text:
E. Coli growth inhibited in Powdered Honey
I ran into problem with my method validation since the E. Coli that I've spiked into my Honey Powder sample can't grow in the media. The media I've used is Merck CCA (Chromogenic Coliform Agar). I've also used the MPN method (3 tubes) using LST Broth with the same result.
Really appreciate if someone Can  lead me into why would this happen and give any suggestion on how to troubleshoot this?
Regards.

If I understood correctly you want to grow E. coli in the presence of honey, right?
This migth be the problem as honey inhibits bacterial grow. See here. Therefore, it also doesn't matter which medium you are using.


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What is the name of the species of this butterfly?
Well,I am from India and live in the northern part of the country.I commonly find these butterflies during winter or spring seasons.

The original image shot is:

Welcome to the site! What size is it?

I'm not an expert, but it looks like a male "common mormon" or Papilio polytes romulus

https://species.wikimedia.org/wiki/Papilio_polytes_romulus

The image of the species on the left looks quite identical and accurate.And also,it’s written on Wikipedia that the species is found in Nepal which is the country lying just above the border our state.Thanks.

Those two butterflies are the same species.  The one on the left is a male.  The one on the right is the female.

source: Stack Exchange

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

sort: votes


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Identifying a mysterious bird in the writings of Hebrew prophet Jeremiah
In Jeremiah 17:11, the verse states:

קֹרֵ֤א דָגַר֙ וְלֹ֣א יָלָ֔ד עֹ֥שֶׂה עֹ֖שֶׁר וְלֹ֣א בְמִשְׁפָּ֑ט
  בַּחֲצִ֤י ימו [יָמָיו֙] יַעַזְבֶ֔נּוּ וּבְאַחֲרִית֖וֹ יִהְיֶ֥ה נָבָֽל׃
Like a 'korei' hatching what she did not lay, So is one who amasses
  wealth by unjust means; In the middle of his life it will leave him,
  And in the end he will be proved a fool.

I am trying to identify the mysterious 'korei'.
Various commentators, including Rabbi Shlomo Yitzchaki, Rabbi Meir Leibush ben Yehiel Michel Wisser and Rabbi David Kimhi all indicate that this is a species that has a habit of hatching eggs that are not its own.
Rabbi Meir Leibush identifies it as a "perniz" but it is unclear to me what language he is using.
Rabbi Shlomo Yitzchaki identifies it as a "cuckoo glontzant" - but he obviously cannot be referring to a regular cuckoo because cuckoos are brood parasites or obligate parasites, but do not bother sitting on other birds eggs.
Are there any birds known to science today with this odd habit?
Are there any birds with latin names (or names in any other language) that correlate to those provided by Rabbi Meir Leibush or Rabbi Shlomo Yitzchaki?

This may be a better for https://judaism.stackexchange.com.

The specific bird doesn't seem to be at all important to the passage; it seems most likely to be referring to a bird that has been a victim of a cuckoo: it's the other bird that is sitting on cuckoo's egg. I think this is not really a biology-relevant question because there is nothing in this passage that would allow a biologist (as opposed to a Hebrew scholar or perhaps linguist) to answer it.

Also in your link on sefaria the translation says "partridge" - doesn't that seem like a reasonable translation?

this page adds to your discussion. However, I agree w/ Bryan, that ultimately this is not a biological question -- understanding the passage likely doesn't rely on a specific species. If you're strictly interested in the biology of the bird, then see my answer, as it should give you some initial info. To ID to specific species, however, cannot be done without further details about the bird. Just answering based on the name is really more of a translation question, not one about bio

I'd also ask whether the passage applies to wild birds (where it doesn't seem to make a lot of practical sense), or the practice of farmers having one kind of bird hatch out eggs of other species,  e.g. chickens hatching duck eggs/

The korei must be a victim of a brood parasite.  It likely refers to a then-current story or common reputation of some such bird (perhaps a domesticated bird as jamesqf suggests).

L.B., thanks for your suggestion, I posted here because I was looking for a specific biological species. Thanks Bryan Krause for your comments, yes, it is likely to be referring to the victim of a cuckoo - but the commentaries I quoted seem to name a specific species, so I wondered if it was known to science. I wouldn't place much faith in the "partridge" translation, these can be arbitrary or mistaken unless sources have been quoted. Does the partridge have the habit of sitting on other bird's eggs? I supposed that if it did, someone would identify it as such anyway.

jamesqf, very interesting point, however, commentaries across the board clearly present it as a habit of the species.

Cowbirds lay their eggs in other bird nests to have the other birds rear their young.
According Cornell's All About Birds informational page on the brown-headed cowbird:

Over 140 host species of the Brown-headed Cowbird have been described, from birds as small as kinglets to as large as meadowlarks. Common hosts include the Yellow Warbler, Song and Chipping sparrows, Red-eyed Vireo, Eastern and Spotted towhees, and Red-winged Blackbird

So, to answer your question, there are many birds that will do this.
More generally, birds such as the cowbird that rely on others to raise their young are considered to be brood parasites.

Sometimes this involves intentional egg mimicry and sometimes it's not so secretive.

There are countless numbers of brood parasites and even more species that act as their "hosts." Your bird could be any number of them.
According to Wikipedia:

The subfamily Cuculinae are the brood-parasitic cuckoos of the Old World

So perhaps their host species would be a good place to start looking...
For example, a quick Wikipedia search reveals that the common cuckoo is one such member of the Cuculinae, and they have more than 100 host species:

More than 100 host species have been recorded: meadow pipit, dunnock and Eurasian reed warbler are the most common hosts in northern Europe; garden warbler, meadow pipit, pied wagtail and European robin in central Europe; brambling and common redstart in Finland; and great reed warbler in Hungary

Thanks for this. According to the helpful link in your comment above, Maimonides writes "The korei is called alhajel (in Arabic...), and in this species the males hatch the eggs just like the females." - another clue. And the "perniz" that I mentioned from Rabbi Meir Leibush is the latin "perdrix" which indeed is the partridge family. Sefaria seems to be on the mark - this source identifies the korei as a sand partridge or a rock partridge. Biologists, does that fit in with what you know of the species?

Trying to be biologically relevant: to the best of my knowledge there are no birds that exists that deliberately want to incubate the eggs of other birds. From an evolutionary perspective, raising offspring is costly. However, like you mentioned there are birds that can act as brood parasites such as cuckoos, some duck species etc. The brood parasites then invest their time on other activities such as foraging and producing further offspring.

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Does anybody knows name of this bird I found in my backyard in India?

I found this bird in my backyard in India. I checked several websites but wasn't able to identify it. Any help would be appreciated.

Open images.google.com drag and drop this image. It will says the answer

I am pretty sure that this is a  Indian Paradise-flycatcher (Terpsiphone paradisi). Since we cannot see the length of the tail feathers, we cannot distinguish between male and female, the later have a much shorter tail.
See the image (from here) for comparision:

More information can also be found here and here.


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How do biologists discover information from fossils?
I have a query about the study of fossils (palaeontology). Let me know about the study of fossils. How do biologist discover "DNA" information from dead and old fossils such as a dinosaur?  (answer this question in a paragraph or two)

Your question appears very broad; you can find entire books/reviews dedicated to this topic. Please narrow your question down and add sufficient details such that it is restricted to a specific issue and can be answered in a few paragraphs.

You can give me selected knowledge

This sounds like a homework question...Please review our homework policy. We ask that all question posters here attempt to search for an answer to their own question & explicitly indicate the research they've done, what they learned, and what is still confusing 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!

@cell0 FYI, I rejected your proposed edit because it makes small style and grammar edits to a generally poor closed question, bumping it and adding it to the reopen queue without any improvement in substance.

How biologist discover "DNA" informations from dead and oldest fossils
  such as dinosaur.

They don't. In general fossils contain very little organic material. It's all been replaced by stone (silicates). On top of that DNA degrades over time.
There have been a handful of cases where researchers have claimed to recover small fragments of DNA from dinosaur fossils, but these are disputed, and are generally thought to be the result of contamination with human or other modern DNA.
DNA has been recovered from some more recent fossils like Neanderthal. For such a general question a better starting place would be to read the Wikipedia article on Ancient DNA.


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Red and yellow insect found in kitchen in Conrad, Montana (USA)
Beetle found in our kitchen in Conrad, Montana (USA) on 3/13/19:

This appears to be a stink bug in the superfamily Pentatomoidea of the true bugs (i.e., order Hemiptera).
Specifically, your specimen appears to be Perillus bioculatus or the two-spotted stink bug.

 Photo Credit: Margarethe brummermann (2008)
You can see additional photos including those demonstrating the species's various yellow vs red color morphs here.
According to the Integrated Plant Protection Center at Oregon State University [my emphasis and links]:

Mature nymphs of the two spotted stink bug are about 8 to 9 mm long. Adults range in length from 10 to 12 mm. Nymphs may [be] pale yellow or reddishorange with a distinct black "Y-shaped" marking on the pronotum and two black spots on the thorax.

According to Wikipedia, this species is usually a beneficial predator (especially of the Colorado potato beetle), but early nymph stages feed by sucking on potato stems. The trade-off, I would guess, is worth it.

In fact, the color variation in this species (namely the shift from white/yellow to red) that my earlier link shows photos of is a result of a higher diet of potato beetles. [Source, taken from p 99 in McPherson's 1992 book The Pentatomoidea (Hemiptera) of Northeastern North America].

 Source: bugguide.net
Their range, according to bugguide.net is southern Canada, the U.S. and into Mexico.

I was gobbling cherries one day and I ate a cherry with a stink bug which defended itself on my tongue. It was a bit hot and a bit indescribably chemical. wasn't a major worry though, i had forgotten about it after a while. don't eat them :D their defense works you spew them out haha.


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What is the meaning of "within-season variation"?
I am reading a paper about phenology and climate change for my assignment and I found this concept "within-season variation", can someone explain it to me? and how it is related to changes over time?

