt now, however, that H. perfidus is a valid species ..." (p. 537)

I don't understand what "valid species" means.

"Valid" in this case is just emphasizing that the Heterotermes perfidus on this island are a different (real) species, and not just a variation of their closest relatives. You need not get bogged down with how we determine species, or define species. It just means that this taxon (named group) exists as a separate species: a "valid" species, based on differences that some taxonomist deemed important enough to describe and give a name. Others may disagree, and write a paper to synonomize it (sink it into another existing species), but that is part of the messy business of taxonomy.

Many thanks, that is most helpful.

This will vary from discipline to discipline. In paleontology valid species means a population that can be show to be morphologically distinctive in a way that cannot be better explained as sexual dimorphism or a growth distribution. In a living species it may rely on genetic (breeding) isolation.
Basically a "valid" species is meant to show it as distinct from a provisional species or subspecies. Generally the null assumption is that two populations are the same species unless evidence can be presented to show otherwise.The author is saying they have presented such evidence and this really is a distinct species.


text:
I am trying to identify this bone I found on the beach at the Delaware Bay in Delaware. It is 2 1/2 inches wide and 1 1/2 tall

This bone was found at Big Stone beach on the Delaware bay, Delaware. It weighs only 19 grams

Trypophobia warning maybe?

It's a pharyngeal tooth from a large fish like a drum or a parrot fish.

The pharyngeal jaws are for grinding and also contain a pharyngeal mill, where larger and smaller teeth grind coarser and finer coral pieces. Fish like the Black Drum use similar teeth to grind bivalves and molluscs.

They are ideal for scraping and crushing the tough and calcified materials that make up the parrot fish's diet, coral skeletons and polyps, and algae-covered rocks.
The teeth are typically arranged in several rows, with each row containing multiple tooth plates. The outermost row consists of larger, stronger teeth, while the inner rows may contain smaller and more specialized teeth for further grinding and pulverizing food particles. This multi-row arrangement provides parrot fish with an efficient means of food processing. teeth of that kind are also found in other fish, and they are reinforced to handle high mechanical loads. https://www.sciencedirect.com/science/article/abs/pii/S1047847720301039

Thank you for this answer!  mystery solved.


text:
Do sharks fart?
My son is 5 and I'm encouraging him to be curious and ask questions of the world around him.
He asked if sharks fart and how does it smell?  He feels that it would smell of fish and be disgusting.
He was also asking how anyone would know or be able to check. I don't know the answers and am teaching him how to research.

Nice first question, welcome! What have you tried to asnwer that question?

https://www.thenakedscientists.com/articles/questions/do-fish-fart

Thank you very much, had much hilarity explaining the answer    he is particularly  taken by thr idea of herfing communicating by farting!

@Cameron Well done for encouraging your son. If I were you, I'd try to get him to think about how we sense the qualities that constitute a fart and what mechanisms create the fart. A fish may well fart but will we hear it? Will we smell it through the water? Linking back to the creation of the fart (production of gases in the intestinal tract), would we see a new effect like a bubbling in the water?

I thought that anaerobic decomposition will definitely cause methane in any animal which has an intestine. Why isn't that so for all species?

Excellent question. Via Southern Fried Science: According to Daniella Rabaiotti, a postdoctoral researcher at the Zoological Society of London, sand tiger sharks are the only shark known to fart.
They gulp in air at the surface, store it, and when at depth let the air our in the form of a fart to alter their buoyancy. Air lets them float instead of sink, so when they want to sink, that's when they release the air. Shark fart source
There is also a book of species known to fart, confirmed by scientists.
Book of farting animals on Amazon


text:
What type of shell is this?(Answered)
This is Calcareus tube worm and Was found and Located on Culebra Island, Puerto Rico
Picture 1: A up close image of the shell
Picture 2: a view of the top part of the shell showing the shells coloring.
Credits for the answer: @Jiminy Cricket
Website Credits:
https://gohiking.ca/animals/fish/marine-worms/calcareous-tube-worm/

given that they are both calcium carbonate, as soon as the coral started growing on it, the fusion process would have started.

perhaps it's a parchment tube or a keel worm. https://www.beachstuff.uk/marine_worms.html

Could you try to make some pictures with a scale? It would be helpful to see a bit more of it. To secure it in place you could place it on some plasticine, than you don´t have to hold it and the hand isn´t the star of the picture.