Could you link to the paper please

"Within-season variation" may be referring to one of two things (depending on the context):

More commonly: the variation of a variable within a given season (i.e., between months or days within that season).

Öst (1999) demonstrates an example of this use (in the context of breeding season).

Less commonly: the variation of a variable between the same season of different (often consecutive) years. Though this would more often be termed "between years". This is as opposed to "between seasons" which would be be between two different seasons of the same year.

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Can Anyone Identify this Tissue?
I am hoping someone can identify the image below

My wife felt a bug bite her and found this in her hair now she's worried that it was a tick.
the photo is at 40X under microscope. I'm guessing it's an arthropod maybe some kind of beetle but I haven't seen anything like this before.

One usually doesn't feel tick bites. To me it looks like some kind of beetle too.


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UK insect identification
15-20mm long.
Brown legs, head, casing/wings (no flight witnessed).
Black body with protruding back part.
Long antennae.
Very fast running speed.
Seemingly keenly aware of surroundings.
Is this some sort of small cockroach?

Hello and welcome to Bio.SE! Take the tour to learn about the site and earn yourself your first badge. Have a nice stay!

The photo is not very clear, the two spikes at the back identify it as a cockroach, a "forest cockroach", probably a "german cockroach", perhaps she is pregnant? I think they prefer slightly warmer, dryer climates than the UK, whereas the UK is mostly home to slower black beetles, elsewhere in europe, you can turn a stone over and there will be 5 forest cockroaches, which are very fast, and actually quite pretty and silvery in their own way.

https://en.wikipedia.org/wiki/German_cockroach

Thank you com.prehensible. In the picture of the German Cockroach with ootheca, the ootheca looks the same shape but different colour as the one I observed. This cockroach was certainly very fast. I saw her in the kitchen in the evening so that also fits what wikipedia has to say.


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What is this underwater creature?
West Bali, about 10 meters deep. Body is roughly 10 cm across.
Does not move.

Is that "does not move " in the timeframe you allowed? Or based on a timeframe of months of continuous observation.

Lack of movement suggests it's not a sea slug. Possibly a strange tunicate?

I am convinced this is a nudibranch. The features that indicate this are the rhinophores (antennae-like sensory structures at the "peaks"), the cerata or brachial plume (hard to tell which based on this photo, but these are translucent extensions just visible in the "valley" between the two "peaks", if you zoom in). A look here and here shows there is a huge diversity in morphology, but many nudibranchs have some form of these structures. Also, the shape of margins around the edge of the animal matches that of many nudibranch species. These are mobile animals but it is possible it just was not moving during your observation.

I would say that it is a sea hare of some type based upon its appearance and location above course sand. While it was not moving, that could just be a factor of when it was observed. I wouldn't expect a tunicate to have this appearance or be affixed to sandy sediment.

Welcome to Biology.SE. You are more likely to get a positive response to this answer if you explain why your identification is correct. Specifically, please [edit] your answer to add discussion of key features that led you to this conclusion and supporting references or at least validated images. Without this your answer is indistinguishable from opinion and is thus inappropriate for this site. ——— You may also wish to take the [tour] and then consult the [help] pages for additional advice on [Answer] and [Ask] effectively on this site.


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What is a catalytic domain?
I have to answer a few questions from an article I'm reading, and I am just really confused on defining "catalytic domain." I have to relate it to the antibiotic Teixobactin. Is catalytic domain the same as the enzyme's active site?

The catalytic domain is roughly referring to the same part of the protein as an active site and may be used interchangeably in some circumstances:
See here, where "catalytic domain" redirects to "active site."
There is, however, a difference:
From a free online medical dictionary:

active site:
  the place on the surface of an enzyme where its catalytic action occurs.

From Wikipedia:

catalytic domain: structurally conserved (tertiary) structure containing the catalytic function of the protein.

To further clarify: the catalytic domain is the 3D structural independent folding unit of the protein that contains an active site, while the active site (aka "catalytic site) is the area located within the catalytic domain where substrate molecules bind and undergo a chemical reaction.

More precisely, the 'catalytic domain' is the domain of the protein that contains the active site. Of course, there are different definitions of the word 'domain', but a simple one might be an independent folding unit of the protein.

@gilleain very true. I will update my answer.

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What mammal or creature dropped this? (Warning: Gross Pictures)
I'm at a loss to explain what creature dropped or created this. This giant pile showed up virtually overnight.  If someone could point me in the right direction, I'd greatly appreciate it.
The geographical area is Sparks, Nevada.

Probably a bird, or more likely a group of birds.

I know piles of poop like the one sown in your picture from swallows... Barn swallows for example. Is there a nest somewhere above?

Yep, looks like it was 2 birds hiding in the roof soffit.  Didn't think there was an opening in the soffit directly above the pile, but I guess there is.  Couldn't get a good look at what kind of bird they were.  They shan't be returning, however.  Thanks for your help!

You can see a similar pile of bird poop seen below a barn swallow nest:

 Source: deepmuckbigrake
Alternatively, if it really did appear overnight, perhaps a pile pf pigeon poop was pushed out of a nesting area in the soffit?

 Source: Scranton Times Tribune
If it's pigeon poop, you might want to be careful.


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If birds are dinosaurs, then are mammals reptiles?
I'm just curious - it seems generally accepted that birds are dinosaurs. If that's the case, then can we call all mammals reptiles? Can we go even further and call humans amphibians? And since single-celled bacteria were the precursor of all life, isn't just anything a bacterium?

You might want to have a look at If dinosaurs could have feathers, would they still be reptiles?.

@GyroGearloose The simple answer is "no". Birds are not dinosaurs, but the descendants of dinosaurs after at least 65 million years of evolution. This distinction is used so that we all know what each other are talking about. I'm voting to close the question because at the minute the question is a mixture of semantics, rhetoric, and reductio ad absurdum; it's subjective.

Why would birds being dinosaurs mean mammals are reptiles??

It has as much logic as saying if carrots are potatoes, are foxes then plants? Carrots aren't potatoes, foxes aren't plants, and even if carrots were potatoes, would that have any bearing on the relationship between foxes and plants?

Then you can as well say we are all amoeba !

The most primitive mammals are platipus and echidnas. Oldest placental are shrews.

Reptile is not a clade - it is a paraphyletic group because it does not contain all descendants (i.e. birds) of a common ancestor. Humans are amniotes like birds and reptiles but while birds and reptiles are sauropsids, mammals are synapsids. Humans are not amphibians either because amphibia is another paraphyletic group which is distinct from amniotes. Possibly some amphibians and amniotes share a common ancestor. Amphibians, sauropsids and synapsids can be grouped together under tetrapoda. So both humans and frogs are tetrapods but humans are not amphibians.
However, birds are dinosaurs and belong to a very specific sub-clade of dinosaurs called theropods. Both dinosauria and theropoda are monophyletic groups - i.e. they contain all the descendants of a common ancestor.

Extending this to bacteria. Yes you would group all living things (eukaryotes and prokaryotes) and can call them cellular living organisms.
However, animals (or any other eukaryotes) are not bacteria (they have diverged a lot). Moreover, extant bacteria are not precursors for all life. The precursor is called Last Universal Common Ancestor but we don't know much about it (at the moment it is a hypothetical organism). Eukaryotic evolution itself is a big mystery. So it would be  preposterous to call all lifeforms as bacteria.

Well Reptilia and Reptiliomorpha are clades (which contain mammals if I am not mistaken).


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What type of wildflower is this?
I live in Utah and I'm wanting to plant some Utah native plants in my backyard. There is this wildflower everywhere in the mountains of Utah and I really want to know the name. It looks like some sort of Paintbrush (Indian, Wyoming) but I've searched for those and they don't look the same.

As picture doesn't have different close up looks, by its color and looks I think, this is definitely a species of Castilleja ,commonly known as Indian Paintbrush or prairie-fire :

Castilleja, commonly known as Indian paintbrush or prairie-fire, is a genus of about 200 species of annual and perennial herbaceous plants native to the west of the Americas from Alaska south to the Andes, northern Asia, and one species as far east as the Kola Peninsula in northwestern Russia. These plants are classified in the family Orobanchaceae (following major rearrangements of the order Lamiales starting around 2001; sources which do not follow these reclassifications may place them in the Scrophulariaceae). They are hemiparasitic on the roots of grasses and forbs. The generic name honors Spanish botanist Domingo Castillejo.

It is more likely to be a species of Castilleja called Castilleja rhexifolia.
Common names : Alpine paintbrush , Rose(y)  paintbrush.
Family : Orobanchaceae (Broomrape Family)
From reference : Comparison between Castilleja haydenii and Castilleja rhexiifolia ;

Castilleja Rhexiifolia bract colours are most often hot rose-pink, but they range from subtle magentas to flaming rose to hot iridescent pink.

And on the left and right sides of the question picture have comparatively lower/light pink colour or iridescent pink color and the central flowers are comparatively darker or more magenta when compared to side ones.
Side ones :

Central flowers /focused flowers :

Welcome to Biology.SE. You are more likely to get a positive response to your answer if you explain why your identification is correct. Specifically, please [edit] your answer to add discussion of key features that led you to this conclusion and supporting references or at least validated images. Without this your answer is indistinguishable from opinion, which is not appropriate for answers on this site. ——— Thank you for taking the the [tour], but please also consult the [help] pages for additional advice on [Answer] effectively on this site.