It's a Tube Worm.

Calcareous Tube Worm, Vancouver Island, BC, Photo By Bud Logan
From Gohiking.ca.
They anchor themselves to rocks, or animal shells, poking out their filter-feeding aparatus which draws small invertebrates and algae into the mouth. As they grow they deposit a calcerous tube around their bodies for shelter from abraisive silt-carrying currents
and protection.
They're seen in a variety of sizes and shapes in marine habitats, from squiggles on rocks to large, straight stands, much like a small forest.
Giant Tube Worms: (Courtessy of Seasky.org)

NOAA, public domain.


text:
CRISPR/Cas9 edited E.coli on AFM?
I am doing CRISPR/Cas9 experiment on E. coli. I am introducing recombinant plasmid  BPK764 (which carries Cas9 + sgRNA designed and added later in that plasmid) into compentent E.coli cells which already carries another plasmid with GFP gene. sgRNA will be designed so that it corresponds to that GFP gene becouse my main point is to cut out GFP gene. The main result of this experiment will be E.coli cells that do/don't express GFP gene (depending on CRISPR/Cas9 efficacy), therefore, the resultant cells will or hoply won't light green. I will see that under UV lamp, and by fluorescent microscopy.
Now I'm getting to my question.
Is there something on those resultant cells (some trait, like membrane structure, youngs modulus, that differs from CRISPR untreated cells) that can be visualized on AFM (atomic force microscopy)? Something that changes on cells after inserting plasmid that can confirm efficacy of this experiment?
Or maybe some other idea on this experiment using AFM?

Welcome to Biology.SE, Mila99. I think there is a good question here, but it's not entirely clear. Are you asking for a suggestion for a control that you can use to evaluate whether the plasmid has been successfully incorporated? Does it need to involve AFM?

Unless you're specifically targeting genes involved in the physical morphology of the cell, I doubt you would find any differences with CRISPRed vs non-CRISPRed cells that is measurable via AFM.
Perhaps you should instead target genes known to contribute to the structure of the cell wall, which I would expect to be the dominant material contributing to the Young's modulus. Since you mentioned GFP as a tool for selecting for "successful" cuts, it might be worthwhile looking into generating a multiplex plasmid that allows you to target several loci with a single construct. Such kits are available on Addgene and contain associated publications and manuals on how they can be used.
So to summarize, no, I don't think there is anything physically different about cells that have been CRISPR treated compared to a control group. If you did want to use CRISPR to effect a knockout of the fluorescence in the competent cells you described and alter the cell mechanics, you would likely have to generate a multiplex CRISPR plasmid with multiple gRNA cassettes for both GFP and perhaps some gene involved in cell wall formation. Keep in mind that your efficiency percentage is compounded with each new target in the same multiplex – instead of a single cut being deemed successful, you will have raised the bar to 2 cuts being deemed successful without doing anything to improve the efficiency of a single cutting event.
Hope this helps, and I'd be happy to discuss this more.


text:
What's the smallest flier that migrates?
Painted ladies and monarchs migrate hundreds of miles (~1.61 hundreds of kms).
Are there long distance fliers that are significantly smaller?
Dual question: Are fliers' migration distances strictly a function of size? Or are there any fly-sized 1000-mile migrators?

The marmalade hoverfly (Episyrphus balteatus) flies to Southern Europe and back every year.

It's difficult to track and find them compared to birds and butterflies, here is a study witch citations: https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1570-7458.2007.00568.x?purchase_referrer=scholar.google.fr&tracking_action=preview_click&r3_referer=wol&show_checkout=1
it is now known that large numbers of E. balteatus migrate South during the autumn period. Therefore, it has been sug-gested that a comparable migration to the North helps tore-establish E. balteatus populations in northern Europe during the spring. There are many records to show that some hoverfly adults are active so early in the spring that they could not possibly be long-distance migrants. Nevertheless, although some adults remain active late into the autumn, few authors have managed to find females in overwintering sites
studies have suggested that E. balteatus migrates in large numbers during late summer and autumn to the Mediterranean area and only return to central and northern Europe during the following year(Aubert et al., 1976; Gatter & Schmid, 1990; Kehlmaier & Martínez de Murguía, 2004; Hondelmann et al., 2005).
https://www.sciencenews.org/article/flying-insects-tell-tales-long-distance-migrations

That's pretty small! How long do they live? Vanessa's take 6-ish generations to make the Africa-Europe-Africa trip each year.

Hi @user38715! According to the Science News article in com.prehensible's great answer, they only live for about a month! They accomplish a tremendous amount in a short period of time, and they're gorgeous too!


text:
Do birds grieve and feel emotion?
Crows are surprisingly clever with tool making/use and even understanding displacement water over sand! Clearly there's some relatively high level cognitive processes going on up in those avian brains.
When I stumbled across a video of what appears to be a bird grieving over its mate (shown in clip below), I wondered how far animal emotion and psychology goes.

Is that bird in the video grieving? (and shaking because of stress?)
What species of bird is this?

note birds do grieve, this is just not an example of it. https://psycnet.apa.org/record/1993-98443-000

@John: How is it possible to know?  It's certainly possible for humans to grieve without displaying outward signs, or to counterfeit what we see as signs of grief while not feeling the actual emotions.

@jamesqf first grief has physiological and neurological signs, it is a defined behavior, second out of the two options that the birds are grieving or they acting like they are grieving on the off chance a researching is looking the former is vastly more likely than the latter.

Your "grieving bird" is a video of a peregrine falcon (Falco peregrinus) and its (nearly?) dead chick on a hot summer day in Phoenix, Arizona (USA) in 2016.

 Photo credit: Arizona Game And Fish Department
The video is from a nest camera webcam set up in the Maricopa County building in Phoenix, Arizona by the Arizona Game and Fish Department. (See this video for more information). The camera was active in 2016, but according to here the falcons did not return to the nest in 2017. Your video shows one of the adult birds with the only chick that hatched (out of 4 eggs) in 2016. That chick died from a combination of heat and an 8-story fall in June 2016 [Source]. Your video is an edited and audio-less version of a video capture of the live stream that can be seen on Youtube. The information for this video indicates that the adult bird in view is the father.
The adult falcon in the video is not whimpering, crying, or grieving. Instead, the bird is trying to cool down on a hot day. He is displaying a familiar temperature regulatory behavior: panting.
From Bartholomew et al. (1968):

Most birds pant when subjected to heat stress...

In fact, in the more complete video I link to above (with audio), you can clearly hear the bird making panting sounds while breathing heavily.
The falcon also spreads out its wings to better help cool himself down toward the end of the video as it cares to its injured chick.
You can see another video of a panting falcon in New Hampshire (USA) here, and you can find more information about panting, gular fluttering, and other thermoregulatory behaviors in birds here, here, and here.

(+1) Far more believable explanation than grieving.

Most animals have some shared reactions to anti-stress drugs and painkillers, for example it has been proven that lobsters react to the same painkillers as humans in response to stimuli.
Birds are much closer and have a lot of shared characteristics with humans, fear, heart rate changes, adrenaline, stress. There are many studies about general stress, for example: https://www.pnas.org/content/early/2017/06/06/1706164114
That doesn't mean that birds form strong bonds with their children. Penguins have been observed to nurse and prod frozen babies to try to revive them. Complex social emotions have not been strongly proven with most animals, mostly primates, dogs, elephants. Parrot owners will tell you that paired parrots often mourn, lose appetite and die, after their partner dies. They also try to defend their babies with agression. So we can't rule out that birds have parasympathetic nervous reactions similar to our own. humans bite their nails, birds pluck their feathers! https://www.thesprucepets.com/do-birds-get-depressed-390405
You should check this TED talk, about animal psychology:
https://www.youtube.com/watch?v=-wkdH_wluhw


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Help with jellyfish species identification
Our research group (Evolutionary Genetics Group, University of Zurich) has received a letter from a special needs child who has kindly asked us to identify three jellyfish species.
Unfortunately, the letter does not include anything else except three rather low quality cutouts from what I assume is a childrens book. Nobody in our lab has any knowledge about jellyfish taxonomy so any help is greatly appreciated.

https://jellywatch.org/

Be warned that these are just best guesses - as you said yourself, these aren't great images for identification as they appear to be simple drawings:
1) this looks a lot like Aurelia aurita - though the lack of any internal patterning in the drawing makes me think perhaps otherwise.

image source: https://www.leisurepro.com/blog/wp-content/uploads/2017/05/shutterstock_272438348.jpg, https://holidays-majorca.co.uk/wp-content/uploads/2017/01/Aurelia-Aurita-S-300x225.jpg
2) possibly a Turritopsis dohrnii or nutricala - if so then this is the 'immortal' jellyfish. shape of bell is correct and the lappets seem reasonably close, it's just the internal structures that I'm not sure about.

image source: https://www.cairnsholidayspecialists.com.au/shared_resources/media/irukandji-jellyfish-in-far-north-18836_400x322.jpg
3) Very unsure about this one, but potentially a Atolla wyvillei? definitely has some visual features in common and I can't find anything else that's similar. I can also see how an artist would derive that image from this species.