@tyersome Thanks a lot for the guidance! I have updated my answer.


text:
What is the name of this red and blue striped spider (?) - Brazil, Rio de Janeiro

Anyone knows the name of this thing? I found it in our bathroom. It is maybe 10-15 mm.
It looks like a spider but the colors left me puzzled

Definitely a spider (fused head+thorax, eight legs, jaws) but sheesh those colours :)

This appears to be some species of jumping spider (family Salticidae) in the genus Psecas.
For example, some red/blue striped species of Psecas:
]

 Sources: Top: Alchetron.com (image: Edwards, 2001)  |   Bottom: Tree of Life (image: Maddison 1994)
Wikipedia lists the following species from Brazil:

Psecas chapoda (Peckham & Peckham, 1894) – Brazil
Psecas chrysogrammus (Simon, 1901) – Peru, Brazil
Psecas viridipurpureus (Simon, 1901) – Brazil
Psecas zonatus (Galiano, 1963) – Brazil

Psecas chrysogrammus is my best guess given my limited knowledge of the specimen, this family, and arachnid literature.
We likely can rule out P. viridipurpureus (see here) and P. chapoda (see here) because of the longitudinal striping pattern of the dorsal abdomen of these two species.
I couldn't find any definitive or reputable sources regarding P. zonatus.
The sketch of P. chrysogrammus here seems to indicate that this specific species has the horizontal striping seen in the OP's specimen.
Salticidae.org provides these sources for P. chrysogrammus ID info:

M. E. Galiano 1963b. Las especies americanas de aranas de la familia Salticidae, descriptas por Eugene Simon. Redescripciones basadas en los ejemplares tipicos. Physis, Buenos Aires, 23 (66): 424, t. 32, f 14-18.
Simon E. 1901a. Histoire Naturelle des Araignees. 2(3-4) Paris: 460, f 528, 533(=H).


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What is this insect

This was found in my house in florida

Welcome to Biology.SE. Your question seems fine, but could you add the size of the animal (and maybe give a somewhat more precise title to your question - e.g. What is this x cm winged insect found in Florida, US?), please? That makes it more likely for you to get an answer.

That is a Milkweed Assasin Bug, Zelus longipes. Order Hemiptera, family Reduviidae. Here is a good website that describes a lot about them. http://entnemdept.ufl.edu/creatures/beneficial/bugs/zelus_longipes.htm


text:
What kind of spider is this from New Zealand?
This is biggest one I have caught so far:

They would occasionally walk into my house and wait for the night to go out and about.

The features are fairly generic. It is probably a house spider, genus Badumna

Please let it go free. It shares this living space with you!!

Spiders are much more likely to be highly beneficial to you than to be harmful. Please consider leaving them alone, or if you can't, catch and release.

With the limited info and only a side image (top/bottom photos more helpful for ID), it's hard to pinpoint a specific species. To complicate matters, Manaaki Whenua Landcare research suggests:

Over 90% of New Zealand spiders are endemic, the rest are natural introductions through windborne or human activities. The species we frequently see around are houses and gardens are usually introduced species. Most of the endemic species are restricted to native habitats, from forest to alpine regions

One possible group are the sheetweb spiders (family Stiphidiidae).
According to Wikipedia, most species are speckled brown with long legs with a body length < 2.5 cm and leg-span < 15 cm. This family of spiders is nocturnal, and they can be found in gardens or (ales) even enter homes.
Here's an example specimen from this family:

 Source: Manaaki Whenua Landcare research
According to Arachne.org.au, the Stiphidion genus is the most commonly seen group from this family.

Their image of a female Stiphidion, also closely resembles yours:

 Credit: Dr Greg Anderson, Source: Arachne.org.au


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What is this sand covered insect?
I have found in a wooden house, in the mountains of central Spain this very curious insect:

I was wondering if that was its skin or whether it's decomposition or sand or saw-dust.  That particular region of Spain does have stink-bugs ... but this one doesn't look like anything I've seen before.  A google image search returns mostly arachnids ... but it seems to have only 6 legs.

Possible duplicate of Identifying an insect looking like a crumle

@fileunderwater - Wow, good catch!

The insect in the related question looks quite different. Is it maybe a different species of Masked Hunter? Or at a different age? (When compared side by side, http://imgur.com/a/ovpRW, and given they were in different countries, I'm not sure if I would have recognized it)

@fileunderwater I see what you mean, but the format of anongoodnurse's answer is better than the accepted and upvoted answer on the prior question. If the questions can be moderator merged so that this answer appears on the other, then I would agree with the close, otherwise I think it should stay open. Also it is a bit difficult to identify by search if you don't know where to start.

It's a kind of assassin bug, specifically a Masked Hunter:

The surface of an immature Masked Hunter is sticky and it attracts lint and dust which helps to camouflage this predator.

and

The name refers to the fact that its nymph camouflages itself with dust.

Though they feed on small insects, they will bite defensively, and when they do, it's fairly painful.

I recognize it as a species of "wheel-bug" or, as others have noted, a species of assassin-bug. (I don't know the specific species, though; sorry.)
These predators have a vicious "bite" using hypodermic mouth-parts, and some routinely inject a type of enzyme in the "venom/saliva" that causes great burning or pain; the compound is intended to help the creature suck the internal organs out of "prey" creatures. Depending on the species' size, these may even kill and consume young frogs and toads.
As noted by others, the younger ones stick soil, plant-matter and other material to their exoskeleton as camouflage. This is because, in part, they are cannibalistic; parents and elders have no compunctions about eating their smaller offspring. Of course; if the youngsters get a chance, they will dine on their parents or elders, too.
Aside from some wasps that lay eggs on the paralyzed bodies of spiders, these insects are one of a very limited number of species that will often actively hunt down and prey on spiders.


text:
What animal is this? A bee? red mason bee? (Bee-like with brown/orange fur)
The picture was taken at the Bodensee (Lake Constance) in Southwestern Germany in June 2019. I tried to Google "Bee with brown fur", but the only thing that came up was a red mason bee, and the resulting pictures didn't look quite like this photo
Since I was sent the photo, I don't know the actual size of the insect.

Definitely a bee, I'd guess from the family apidae. Do you have other photos? Getting a good ID will probably require a sharper photo.


text:
Larva in cat's water dish
Can anyone help me identify this tiny larva I found in my cat's water dish and tell me how it got there?

It is not likely that identity can be obtained from a larval stage photo only, so you do need to provide more information. Can you provide its size and where you are located? Possibly an insect specialist might have an idea. It is not possible to tell you how it got there.

This is the larva of a moth fly (family Psychodidae: I don't see any legs, there is a well-developed head capsule, and the body segments each have two or three dorsal plates); going further than that requires knowing where you are, and whether or not the Psychodid fauna of that area is well-known as larvae (in practice, this means "forget going deeper" if not located in western Europe).  Larvae of the subfamily Psychodinae (which this is) are aquatic or semiaquatic, which means that a week or so ago an adult laid one or more eggs where you eventually found the larva.

This appears to be the larva of a drain fly (aka moth fly; family Psychodidae).

 Top left is larva; Source: YourWildlife.org; Credit: Matt Bertone
You can use a dichotimous key to help you ID to family. For example, from Bouchard et al. (2004)+:

Body cyclindrical; non-leathery integument...
Head capsule fully visible and completely separated from thorax
Prolegs absent
Thoracic segments not fused or swollen
Abdomen non ending in long respiratory tube
Body segments with 2-3 secondary divisions (annuli); body grey or brown

You can use Arthur Frost's comment to help ID to lower taxonomic levels.
How it got there:
From Orkin:

These pests are particularly likely to be found in bathrooms and kitchens, typically getting into homes through:

Basements
Drains
Windows

 +  Bouchard, R.W., Ferrington, L.C. and Karius, M.L., 2004. Guide to aquatic invertebrates of the Upper Midwest. (Chapoter 13: "Diptera")


text:
What kind of NW USA insect Is this?

What kind of insect is this? I saw it outdoors.

Looks like a nymph of some sort, the wings aren't developed yet.

This is a leafhopper nymph (order Hemiptera, family Cicadellidae); going deeper than that will depend on whether or not the species seen here has been reared.


text:
Can you help me identifying an insect I saw?
I'm a student of biology and yesterday we went to the fields to collect some plants for our herbariums.
Suddenly one student of our group said that he saw a very strange bug that he thought that was related to the family of wasps/hornets.
He pointed to some dried bushes and that insect was hidden inside. I could not do a photo but I hope that you could help me identifying this bug since it surprised me a lot (and even scared me a bit).
From what I remember, this insect had an enormous abdomen (around 5-7cm long and 3-4 cm wide) that had a similar shape to the abdomen of wasps and hornets. The rest of its body and head were very small (around 1cm). It had no wings and I think it had no "hair".
It was mostly black with very few red marks/stripes.
I've been "researching" a bit and the most similar insect I found on the web was the Dasymutilla occidentalis but the insect I found had no hair (or rather I believe so), had a much bigger abdomen and was way bigger than the average "Cow Killer". Also, this bug is native to the US and I live in southern Europe, so I think it's very unlikely that this insect lives here as well (I've found no information about Dasymutilla occidentalis living in my country)
The exact location was (in UTM): 30T 0462625 4447661
(East of Madrid, Spain)
I know this description may be vague, but it is all I've got and I'm very curious about that insect I found. It would be great if you could help me

It will be difficult to id the insect based on your description. What surprises me is the relative wide abdomen, compared to the length and the size of it's head. To me a insect with such a wide abdomen would not look like a wasp. Can you explain why it reminded you of a wasp?

@RHA As I said, one student of our group (who is very interested in zoology) said that this insect was probably related to wasps/hornets and also it had the "typical" "triangular" or "conical" shape that wasps abdomens have. Maybe the head was a little bigger (2-3cm) but the entire insect was around 7 cm


text:
Can someone identify this brown spider in California
Spider found on transit case from California. Approx 1 1/2 inches leg span. Is it poisionus?