Image source: https://www.mindenpictures.com/cache/pcache2/90194947.jpg, https://c8.alamy.com/comp/E45A4H/deepsea-medusa-jellyfish-atolla-manubrium-gulf-of-maine-atlantic-E45A4H.jpg
I hope these at least give a starting point and are of some help, I think the nature of those images will make it hard to get many better answers. Good luck!!

Thank you very much! I did get in touch with Lisa Gershwin via email as well. Species ID I got from her are: 1: Aequorea victoria, 2: Polyorchis penicillatus, 3: Atolla wyvillei. But I think based on the photo quality one cannot be 100% sure. In any case, I'm sure the kid will be excited and I will send him the full list with all species proposed.

Well, I defer to her better judgment! They certainly fit better than my ones... I'm chuffed to bits that I got Atolla wyvillei right though!

-1. Looks like your 1st 2 are wrong. Good job on the third. (You can [edit] if you think you can improve your answer)


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Can someone identify this plant I saw in NYC (might not be native idk)
I've never seen a plant with these type of leaves before and was wondering if anyone recognized/can figure out the species.

Okay so simple solution I saw the owner of the plant out and just asked what it was. She said it was a Konnyaku Potato (Amorphophallus konjac 'Nightstick'). You can see the branching shoot at the bottom, similar colors, and similar leaves.

That looks like it is probably a single leaf coming up from a tuber.
That fact combined with the mottled pattern on the petiole (leaf stalk) and the shape and branching pattern of the leaflets makes me guess it was something in the genus Amorphophallus.
Example image:
Other images for the "voodoo lily".

please provide some evidence for why you think this is the case as well as a picture if you can find one in the public domain to share. I think you're correct, but your answer is not so great if your links die. We typically want the answers to provide more stand-alone evidence than yurs currently does, especially for [tag:species-identification] questions (in which many people provide incorrect IDs). Please [edit] to add this additional detail. thanks!

@forestecologist: Finally figured out how to insert an image — is this better?

Better, yes, But if you could provide a bit more detail (e.g.,what about the petiole is significant?, etc.) and a source supporting claims that X about the petiole (or mottled leaves, etc.) are in fact indicative of this group, your answer would be better still. Adding these types of details & references does 3 things: 1) allows you to double check yourself (especially if you haven't seen formal sources yourself), 2) provides a reader greater confidence  you're right, and 3) enables readers to easily find a (hopefully) good gateway to learning more. In other words, The extra work pays off

Thanks for the help, the actual plant was in fact of the amorphophallus genus so props on that. I'm sure we could've figured it out with some research into the genus you provided had a more direct opportunity for answers not presented itself.


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How is C4 pathway more water efficient than C3 pathway in photosynthesis?
In the C3 pathway:

1 H2O molecule is required for the fixation of 1 CO2 molecule.
In the C4 pathway:

The only H2O molecule used is in the calvin cycle, so 1 H2O molecule required for fixation of 1 CO2 again.
So, how is C4 pathway more water efficient? I tried looking up more detailed diagrams, but I couldn't find one which gave any different (H2O consumed) to (CO2 fixed) ratio. Any help is appreciated.

Actually, water is used in the light-dependent portion of photosynthesis, not the Calvin cycle.
The added water efficiency doesn't actually relate to water's involvement in chemical processes of photosynthesis at all. Water is instead lost incidentally through stomata when they're opened to allow CO2 into the leaves (see here for explanation). This CO2 IS required for the light-independent Calvin cycle.
Both C4 and CAM plants preserve water by decoupling (in space or time) C-fixation from the rest of the Calvin cycle (see here). They instead "store" carbon in 4-carbon molecules to use as a C source in the absence of CO2 (i.e., when stomata are closed). In doing so, they can perform the Calvin cycle without receiving more CO2. As a result, C4 and CAM plants can photosynthesize without having their stomata open all the time (or during the heat of days for CAM plants). The final result: less water lost through evaporation out of the stomata


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What is this hairy, striped orange-black caterpillar?
There are so many these hairy, striped orange-black caterpillars in my backyard.

What are these caterpillars? Are these dangerous?

Welcome to Biology.SE! For identification questions please: 1) upload an appropriately sized image (free tools for image resizing exist — e.g. https://picresize.com/), 2) include the location (e.g. country and region — the more specific the better), and 3) include habitat information (e.g. type of plant community and species the caterpillar was found on). ——— The location and habitat can be essential clues for identification and links are discouraged since 1) if they can break they render this post and any answers worthless, and 2) they can be used to link to malicious websites.  Thanks!

Resembles Lophocampa maculata but with orange and black striping reversed (and similar in pattern to Platyprepia virginalis but without the abundant white setae). Also, L. maculata appears to be confined to more northern regions of North America* based on the range information I've seen.  I've seen images of your exact specimen from Costa Rica here.

It's a woolly bear caterpillar which will later grow to become Isabella tiger moth.

Are you sure, it's the same? The color scheme is reversed in the picture..

OP's specimen is possibly Erebidae like the woolly bear, but the woolly bear (Pyrrharctia isabella) doesn't live as far south as I assume the OP's image was taken. Also, as the previous comment pointed out, just look at the color difference between your guess and the OP's picture to realize it is likely incorrect. Please be more careful when answering [tag:species-identification] questions on this site. Also, your answers should provide greater detail and reputable sources to support your claim. See our [help] for advice for writing good answers. Thanks!


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Can anyone please help me identify my house plant?
I know this may be an impossible task, but I am one to hope ! My mum had a house plant which had small, green, oval shaped leaves which naturally grew towards the ground (hanging plant). Once every year the plant would flower for several weeks to several months and would have little white flowers bloom. Inside the white flowers were pink baby flowers (they were tiny) and they looked like they were made of glass ! The plant did not need much maintenance and was easy to keep happy, I live in the UK.
Unfortunately my mum died last year but had given the plants to my nan for safe keeping whilst we moved house and she refused to give them back to us. I was hoping to buy one as a memento to my mum, but I cannot find it anywhere and I have no clue as to its name and I sadly do not have any photos. Can anyone help me at all please ?
Thank you,
Molly x

When you say the leaves were small, what size are you thinking of? Could you please edit your post and add an estimate in cm/inch of the leaves, flowers and the whole plant? And where the leaves rather dark or light green?

Was the white flower star shaped?

a drawing would be better. your nan can just give you an offshoot or a cutting or a photo.


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How fast is the patellar reflex?
I have found a lot of content on the patellar reflex, but I cannot find any studies on how fast the reflex is, from onset of stimulus to innervation of muscles.  Does anyone know of either a study or at least a ballpark number for how fast that reflex is?

Mamizuka et al. (2007) calculated acceleration data of the patellar reflex.
Their study measured the reflex generated in response to the tapping force applied to the patellar tendon with a customized tendon hammer. They measured using a tri-axial accelerometer placed at the ankle joint.
They found:

the time delay (29.6+/-6.0 ms) and the acceleration time (150.8+/-19.5 ms) of the speed response were quite constant for all participants.

Mamizuka, N., Sakane, M., Kaneoka, K., Hori, N. and Ochiai, N., 2007. Kinematic quantitation of the patellar tendon reflex using a tri-axial accelerometer. Journal of Biomechanics, 40(9): 2107-2111


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What is vascular cambium?
I'm confused over the two terms vascular cambium and intrafascicular cambium.
Is vascular cambium the same as intrafascicular cambium?

Intrafascicular and vascular cambium is the same.Intrafascicular is primary meristem but interfascicular is secondary as it developed from pith ray.

I know nothing about plant physiology but I googled your question and here is what I found
Vascular cambium
From wiki

The vascular cambium (plural cambia) is a plant tissue located between the xylem and the phloem in the stem and root of a vascular plant, and is the source of both the secondary xylem growth (inwards, towards the pith material at the center of plant, often dead and/or deteriorated, that is composed of parenchyma tissue) and the secondary phloem growth (outwards [to the bark, rough or smooth, of the plant]). It is a cylinder of unspecialized meristem cells that divide to give new cells which then specialize to form secondary vascular tissues.