It looks a lot like a Kukulcania hibernalis, or southern house spider. This one appears to be a female and if it were to bite you then it would be painful, but not dangerous. These spiders typically keep to themselves so unless you find one hanging in a really bad place it's better just to leave them alone.
For further information you can look here:
https://spiderid.com/spider/filistatidae/kukulcania/hibernalis/

Joseph, once again please provide support for your answer. We as kthat all answers (especially those regarding species ID) be supported by reputable sources that are cited or linked. Otherwise, we're no better than Yahoo Answers :p. I'm sure you know your spiders, but without outside evidence, your post appears no more than a comment. Please see our help page for additional notes regarding writing good answers on our site. Adding citations/sources will surely garner you additional upvotes as well. Thanks!


text:
What kind of red/green/black, spiny caterpillar is this?
It's red and lime green with black on its back and a few white spots as well. Found in Tulsa, Oklahoma (USA).

Looks like a greenish variant of Hemileuca maia – the Buck Moth, which according to here does occur in Oklahoma. This source also suggests that touching the caterpillar (or its relatives) is a bad idea...

 Source: statebystategardening


text:
What about this bat?
This happened in LaGrange GA. We heard some crawling around behind one of the faux-wood shutters on our front porch. So I eased it back and saw this:

If you can't make out the scale, the furry part was about 3 inches long. I didn't want him hanging out right there so I took the shutter off and tried to carry it to the woods but he jumped off. I videoed this:
https://photos.app.goo.gl/NsAFrcry8nJmykzQ7
He definitely had trouble flying but he didn't seem to be sick. He didn't look like a baby to me but I'm not familiar. Any idea what his problem was? He's currently either in the holly bush right next to the house or made his way to the woods in the back yard. I've heard horror storied about rabies so I avoided direct contact the best I could considering how cool this was to see one this close.

Rabid bats can't typically fly or cling upside down. (just like rabid squirrels and raccoons, for example, can't easily climb up trees). As a word of caution, you should never handle a bat you find lying on the ground because its chances of carrying rabies is much higher than one that is flying. Any oddly-behaving (or even oddly-located) bat should be assumed to be rabid simply for safety sake.

However, your bat was found clinging upside down -- a normal behavior, and one that an advanced case of rabies would make more difficult. I'm assuming the lack of flying is due to either an injury you caused to it or simply because you woke the thing up by tearing apart its house. Imagine how you'd stumble about in the middle of the night if a tornado tore off your roof and an earthquake shook you out of your second floor window!

Just an important note for those visiting this page: MOST BATS DON'T HAVE RABIES. For some more quick info: https://www.cdc.gov/rabies/bats/education/index.html

Also, in case your link eventually dies, please convert a portion of your video to a gif to post directly to SE imgur. Try www.ezgif.com to convert and crop your video to an animated gif image. Thanks

Good to know about rabid bats not typically being able to fly or hang upside down. For what it's worth, I was very gentle taking apart his house. Plus, I was there first.

 Short answer
Appears to be an evening bat (Nycticeius humeralis) or little brown bat (Myotis lucifugus).
 Long answer.
You can see a list of common bat species in Georgia through the Georgia Department of Natural Resources. (A high-res image of a visual poster can be seen here).
According to Greenhall and Frantz (1994)1, three of the species found in Georgia are among the species most found in and around buildings: big brown bat (Eptesicus fuscus), evening bat (Nycticeius humeralis), and little brown bat (Myotis lucifugus)
Your image is relatively good, but it does not provide enough detail of key structures to definitively say which species it is. (see Morgan et al. (2019)2 for a key).
If we go simply based on size, the evening bat seems to be closest to your specimen:

E. fuscus is typically 4.1-5.1 inches in length (source), which is larger than your specimen
Your specimen is larger than a typical M lucifugus (1.8-2.3 inches, source).
N. humeralis is more similarly sized (average is 3.4 inches, source).

It appears that your bat has a broad nose, which would hint toward big brown bat (Eptesicus fuscus) or an evening bat (Nycticeius humeralis).
According to GeorgiaBiodiversity.com:

The evening bat is commonly confused with the big brown bat due to its fur color and broad muzzle. However, the evening bat is much smaller and does not have a keeled calcar. The evening bat's rounded tragus distinguishes it from all other small bats except the eastern pipistrelle, which has tri-colored rather than bicolored dorsal fur. The evening bat also has just two upper incisors instead of the four typical of all myotis.

Wait, keeled calcar? Huh?

A calcar is the spur of cartilage coming off the lateral side of the ankle of bats. The image below roughly dmeonstrates the difference between keeled and not keeled.

 Left is keeled; Right is not keeled. Source: Fig 12, Morgan et al. (2019)2
Your specimen does not appear to have a keeled calcar, which would suggest further that this is more likely an evening bat versus a big brown bat.
However, the little brown bat also lacks a keeled calcar....
Though many sources do not directly compare the little brown and evening bat, Morgan et al.'s (2019) key splits these species at the same step, suggesting they have much in common. Morgan et al.'s  differentiating characteristics for these species include:

Hair on hind foot extends beyond tips of claws; tragus long and blunt; underwing lightly furred to elbow: Myotis lucifugus (Little Brown Bat).
No long hair on foot; tragus is short, blunt and curved; underwing, muzzle, and uropatagium are hairless: Nycticeius humeralis (Evening Bat)

According to Greenhall and Frantz (1994)1,

[the evening bat] bears some resemblance to the somewhat smaller little brown bat (M. lucifugus) but can be identified by its characteristic blunt tragus.

To reiterate, the "sharply-pointed" tragus (source) of M. lucifigus and the presence of long toe hairs extending beyond the length of the toe claws (source) would both definitively point toward the little brown bat vs the evening bat. However, neither characteristics is really distinguishable in your photograph.
As such, I don't feel fully confident to rule one out over the other.
It's 3 am though, so perhaps I should stare at your image more in the morning after some rest...I'll update further if I notice anything definitive.

 1. Greenhall, A.M. and Frantz, S.C., 1994. Bats (Myotis lucifugus). The Handbook: Prevention and Control of Wildlife Damage, p.46.
 2. Morgan, C.N., Ammerman, L.K., Demere, K.D., Doty, J.B., Nakazawa, Y.J. and Mauldin, M.R., 2019. Field identification key and guide for bats of the United States of America. Occasional papers (Texas Tech University. Museum), 360.


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What kind of bird is this?

Found in southwest Michigan.  It appears to have fallen from a nest.

It's clearly a heron of some kind. My money's on a juvenile Great Blue Heron, but I will need to double-check their juvenile plumage before I can be sure.

Please provide the approximate size of the bird. Thanks.

The body shape does seem to indicate it's some kind of heron/egret (12 species, of which, have been previously found in Michigan [according to Wikipedia]).
The seemingly large size from your picture (please edit with actual or best approximation of size), the tufted feathers on the head, white face, and the start of a black line on the anterior edge of the eye all suggest that this could be a great blue heron.
Great blue herons are typically grey (not the dark almost black of your specimen), but I did find some photos with nestlings /fledglings with darker plumage, including below:

 Source: Wikipedia


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How does a higher channel density increase speed of propagation of an Action Potential?
If there is a higher density of sodium channels then there will more Na$^+$ flux in the cell. So it's like trying to pass more material through a pipe and therefore the speed of action potential (AP) propagation will be more. This is what comes to me intuitively, but I am not sure about my answer.
Can anyone explain in better words, how the speed of an AP increases with increasing channel density?

Its actually quite opposite: action potential speed is inversely proportional to channel density. That's why myelinated neurons conduct impulse way faster than non-myelinated ones.

Can you give a reference from where you concluded these lines (first paragraph)?

I have edited your post to replace AP by action potential. Such abbreviations will not be familiar to many people and should not be used in titles.

As @another'Homosapien' mentioned in the comments, the reality is actually the opposite:  action potential speed is inversely proportional to channel density.

In other words: lower channel density increases speed of propagation of an Action Potential.

If you decrease the density of ion channels, you increase membrane resistance. This results in less "leakage" of cations, which allows voltages to spread farther and thus reduces the number of action potentials that need to be generated. This results in increased conduction velocity.

 Long Answer
It's important to note two things about action potential propagation:

Each action potential takes time to occur.
The charge (i.e., voltage) that is created dissipates with $ \uparrow $ distance.

In fact, we have equations to calculate both the time a voltage change takes to occur and how current flow decreases with distance.

You can read more about the mathematics behind this and passive membrane properties in general here and here.

Importantly, these equations rely on two constants: length and time.
The time constant, $\tau$, characterizes how rapidly current flow changes the membrane potential. $\tau$ is calculated as:
$$\tau = r_mc_m$$
where r$_m$ and c$_m$ are the resistance and capacitance, respectively, of the plasma membrane. (See this previous answer for an explanation of resistance and capacitance. )
Importantly, these variables partially rely on membrane structure.

c$_m$ (the capacitance of the membrane) decreases as you separate the positive and negative charges.
r$_m$ (the resistance of the membrane potential) is the inverse of the permeability of the membrane.

The higher the permeability, the lower the resistance.
Lower membrane resistance means you lose ions quicker and therefore signals travel less far

But why? This is where that length constant becomes important. The length constant, $\lambda$, can be simplified to:
$$ \lambda = \sqrt {\frac {r_m}{r_e + r_i} } $$
where, again r$_m$ represents the resistance of the membrane and r$_e$ and r$_i$ are the extracellular and intracellular resistances, respectively. (Note: r$_e$ and r$_i$ are typically very small).
Basically, if the membrane resistance r$_m$ is increased (perhaps due to lower  average "leakage" of current across the membrane) $\lambda$ becomes larger (i.e., the distance ions travel before "leaking" out of the cell increases), and the distance a voltage travels gets longer.
 Why am I telling you all of this??
How are the time constant and the space constant related to propagation velocity of action potentials?
The propagation velocity is directly proportional to the space constant and inversely proportional to the time constant. In summary:

The smaller the time constant, the more rapidly a depolarization will affect the adjacent region. If a depolarization more rapidly affects an adjacent region, it will bring the adjacent region to threshold sooner.

Therefore, the smaller the time constant, the more rapid will be the propagation velocity.

If the space constant is large, a potential change at one point would spread a greater distance along the axon and bring distance regions to threshold sooner.

Therefore, the greater the space constant, the more rapidly distant regions will be brought to threshold and the more rapid will be the propagation velocity.

Sooo....
If you decrease the permeability of the membrane (i.e., if you prevent ion pumps from moving ions in/out of the axon), you increase the resistance of the axon membrane, which allows for the voltage created in the action potential to travel farther before dissipating.

By allowing the voltage to spread farther before necessitating the generation of another action potential, you reduce the time it takes for signal propagation.

In other words, if you decrease the number of ion pumps, you increase  membrane resistance (r$_m$). This causes voltage to spread farther and thus reduces the number of action potentials that need to be generated. The result? increased conduction velocity.

Interesting answer, I'll think about it...certainly higher resistance means better propagation of electrical signals, but I am not as convinced that this is necessarily the correct answer to the OP's question. Also, note that ion pumps and channels aren't the same thing.


text:
What exactly is the time constant of an ion channel gating?
Let's take a channel that does not get inactivated, but is only in open and closed states. I understand what m (activation variable) represents. It's the fraction of the gates open.
But what does $\tau$ (tau) , the time constant represent? Does it mean the time taken to open the gate? If tau is higher then it mean more time taken to open the gate?
I'm slightly confused.

It totally depends on what the model is. Can you please add the model equation?

Let's say can you describe the time constant for the activation gate of a sodium channel?

@WYSIWYG Could you please answer?

I need more information. Can you put your model equation in the question? The time constant can mean anything.

Although the membrane time constant is very important in neuroscience, the time constant described in the original question is about ion channel gating rather than the rate of change of membrane voltage.
The "tau" when referring to ion channel gating is indeed referring to how long it takes to open/close.
When the membrane voltage changes, there is a new equilibrium value for the probability of the channel to be open versus closed (note: there can be other states for channels too, but for this explanation I will stick to open/closed). The rate at which this equilibrium is approached from the previous open probability is described by an exponential function, with "tau" as the time constant of that approach. A small value of tau means that the new equilibrium is reached very quickly. This site has a good explanation of the terminology and gating process, as do many others.
Time constants are involved in any system described by an exponential (these are called "linear time invariant" processes), whether decay or increase, and it is equal to the time it takes to progress approximately 63.2% of the way to the equilibrium. The cool thing about time constants (and linear time invariant processes in general) is that it doesn't matter what your starting point is or how far into the process you are, the time constant stays constant and every time "tau" passes you are now 63.2% closer to equilibrium than you were at time t-tau.

According to Wikipedia

In physics and engineering, the time constant, usually denoted by the Greek letter τ (tau), is the parameter characterizing the response to a step input of a first-order, linear time-invariant (LTI) system.

In Neuroscience:
The time constant, $\tau$, characterizes how rapidly current flow changes the membrane potential. $\tau$ is calculated as:
$$\tau = r_mc_m$$
where r$_m$ and c$_m$ are the resistance and capacitance, respectively, of the plasma membrane.

The resistance across the membrane is a function of the number of open ion channels and the capacitance is a function of the properties of the lipid bilayer

Note: the time constant is a "passive property" of membranes because they are intrinsic properties of all biological membranes. [Source].
My guess is that you are referring to some equation reference from Hodgkin-Huxley Model for the Generation of Action Potentials, but without further information about your specific equation, I cannot comment about Tau's specific role in your equation.
Example Application:
This constant can be applied to one of a few equations describing changes in membrane voltage. For example, a fall in membrane voltage is modeled as:
$$V(t) = V_{max}e^{-t/\tau}$$
where voltage is in millivolts, time is in seconds, and $\tau$  is in seconds.

You can read more about the mathematics behind this and passive membrane properties in general here and here.

Again, From Wikipedia:

The larger a time constant is, the slower the rise or fall of the potential of a neuron. A long time constant can result in temporal summation, or the algebraic summation of repeated potentials. A short time constant rather produces a coincidence detector through spatial summation.

Hey, nice answer, but this wasn't the question: the question was about time constants in ion channel gating which is better thought of with equations describing binding or reaction rates, not the membrane time constant, it is a completely separate concept.

@BryanKrause Hmm so it is. Thanks for pointing this out! I wasn't quite sure what the OP was referring to when I first read it. Because of my uncertainty, I tried answering first broadly and then regarding the only tau I knew in this general area of biology. Your answer appears to be the correct answer in this case, though (and thus I gave you a +1).

I Understand that you are referring to the 2-state model of ion channels. In this case, the transition from one steady-state to another is modeled as an exponential decay.
$$
\tau * dm/dt = (m_\inf - m)
$$
The so called "fast" channels have $\tau$ of a few milliseconds, "slow" ion channels have time constants of hundreds of milliseconds or more.
Of course, the 2-state model is a simplified mathematical model of ion channels, but for many phenomenological purposes, it is good enough.


text:
What on Earth is this?
Found in a field near Braga, Portugal in October 2018.

It does not look like a fungus.  It looks like an insect nest - possibly a bumble bee. Did you dig this out of the ground?

Found on the ground. May have been dug up by foraging fox?  Possibly a bee or wasp nuc. Interesting!  Thanks!

I'm voting to close this question as off-topic because without a scale bar, it's impossible to know how large the object in the photo is.

I agree that the OP should provide a scale, but I wouldn't say it's impossible to know -- look at the debris in the picture. Regardless, @Corvus, please add an approximate size of your specimen (perhaps size of each sphere) to avoid having your question closed and to aid someone in providing a good answer. Thanks.

OK, It does not look like a fungus. just going by the single close up photo - I'm pretty sure it is an abandoned bumblebee nest (or that of some similar social insect).  These bees often nest out of sight under logs or under the ground. Below is a link that may help you with a positive identification. I hope this provides at least a hint. Maybe you can fill in the blanks from your knowledge of your local fauna in Portugal.
http://www.bumblebee.org/lifeCcolDev.htm


text:
What insect is this? (England)

Found this in my room and haven't seen anything like it before. It was about 4-5cm long and has wings. Flew away before I could get a better picture.
Photo taken from the Midlands, UK

The angle is a bit hard to see, but did it look like any of these? https://biology.stackexchange.com/questions/41682/identification-of-an-insect-from-midwest-us https://biology.stackexchange.com/questions/73638/what-type-of-insect-in-this?noredirect=1&lq=1 https://biology.stackexchange.com/questions/69158/help-identify-the-insects-i-keep-finding-at-my-house-auburn-wa?noredirect=1&lq=1

It looked a bit more narrow but it's head reminded me a little bit of a stink bugs. I don't think it was that though :/ Hard to tell since it flew off!

Okay; those have only recently shown up in the UK so maybe a long shot anyways, but I think you will have trouble getting a good ID without a more clear picture unfortunately.

i think i have a answer. But it might be schocking :)

I think i have an answer it is this nice guy.

Latin name is Leptoglossus occidentalis.
Short description of Leptoglossus occidentalis:

Western Conifer Seed Bug
  The Western Conifer Seed Bug Leptoglossus occidentalis is a large and conspicuous squashbug, reaching a length of 20mm when adult. It is easily distinguished from all other GB coreids by its reddish-brown body, transverse white zigzag line across the centre of its wings and characteristic leaf-like expansions on the hind tibiae.

Still i think i am right only with genus.

It looks absolutely adorable and looks more or less like what I saw. My measurement may have been a bit off at 4-5cm.

Maybe it is some species from that genus with bigger body. Still i saw it in my home town too, so i ll try to dig more information today.

I'm reasonably sure you're correct at the family level, less so further down ... the OP photo doesn't seem to show expanded hind tibiae.


text:
Can anyone identify this spider for me?
There is a spider on the window of my office that I've been trying to identify for the past few days but can't quite figure it out. My coworker thinks it's a Furrow Orb Weaver but I'm not sure. My office is located near Raleigh, NC and unfortunately I'm on the third floor and the spider always faces away from me, so these are the best pictures that I could get.
[


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What is the difference between sieve cells and sieve-tube elements?
I looked it up and I'm still confused. Apparently, sieve cells lack sieve plates? What does that really mean? It's difficult to find a good picture of either.

All plants have sieve cells, but not all plants have sieve tube elements because they evolved after the plant family tree had started to branch. Only angiosperms have sieve tube elements.
Sieve tube elements are more specialized for their job as transport cells, and can transport more nutrients faster than sieve cells. During their development, the meristem cell divides into two cells: the sieve tube element and the companion cell. The sieve tube element loses its nucleus, vacuoles, and ribosomes when it matures in order to make it easier for its cytoplasm to flow, and so it relies on its companion cell for proteins and carbohydrates. The porous plates between sieve tube elements provide little resistance to water and nutrient flow, and so flow through the sieve tube is more rapid than it would be if there were cell membranes or small pores for it to pass through. The sieve tube elements are wide to make wide tubes, which provide less resistance to fluid flow.
Sieve cells evolved before sieve tube elements, and are a bit less specialized for their job. They still have all their organelles, and are long and thin. Some plants, such as seedless plants and gymnosperms, don't have any sieve tube elements and rely solely on sieve cells for nutrient transport.
References:
Organelles present in sieve tubes
https://en.wikipedia.org/wiki/Sieve_tube_element


text:
Identification of an alpine blueberry type
I'm trying to figure out what kind of berry this is. It can be found all over the Swiss, French, and Italian alps, generally right where ordinary blueberries are (the ones one would eat). However, they are distinctly different:

The flower attachment spot (sorry, non-botanist here) at the tip is square shaped (see photo)
Their leaves turn red much later during the season
The berry is more elongated when compared to ordinary blueberries, a bit of an ellipsoid

Possibly Vaccinium gaultherioides (sometimes considered a subspecies of Vaccinium uliginosum), which are present throughout the Alps.
For example, see InfoFlora*:

 Vaccinium gaultherioides Bigelow, © Konrad Lauber – Flora Helvetica – 2012 Haupt Bern
You can see the prevelance of this species throughout the Swiss alps in the below range map (also from InfoFlora):

______________________________________enter preformatted text here
* the national data center for the Swiss flora
I don't know the flora of the Alps personally and I feel you post lacks enough detail for me to confidently pick and choose among many Vaccinium candidates. From those I've examined, this species seems most visually similar to yours.