Intra fascicular cambium
From Biology.easlife

The cambial strip which is present between the primary xylem and primary phloem is known as the intra fascicular cambium. The intra fascicular cambium is also known as the vascular cambium. During the secondary growth the cambial ring is formed by the inter connection of the intra fascicular and inter fascicular cambium. - See more at: http://www.biology.lifeeasy.org/5040/what-is-intrafascicular-cambium#sthash.aY3SPblI.dpuf

What is the difference between fascicular cambium and inter fascicular cambium?
From biology.lifeeasy

The cambium present within the vascular bundle is called intra fascicular cambium or vascular cambium. It is present between the primary xylem and primary phloem. The intra fascicular cambium is primary in origin.
The new strip of cambium which is formed from the permanent cells of inter fascicular parenchyma is called the inter fascicular cambium.  The inter fascicular cambium is secondary in origin since it is derived from the permanent cells of medullary rays.

Need more?
If the above definitions don't help, you should include in your question why these definitions don't help and what is unclear.

The Vascular cambium is responsible for secondary growth, which is growth in thickness. Whereas, primary is growth in length. Once, the length-wise growth of the xylem and phloem are accomplished, growth in thickness or growth inwards through the vascular cambium occurs; it occurs in wood-based plants.

This doesn't address the question of intrafascicular cambium.

Vascular cambium is made of two parts. one is interfascicular vascular cambium and other is intra fascicular vascular cambium. The part between xylem and phloem is called intra fascicular vascular cambium.


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Why does mouldy food make you sick?
Bread gets mouldy pretty quickly. My parents (both of whom are nurses) throw out a loaf of bread after a spot of mould is seen (because "if you can see one spot, it means the whole thing is covered in mould spores") because they say you'll get sick if you eat it. The USDA also has a handy chart on it's mould page telling you when you should discard food with mould on it.
Is it the mould itself that makes us sick or is it something that the mould is releasing?
What are the mechanisms that cause us to feel sick after eating mouldy food?
The USDA says that there can also be bacteria along with the mould on the the food - is this what is really making us feel ill?

Depends on the kind of mould. There is a story that an entire French village died because of ergot infested bread. They died of exhaustion.

One of the most common toxins in mouldy food/bread is aflatoxin.
The exposure to high amount of aflatoxin can lead to acute aflatoxicosis with fulminant hepatic failure and even death.
While mild exposure to aflatoxin could be asymptomatic, it is better not to take a chance considering possible complications (citation from the link above):

Aflatoxins produce acute necrosis, cirrhosis, and carcinoma of the
  liver in a number of animal species; no animal species is resistant to
  the acute toxic effects of aflatoxins; hence it is logical to assume
  that humans may be similarly affected. A wide variation in LD50 values
  has been obtained in animal species tested with single doses of
  aflatoxins. For most species, the LD50 value ranges from 0.5 to 10
  mg/kg body weight. Animal species respond differently in their
  susceptibility to the chronic and acute toxicity of aflatoxins. The
  toxicity can be influenced by environmental factors, exposure level,
  and duration of exposure, age, health, and nutritional status of diet.
  Aflatoxin B1 is a very potent carcinogen in many species, including
  nonhuman primates, birds, fish, and rodents. In each species, the
  liver is the primary target organ of acute injury. Metabolism plays a
  major role in determining the toxicity of aflatoxin B1; studies show
  that this aflatoxion requires metabolic activation to exert its
  carcinogenic effect, and these effects can be modified by induction or
  inhibition of the mixed function oxidase system.

Here's a bit of additional information (Although there's an answer from Ilan that satisfied you.)

Is it the mould itself that makes us sick or is it something that the
mould is releasing?
What are the mechanisms that cause us to feel sick after eating mouldy
food?
The USDA says that there can also be bacteria along with the mould on
the the food - is this what is really making us feel ill?

There are two things to consider.