That's definitely it! Thank you so much. I didn't know about InfoFlora. Now I have a way to figure out questions like that in a structured manner, which will be very helpful.


text:
Is there a macroscopic amoeba-like organism that lives on land?
In the early 1970s, as a teen, I hiked in Rocky Mountain National Park, going up the base of a mountain. The path went through a deciduous forest (there were brown leaves beneath the trees) and I saw oozing over some of these leaves an organism that looked like an amoeba. It was translucent blue, it had small particles contained in it, and it was about 1.5-2 inches wide (about the size of an oak leaf). It had what looked like pseudopods, and was moving forward by extending one over the leaf ahead of it. It was quite beautiful, as the blue was very clear. I thought it was a slime mold, as we had studied them that year in biology, but find out now that I was mistaken. I googled macroscopic single celled organism and found Gromia sphaerica in Wikipedia, but they seem to be aquatic, like the microscopic ones. Ditto Chaos carolinensis and Polychaos dubium, as far as I can make out.
Any light you can shed on this would be most welcome. I have never forgotten that little guy, and how beautiful it was.

I forgot to mention that it was maybe 1 1/2  to 2 inches wide. The size of an oak leaf, perhaps.

how do you know it wasn't a slime mold? How do you know it's single-celled?

Did it look like this or this or this?


text:
What kind of insect can this be? This appears to be just a shell after and insect went through a metamorphosis process
What kind of insect can this be? This appears to be just a shell after an insect went through a metamorphosis process.

Related: Can anyone help confirm this tiny insect larvae?, Bug Identification: Is this small tubular, black bug..., How to protect my mounted insect specimens..., Varied Carpet Beetle Larvae, What is the name of the critter depicted..., What small insect is this?, What bug is this...

It's a carpet beetle larvae (family Dermestidae).
See here fore more info.
Example:

 Anthrenus verbasci from Wikipedia


text:
Chromosome and chromatid numbers during cell cycle phases
A diploid cell in G1 has 6 chromosomes. How many chromosomes and how many chromatids are present in each of the following stages?
Here is what I am guessing

G1: 6 chromosomes ; 6 chromatids
G2: 6 chromosomes ; 12 chromatids
Prophase: 6 chromosomes; 12 chromatids
Metaphase: 6 chromosomes; 12 chromatids
Anaphase: 12 chromosomes; 12 chromatids
Telophase: 12 chromosomes; 12 chromatids

The chromosomes copy at S phase. So S/G2 checkpoint up to early anaphase has 2n. You are on the right track to understanding the cell cycle, important to note the differences between homologous chromosomes (homologous pair) and sister chromatids, while understanding  ploidy.
During S (synthesis) phase which occurs between G1 and G2 , all the somatic DNA replicates. So every chromosome gets copied and thus  has a sister chromatid.
Animals that undergo sexual reproduction have 2 sets of chromosomes, one from mom the other from dad. The chromosomes of each pair represents homologous chromosomes.
Your answer is almost correct. I believe it could be adjusted to:
G1: 6 chromosomes
G2: 6 chromosomes /12 chromatids Prophase: 12 chromatids
Metaphase:  12 chromatids
Anaphase: 12 separating chromatids
Telophase: 12 chromosomes, 6 one each pole of the cell
These very simple figures explain the principles I mentioned earlier


text:
What is this insect that has invaded my home in Texas?
After the recent floods in central Texas this past weekend I noticed my that bedroom has suddenly been infested with these small insects that have climbed in through the window. Previously, the hole in the window was used by ladybugs who hatched larvae in the room (they didn't survive long).
However, these insects have been here for 3 days now. They seem to disappear at odd times during the day (haven't nailed down a pattern yet) and return a bit later. There are roughly 20-30 of them in my room at a given time. They don't do much and seem very uninterested and passive, mostly just flying around or meandering across the walls on and off. Some of them have wings and others do not (that or the wings are hidden and they just aren't using them).
I would like to identify what this insect is so I can find a way to get rid of them. A picture is linked below. Note in the picture that the white-ish segments on the leg are actually closer to yellow in color.

Myodocha serripes
http://www.americaninsects.net/ht/myodocha-serripes.html
Nice picture! Generally, the body plan of this guy indicates Hemiptera (the 'true' bugs), but the long neck is a bit strange, so a google image search for "Hemiptera + long neck' brought up this strong candidate. It looks like it's distributed in Texas, and is in fact, named for that distinctive neck: "The Long-Necked Seed Bug".
See also the BugGuide.net page for Myodocha

Nice explanation! :-)

Great, this is exactly right, thank you! Now to figure out how to get rid of them...

Well, apparently they come to light and enjoy strawberries...

@Oreotrephes Turning off the lights for a few days during the evenings and trying to seal the window appears to have helped a lot. They still sneak in through the tiny cracks and imperfections in the window but overall it looks like it's working.


text:
Identify an insect (beetle?)

Body size: 30mm
Location: Poland, in the middle of a large meadow
It was flying and landed directly on my cap :-)

After consulting wikipedia it look similar to some of Tenebrionoidea but can't find an exact match.
Help!

This is a Buprestid beetle, and I think the species is Chalcophora mariana. It doesn't look all that coppery in your photos, but the large size and shape is perfect. Their larvae live mostly on pines, so perhaps there were pines close to your meadow?  (Image from Wikipedia)

(Also I feel a need to say that it's gorgeous and that I'm jealous, they are extremely rare in Sweden so I'll probably never see one)

Perfect match, thank you! And yes, there are pine forests nearby. In the real life it also looked quite gray, like in my photos, with only a slight brownish/coppery tint. I hope you will meet your Chalcophora mariana some day :-)


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Why do some Brown Pelicans have orange or reddish parts on their bills?
I am doing research on Brown Pelicans and have photos/descriptions of the breeding and nonbreeding appearances of adults, esp. the California and eastern subspecies here on our southern Pacific, Gulf of Mexico, and southern Atlantic coasts.
One question is really puzzling me:
The birds are described as having long pale bills, some with some brown on them. The bill of the California subspecies is described as acquiring some orange or red during the breeding season (along with the gular pouch which turns bright red/orange/pink). But I see photos of nonbreeding birds (with completely white necks) with either a little or quite a bit of orange on their bills, usually on the lower half.
There are so many pictures like this that the orange cannot be just a breeding color.
Do some Brown Pelicans just have some or quite a bit of orange on their bills, even when they are not breeding? I have looked at just about every link that comes up under Brown Pelicans and no one explains the presence of orange in some of their bills (except during the California subspecies' breeding season). In the official descriptions of the appearances of nonbreeding adults, orange in the bill is never mentioned. I would like to know the answer to this detail in the appearance of some of them!

Maybe it's consequence of the Fukushima disaster?

After doing some reading at the Birds of North America webpage on Brown Pelicans.
It does mention orange on the bill outside of the breeding season.
Brown Pelicans have a greenish gray bill once they are older than 24 days which becomes gray-brown in their first year. At around 12 to 14 months of age, yellow will begin to appear at tip and on the sides. At 16 to 19 months of age, the bill becomes gray-green-yellow with some orange, the orange becomes more distinct at 29 to 37 months.
It is difficult to define the plumage of a Brown Pelican during their first 2 to 3 years; they acquire definitive plumage between the ages of 3 to 5 years old.
Here are the descriptions of their bill in Definitive Basic and Alternate plumages:

In Definitive Basic plumage, proximal end of upper mandible pinkish
orange, distal end buff yellow over pinkish orange, and nail at tip
buff yellow. Lower mandible pinkish orange, except middle section gray
or mottled gray. Proximal end of gular pouch reddish orange (P. o.
californicus) or green-gray (P. o. carolinensis); distal end dark
gray-green. As breeding season approaches, colors intensify; bill
becomes brightest 4–6 weeks before pouch.
In Definitive Alternate
plumage, upper mandible bluish pearl-gray and pinkish on proximal end,
buff-yellow-orange-red over bluish pearl-gray on distal end, and
bright buff-yellow on nail. Lower mandible pale yellow on proximal
third, bluish pearl-gray elsewhere; yellow at maximum intensity when
young being fed; may serve as target for begging nestlings.
Colors
fade with onset of incubation through prebasic molt; upper mandible
gray proximally, buff-yellow and orange over pearl-gray distally, and
buff-yellow on nail; distal two-thirds of lower mandible gray;
proximal end of gular pouch faded yellow-gray (P. o. californicus) or
gray-green (P. o. carolinensis); distal end dark green.

It appears their bill does retain the orange after breeding although it may begin to fade and it does mention how the colour intensifies during breeding.
Reference:
Shields, Mark.(2014).Brown Pelican (Pelecanus occidentalis), The Birds of North America (P. G. Rodewald, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America: https://birdsna.org/Species-Account/bna/species/brnpel

It reminds me of the red spot on the seagulls bills of the classic study by Niko Tinbergen.

In the mid-20th Century, Dutch scientist Niko Tinbergen studied nesting Herring Gulls. He noticed that newly hatched gull chicks were fed by their parents only after they pecked at the adults' bills. Tinbergen devised experiments that varied the shape and coloration of the adult's bill. It became clear that the red spot on the adult gull's bill was a crucial visual cue in a chick's demands to be fed, and thus its survival.

It may be that the same mechanism is used by the brown pelican to elicit a stimulation from the chick.


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Help identify this insect with a fan tail
I am trying to identify this creature... I took the shot in Medellín, Colombia. It is about 1cm in size.

This is the nymph stage of a planthopper, an insect in a suborder of the hemipterans.
The "fiber-optic-like" tail is actually made out of wax! From Wikipedia

Nymphs of many [planthoppers] produce wax from special glands on the abdominal terga and other parts of the body. These are hydrophobic and help conceal the insects. Adult females of many families also produce wax which may be used to protect eggs.

The fact that there are about 12,5000 species of planthoppers and I am fully unfamiliar with the fauna of Colombia, I can only provide a quick image confirming that it is a planthopper. (Perhaps you have a field guide or key available to you to help ID to genus or species)

 Credit: Malcolm Burrows, source
You can find an aditional image of a species more similar to yours here.

thanks so much! I was able to find this other video
https://www.youtube.com/watch?v=jPCRwuPpf9M


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Tiny white very hard cell bug! Please help to identify!
I found these bugs walking on the floor/ wall and on my laptop.  And unfortunately I think they could be in my bed, too, since I bring my laptop to bed sometimes.
I live in a big city in the Netherlands without pets. My house has humidity issues.
I have noticed that the bugs are very tough to exterminate; meaning that when trying to squeeze them it really needs a lot of effort for their size. Their size is about 1 - 2 mm and their color is whitish.

Please note that my lightbulb is having a yellow color.so it makes it look darker than normal. It's more white than looks in the picture

This is a pic of it walking on my screen...

Very likely a tick, though b/c of poor picture quality, I'm not certain if it's Ixodidae or Argasidae. Can you upload additional pictures (preferably of better quality)? A gif of it moving would be helpful to.

Do you have a nearby bird population? Perhaps living outside the window of your room?

Do you work with wildlife or do outdoor work?

@theforestecologist thank you for your reply. I will make sure to reply/ edit my comments. I do have some birds at my window but not that often. I have an office job and I rarely go to a forest or similar.

I found this great mite ID key tool at idtools.org.

Definitely an arachnid and mite (subclass Acari), and very likely a member of the order Parasitiformes, of which there are more than 100,000 species!!
The body plan is not all too different from a tick (order Ixodida), but the movement of your specimen in the video doesn't seem to match that of typical tick. As such, I next began examining species in the related order Mesostigmata.

Unfortunately, according to here, a clear detailed shot is needed to ID this specimen confidently:

In most cases identification of Mesostigmata to family or lower can be accomplished only if the specimen is an adult female. The easiest way to determine the stage and sex of your specimen is to look at the intercoxal region.  Adult females have a genital opening that is almost invariably in the intercoxal region (species of Metagynella are exceptions) and covered by a sclerotized shield which may be truncate posteriorly or continue onto the ventral region.

However....
Mites just always seem to be associated with birds in urban homes, so I thought I'd do some google sleuthing....and voilà! I've found a near and reasonable match!
Specifically, your specimen looks quite similar to mites in the genus Ornithonyssus of the parasitic family Macronyssidae -- these are bird mites (or possibly rat mites). According to here,

The tropical rat mite, Ornithonyssus bacoti, is one of the most common house invading species. The tropical fowl mite, Ornithonyssus bursa, and northern fowl mite, Ornithonyssus sylviarum, are also frequently encountered in homes. The latter two species are found principally on domestic or wild birds. The house mouse mite, Liponyssoides sanguineus, may also be found in structures with house mouse infestations. The tropical rat mite is a parasite on rats. Although none of these species are truly parasitic on humans, they bite people readily, often producing dermatitis and itching.

As for knowing the specific species, citybugs.tamu.edu suggests:

Distinguishing between different species of Ornithonyssus mites to determine whether birds or rodents are the likely source is difficult and requires special expertise.

You can read more about Ornithonyssus bacoti, Ornithonyssus bursa, and Ornithonyssus sylviarum on Wikipedia, and you can see videos of these mites crawling on people here and here.

According to here, Ornithonyssus bacoti can be found as far North as Iceland.

 See below for images:

 Rat mite (Ornithonyssus bacoti). <1 mm;  © Erling Ólafsson; Source: www.ni.is

 Ornithonyssus spp.; Copyright 2014 Tom Murray; Source: bugguide.net
Note: I do not know this group of organisms well, so my answer serves as an (educated) guess to get you on the path toward proper identification...

Thank you very much for taking the time to do all this research. I have further researched with a local organisation and their educated guess was as well that this is most probably a bird mite. To add more on the whole story; I have cleaned all around my house and washed my clothes, bed sheets etc with very hot water. And in general I havent seen any more of these bugs in my room! So I think it was somehow a one time incident.

@Panos thanks for the confirmation. Glad I could help! Just out of curiosity, do you have a mouse problem in your building?

I can't tell much else due to the photo quality, but it could very likely be a tick. Find them all and get rid of them if you suspect there are more. Ticks are sources of some very nasty diseases. If you have pets, check them thoroughly, the ticks will be embedded in their fur.
Please address the Wikipedia link above for more information. The tells here are: it's (1) small, (2) an arachnid based on the number of legs, and (3) lacks a segmented abdomen. The rest of the features are blurry, and so I wouldn't comment on anything I couldn't discern clearly enough. Much of my ID here is coming from personal exposure to ticks in the wild. The nymphs tend to be somewhat translucent like that.

Please provide support/evidence for your answer. thanks!

@theforestecologist Added the rationale I thought made a solid ID. As for sources, I wouldn't recommend much else than the linked Wikipedia article. My ID is largely based on personal experience.

Netherlands has ticks, yes. Here are some distribution maps of tick spp.. There are also quite a few Google hits for "ticks in the Netherlands". Apparently Dutch spring is quite a season for ticks.

@CKM I look at the pictures of the ticks and they look nothing like the ones that I saw in my house. But still could be wrong. I will try to upload a video too; so to make it easier for people to help. Thanks once more for the help!

Actually, now that I've seen the OP's now-added video, the movement of the OP's specimen looks much more like a non-tick mite. So I'm going with subclass Acari: yes, but order Ixodida: no.

@theforestecologist I would have guessed a tick, but your post has convinced me that a rat mite could very well be a good candidate in the 1-2mm range.


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What is a myotube?
If I understand correctly, the following images show the main components in a human skeletal muscle:
From Life: The Science of Biology:

From Human Physiology/The Muscular System in wikibooks:

However, both resources don't mention the word "myotube" even once.
Wikipedia's Myogenesis page says:

Muscle fibers generally form the fusion of myoblasts into
  multi-nucleated fibers called myotubes.

But I don't know how to parse this sentence.
To Add to my confusion, searching for "myotube" in Wikipedia redirects me to Wikipedia's Muscle page.

So my question is:
What exactly is a myotube?
Could you point it out in one of the images above?

Wikipedia now redirects "myotube" to the Myogenesis page, which seems appropriate according to mgkrebbs' answer :)

A myotube is a type of cell which will develop into a muscle fiber.  It is formed by the fusion of multiple myoblasts, and thereby acquires multiple cell nuclei.  The nuclei are in the middle of the myotube cell, unlike the mature muscle fiber where the nuclei are at the periphery of the cell.  A myotube has a tubular form instead of the more typical rounded cell form of the myoblast.  The myotube starts with few or no myofibrils, and goes through a long, gradual development which assembles filaments, myofibrils and other structures of a muscle fiber.  The transition into a mature muscle fiber is not distinct, but might be defined as the point where all nuclei have migrated to the periphery of the cell.
More concisely, the Dictionary of Cell and Molecular Biology entry for myotube says:

(biology) Elongated multinucleate cells (three or more nuclei) that contain some peripherally located myofibrils.
They are formed in vivo or in vitro by the fusion of myoblasts and eventually develop into mature muscle fibres that have peripherally located nuclei and most of their cytoplasm filled with myofibrils. In fact, there is no very clear distinction between myotubes and muscle fibres proper.

Since the diagrams given in the question are for mature muscle, they do not show myotubes but instead show their result: muscle fibers.

Myotube is A skeletal muscle fiber formed by the fusion of myoblasts during a developmental stage;
a few myofibrils occur at the periphery, and the central core is occupied by nuclei and sarcoplasm so that the fiber has a tubular appearance
and u have the diagrams.


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How fast is the blood flow in various vessels?
How fast is the blood flow in different blood vessels, such as the aorta and capillaries?

At rest, during sleep or in the midst of strenuous exercise? In human adults?

I didn't think the flow varied much between rest and high activity? A comparison would be nice. Yes, human adults.

You will have to account for mass balance using the Navier-Stokes equation which accounts for the cross-sectional area of the vessels.

@bobthejoe: Even with a good model of the arterial system, calculating these velocities through a model would probably not work. I'm looking for actual measurements, e.g. as those Larry posted for the MCA.

In the middle cerebral artery blood flow at rest is 73.7 cm/s. After a period of 3 minutes of hyperventilation, blood flow in the same artery decreases to 37.6 cm/s. This is published work.
Vena cava measures: Peak velocities during ventricular systole ranged from 30 to 45 cm/sec in the inferior, and from 10 to 35 cm/sec in the superior, vena cava, also published.


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Why is the Kakapo more attracted to humans than its own kind?
The Kakapo can be seen in this video by BBC. It is said that the species is strongly sexually attracted to humans. Why could this be the case?