Food infection : bacteria or other microbes that infect the body after consumption
Food intoxication : ingestion of toxins contained within the food (includes modls), including bacterial produced exotoxins

Majority of food poisoning is caused by bacteria, viruses, and parasites rather than toxic substances in the food. e.g. Staphylococcus aureas, salmonella, Bacillus cereus, three common types of bacteria that can lead to food poisoning.
Molds are neither plant or an animal. They are microscopic fungi. Some food molds produce toxins that cause allergic reactions and respiratory problems. And a few molds in the right conditions, around the Mycelleum,  Mycotoxins are produced; poisonous substances that can make you ill. Mycotoxins also tend to affect more biological systems in our body than do pesticides or heavy metals, partly because fungi have the ability to dodge our immune system by rapidly mutating, while at the same time producing chemicals that suppress our immune system. (You will find more information Mycotoxins here.)
Mycotoxins as a group cannot be classified according to their mode of action, toxicology or metabolism. These vary according to the different chemical structures, sensitivity of the species to the toxin and also factors such as sex, age, health and diet. There are a large number of mycotoxins with a great diversity in their mode of action. Additionally, additive and synergistic effects can occur in the presence of two or more mycotoxins. Following there are the most important mycotoxins and their mode of actions, toxicology and metabolism as well as main symptoms and target organs. (This link explains in great detail.)

» Aflatoxins (discussed above by Ilan)
» Trichothecenes
» Ochratoxins
» Fumonisins
» Zearalenone

Ochratoxin A (OTA) is a carcinogenic compound produced by several species of molds, such as Aspergillus and Penicillium, found in a wide range of foods, including cereals, dried fruits, coffee, cocoa products, wine, grape juice, beer, liquorice, blood products, baby foods and spices.

New studies confirm Ochratoxin A inhibits Neurogenesis(the formation of new neurons in the brain). Other than that, its toxicological effects include nephro-
toxicity, nephrocarcinogenicity and immunotoxicity as well.
Aspergillus on Bread - Mold.

The molds that we see on the surface of the food is just a tip of the ice berg. It is an invader, whose roots like threads may have gone deep down entire food (although some says bleu cheese with mold is edible). Growing right along with mold are what are called "gram negative" (e.g. Escherichia coli) and "gram positive" bacteria. Just like mold, they require moisture and organic material to thrive and are often found growing in the same places as mold, and the synergistic action between mold and bacteria further worsen inflammatory health conditions. Oftentimes, those bacterial infections occuring alongside fungal infections make treatment more complicated.

"New studies confirm Ochratoxin A leads to Neurogenesis (inhibits the formation of new neurons in the brain). " - this sentence should be revised as Ochratoxin does not lead to -, but inhibits neurogenesis (the clause and the clarification do not match).

@Ilan, ouch :) thank you I seemed to have made a mistake here. Let me correct it.


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Do Asian koel males communicate through calls?
Male Asian koels are heard making long koo-Ooo s  which are returned by similar koo-Ooo s1 from some far away place. While the female makes short shrills.
I never had the opportunity to see the other bird and find out its sex. But it sounds just like the first one.
Is it actually communicating with a male bird? What is the known reason if so?
1 The reply calls (to be found around 0:29) in the video are really low.
Note:

A singing male bird also gives desperate accelerated calls when  mimicked.
Its breeding season has just begun in India and this communication can be heard.

I'm not sure about this particular species of bird, but males of numerous species call throughout their territory to inform other males of their territory. This is especially true of migratory birds that move in and out of areas (with recently sexually mature males now trying to find their own territories and fighting for limited space) "Responses" could very well be males in nearby territories doing the same thing. Just a thought...

Also, I don't hear any response in the video you link to -- it just sounds like echoes of the male in front of the camera. Are you referring to that sound, or is there another call I missed?

Still working on this question and the following are the findings:

The male bird when mimicked possibility mistakes the mimic as an intruder in its territory and so it gives louder & accelerated calls.

The male while defending its territory gradually approaches its adversary, hopping from twig to twig calling loudly and displaying its threatening posture. ( B S Lamba (1969) )


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Why do endotherms need more food than ectotherms?
I have a rough idea: endotherms need more food to keep their temperature stable whilst ectotherms use less of their food in respiration.

but that's just me parroting the textbook I don't really understand it.

Could someone help out? Thank you.

That's basically right.

Endotherms also called warm blooded animals have the ability to regulate their body temperature by themselves.

If the endotherms are in a cold place their body increases the metabolism and generates more heat. This will compensate for the cold outside.
In a hot region the body metabolism is tuned down (this is not as efficient as the adaptation to cold region - as the metabolism can't be turned down below a certain limit - this will result in death) a little and heat generation is somewhat reduced. The second and more efficient mechanism is the heat dissipation by sweating and through skin (directly).

Ectotherms on the other hand, do not have efficient temperature regulation systems.

In warm regions when the temperature is high, the ectotherms seek shade and low-temperature areas to prevent over-heating
In cool regions they seek sunlight and expose themselves to the sunlight for warmth. For the same reason, they can also search out and stay near fire pits, campfires etc...

So when we calculate the energy demands, the ectotherms need more energy as they regulate their own metabolisms to match the need.
The increase in need for energy in hot condition maybe due to:

The extra-processes that are regulated like sweating, increased peripheral vasodilation - thereby increasing circulatory rate (increased work for heart)
This thermo-regulation inturn affects other processes and systems like electrolyte and water balance, excretory system, endocrine system, thrist, etc...

During the cold season increased metabolism itself is the main cause for increased need for energy.

At least in cold temperature elevated demand of food fulfils the law of conservation of energy. To raise the body core temperature requires energy, which has to be taken from anywhere. Apart from depots of fat or glycogen the premier source of energy is food. Homeothermy also has advantages, however, since homeothermic animals are able to move, hunt etc. in conditions, where poikilothermic animals are massively restricted by torpor or staying at shady places.

An ectotherm is an [cold-blooded] organism which is dependent on external sources of body heat. They do not need to regularly consume food to warm their bodies. As a result, they can subsist on lower metabolic rates and varying internal temperatures (poikilothermy). However, physical activity is restricted to certain hours (night) and or habitats; ectotherms tend to be rapidly exhausted.
An endotherm is an [warm-blooded] organism which is dependent on the interal generation of heat. To maintain consistent temperatures (homeothermy), they must regularly consume food for metabolism. This also allows for a greater work capacity than ectotherms. Physical activity is not limited to certain hours and or habitats.

Here's a (hopefully) simple answer:
Ectotherms eat, and convert most of the energy in their food into new biomass (i.e. producing more tissue and growing). Between meals their metabolism (all the reactions in all their cells) slows right down so they don't use much energy.
Endotherms eat, and convert most of the energy in their food into generating heat, converting a small amount into new biomass. So they need to consume more, as generating heat all the time takes loads of energy, even when resting between meals!
Hope that helps, along with the previous answers.

Ben - can you add some links to your answer or other references so others who are less familiar follow your answer? It would help strengthen your answer significantly - thanks for your contributions.


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What is this strange horned, slug-like coral reef dwelling creature?
On the first episode of BBC's Blue Planet II they visited a coral reef and showed some odd reef-dwelling creatures as part of their establishing shots, but they did not identify the creatures.
What is this odd horned, slug-like creature?
(Sort of like a slug with legs?)

I tried a Google reverse image search and it very 'helpfully' identified it as "Documentary film". So close, yet so far.

Disclaimer:
This question was split off from another question since the original was effectively two questions.

I think the OP might be referring to the black leg like things at the front. These are feeding tentacles according to Wikipedia. The tube legs are the short stubby things along the underside. I ended up here wondering about this too - thanks! Great show :)


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What can give rocket salad (Eruca Sativa) a fish smell?
I bought an 'already washed' plastic tray of rocket salad (arugula, or Eruca Sativa) enclosed in a sealed plastic bag. It has been kept in the refrigerator for four days. When I opened it, some 12 days before the "best before" date,  I noticed a strong smell of fish.
I am a regular consumer of this sort of vegetable, I also have some in my garden, so I know how it smells. Yet, by searching on the net I realized that other people have lamented this fish smell in their pre-washed arugula salads.
I am wondering now where does this fish odor come from? Can it come from the plant itself, or is it a side-effect of industrial washing? What exactly is giving this smell? Bacteria, molds, natural decomposition of the plant's essences, or something else?
(Following my instinct I threw the salad away, but I did taste a few leaves and it did not taste 'bad' or 'foul'. It was just the smell that was off.)

A lot of people report a bad smell/taste from arugula when it gets too big, the leaves are best when they are very young. (I don't mean time since picked, I mean time since sprouted) No idea if this is the same thing you are reporting or anything about your source for arugula.

Note: rocket salad is often not Eruca sativa, but some Diplotaxis, because the later growth quicker. My guest it the the water used: it could contains some algea which gives such smell. Days in plastic is an ideal environment (for the few algae in the original water).

Complete guess - the arugula could contain or be decomposing into amine-containing compounds (known to have a fishy smell).
https://en.wikipedia.org/wiki/Amine#Physical_properties

Not a bad guess if you ask me, considering the seeds contain amino acid