The male kakapo (Strigops habroptila) in that video is called Sirocco. Kakapo were (and still are) very close to extinction, so in the 1980s the Kakapo Recovery Programme was launched. As part of this programme, rangers monitor all known kakapo in the wild, visiting their nests and generally ensuring they are in good health. When Sirocco was a young chick, a ranger discovered him in his mothers nest with severe breathing problems. He was brought back to the Kakapo care hut and raised by humans. As a result of this, he imprinted on his carers (see his website!).
Imprinting is common in birds, and takes several different forms. The most well-known form is filial imprinting, where young birds (and some other animals) develop a strong fixated image of who their mother is. They then learn their behaviour almost exclusively from the animal they fixated on. This is well studied in geese, for example by Konrad Lorenz.
However, Sirocco was demonstrating sexual imprinting. This is where young animals (including humans, see e.g. Bereczkei et al., 2004) learn which characteristics are sexually desirable by fixing an image of their parent(s). In Sirocco's case, he imprinted on a human and subsequently saw humans as his species, and therefore potential mates.
The exact purpose of sexual imprinting has been widely discussed (e.g. see Immelmann, 1972). Lorenz suggested that it allowed animals to recognise their own species. However, some imprintable birds will show a preference toward individuals resembling the one they imprinted on, but when introduced to their own species will still recognise them as potential sexual partners. It may therefore be the case that imprinting allows a juvenile firstly to supplement a genetic predisposition toward its own species, but secondly to recognise closely related and less related individuals. Bateson (1978) suggested that this would enable a sexual strategy of choosing mates which are sufficiently unrelated so as not to cause inbreeding depression, but sufficiently related so as not to cause outbreeding depression, and he found an example which bore out the predicted behaviour in Japanese quails.
Sirocco seems not to have the genetic ability to recognise his own species, and according to his website does not associate with other birds.

 Bateson P. 1978. Sexual imprinting and optimal outbreeding. Nature 273, 659 - 660.
 Bereczkei T, Gyuris P, Weisfeld GE. 2004. Sexual imprinting in human mate choice. Proceedings of the Royal Society of London, Series B: Biological Sciences 271: 1129–1134.
 Immelmann K. 1972. Sexual and Other Long-Term Aspects of Imprinting in Birds and Other Species. In Advances in the Study of Behavior, Vol. Volume 4 of, pp. 147–174, Academic Press

@Richard_Smith Great answer.


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When does BLAST fail to align 2 DNA sequences?
This is an assignment that had confused me for a long time.  So I think you guys who study computational biology might be interested. The original question is:

Find the two most similar DNA sequences of length 20 that Blast using a word length of 5 will fail to align.

I am not sure I understand BLAST correctly.
When using BLAST in DNA and protein, they are different. There is a threshold T in protein "seeding" step, which means the seeding sequence is not perfectly matched. However, it seems there is no T in seeding step and we are looking for perfect match and extend them to neighbouring sequence.
So, if there is no word length 5 exact match between these 2 sequence, BLAST will fail.

I am afraid i don't understand what you are trying to say here. Could you please clarify?


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How do plants intake minerals through their leaves?
How do plants intake the fertilizer when it is sprayed all over the leaf surface as a foliar feed?

A nice review by Wocjik (2004)

They absorb minerals through pores in the leaves known as stomata, this is some what similar to the way a medicine patch is absorbed on human skin except for the fact that the human skin has sweat pores instead of stomata.
Here is a animation of them opening and closing on a tomato plant provided by Wikipedia:
sources:

A nice review by Wocjik (2004) (from the comments)
http://www.wisegeek.com/what-is-foliar-feeding.htm
http://en.wikipedia.org/wiki/Foliar_feeding
http://cronodon.com/BioTech/Plant_Transport.html


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If I graft two trees together while young, will they grow as one plant?
If I were to graft two apple saplings together --  by bending the tops toward each other and lashing them together --  will the plants grow as one and benefit from one another, or will they be fighting each other for root space and light? If they would grow with each other, then I could theoretically grow a line of closely spaced fruit trees to any length, and they would be strengthened by each other in bad conditions.

check this out

That is not grafting, if they are not sharing vascular tissue all you are doing is making a weird topiary. apple trees are very often grafted (to prevent inbreeding infertility) so if you want to do it you can find plenty of information.

@John: That's really not why apples (and many other fruit trees) are grafted.  Grafting allows particular varieties to be propagated quickly (varieties don't come true from seed), you can select rootstocks to control height (dwarfing or semi-dwarfing), add hardiness & disease resistance, &c.  You can even graft several varieties of a fruit on a single tree.  See any commercial fruit tree catalog.

@jamesqf I was talking about apples specifically not all fruit. Apple often have a singe branch from a crabapple grafted on to the tree because apples will not fruit with pollen from a similar apple (a gala apple tree will not fertilize with pollen from another gala apple tree for instance) by grafting a very different breed it insures that each tree will fruit as much as it can.

@John that is uncommon, and in commercial orchards it’s pretty much unheard of. Grafting is basically used to propagate cultivars, which don’t come true from seed,   As well as get consistent anchorage, mature height, disease resistance, etc.. Source: worked in nursery for many years, grafting trees, and also had a personal orchard, and maintained several others for many years.

@John: OK, makes more sense when you explain it, though I've never seen or read about it before.  But I tend to prefer heirloom varieties, where it's not so much of a problem.  Or if it is, the nursery says "plant two varieties" :-)  But grafting onto various rootstocks is absolutely the norm.

It is common is apple trees sold for domestic use and I am well aware of the many uses for grafting, I was giving an example a layman might be familiar with. Apple don't come true from seeds for the same reason the grafting I mentioned is done they exhibit strong inbreeding infertility so fruiting apples need constant outbreeding. Cultivars can be bred true from seeds however it is extremely time consuming (15 years +) and very labor intensive, grafting is just faster. Legacy nurseryman myself ;)

There are a couple of answers to this question.  Especially where trees are concerned, you can graft two or more trees onto the same rootstock, or even a single limb into a tree.
But if the graft takes, it won't behave too much more differently than just more branches of the same tree.  Structurally intertwining them will not be different than if you had just taken a single tree's branches to support each other.  The graft will usually only have a single set of roots, from the host tree.  They will not compete.  The tendency will be for the branches to grow apart so that they can independently get their own light.  This is very much like any other single tree.  Not sure about fusing two halves of a tree together - exposing the roots would tend to kill the tree or unsettle it.

What you describe is not grafting it is called inosculation and can prodice some truly impressive results.
Inosculation can sometimes lead to natural grafting but it just as often does not. Apples are a good candidate for this to form grafting but it is not guaranteed. More importantly said trees are often competing for light so you end up having to plant more trees for the same amount of fruit, plus it is extremely time consuming.
As for strengthening that depends a lot on what you call strengthening, they may help each other structurally but joining becomes a liability for say something like drought conditions because you have a smaller root mass per tree.


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Why don't dragonflies wings collapse?
How do dragonflies manage to fly at such high speeds without their wings collapsing? Their wings are thinner than paper, but they do not even flutter. What gives them their strength?

http://jeb.biologists.org/content/206/17/2989 N/m2

Wootton (1992) reviewed the anatomy and biomechanics of insect wings. Basically the wing is a lightweight but strong scaffolding of veins, supporting a thin membrane. The veins are composed by a sandwich of cuticle with a potential space in between. The membrane is also a double-layer but without the space.
In the venous space are is circulating hemolymph and often nerves and tracheae. The wikipedia image is pretty good:

The nerves carry sensory information and the tracheae oxygen.The hemolymph is continuous with the body and thus is able to circulate and hydrate the wing (important for maintaining flexibility). As Wootton says:

desiccation destroys both compliancy and toughness, and a dry cuticle would be mechanically disastrous

So by maintaining a flexible tissue, insects have strong and tough wings that remain light enough.


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Do insects with compound eyes have depth perception?
Do insects with compound eyes have depth perception? They fly as if they do, but their eyes are so close together it seems like the image would be 2 dimensional.

"1001 questions answered about insects" by Alexander Barrett and Elsie Broughton Klots includes the following passage:

Do insects have depth perception? Depth perception of some sort is important to an animal who has to catch its prey; fortunately most
  insects have it to a degree.  Although they do not have binocular
  vision that can be compared with man's, it is true that when one eye
  is covered their depth perception is markedly affected.  The criterion
  of depth seems to depend on the angle of simultaneous stimulation of
  two corresponding points of the retina of the two eyes.

However it does not mention compound eyes specifically.
There may be other methods of obtaining a perception of distance rather than the binocular vision seen in humans.  This paper suggests that there is 'clear evidence' that  some insects perceive depth by moving their head to artificially create parallax, which they can then recognise and interpret as depth and distance.  They cite the Praying Mantis as an example, which does have compound eyes.

keep in mind they do this the same way we do, by having two different eyes, a single compound eye will not have depth perception.

Short Answer:
Yes.
Nityananda et al. (2018) confirmed a novel form of stereo vision by putting tiny colored glasses on praying mantises.

 (Newcastle University, England) [source]
 Long Answer
Background
Stereopsis = the perception of depth and 3D structure obtained from visual info from 2 eyes.
Vertebrates (including humans and all primates) use stereoscopic vision to perceive depth. Each eye sees slightly different images based on their side-by-side orientation, which allows the brain to "calculate" the difference and generate our perception of depth. This is typically accomplished in organisms with 1+ billion neurons in the brain.
Nityananda et al. (2018) have confirmed for the first time that an invertebrate (with only ~1 million neurons) also is capable of stereopsis.

Work by S. Rossel (and others) as early as 1983 had previously suggested this was the case.

Specifically, their work showed that instead of using correlations of image contrast for stereopsis...

Mantis stereopsis...relies on detecting luminance change at positions corresponding to appropriate disparities.

In other words, they propose that mantids are looking for changes in the light patterns over time -- basically, they're only looking for movement.
You can read their paper here.
Sources

Nityananda, V., Tarawneh, G., Henriksen, S., Umeton, D., Simmons, A. and Read, J.C., 2018. A Novel Form of Stereo Vision in the Praying Mantis. Current Biology.

Khan, Amina. 2018. What do you see when you put miniature glasses on praying mantises? A new method for robot vision. Los Angeles Times. Accessed Feb 2018. http://www.latimes.com/science/sciencenow/la-sci-sn-praying-mantis-vision-20180209-story.html.

Wikipedia. "Stereopsis." Accessed Feb 2018. https://en.wikipedia.org/wiki/Stereopsis.

The sense of depth is required to us to orient ourselves in a 3D world. Insects do orient themselves in the exterior 3D world, thanks to the ability to detect the plane of sunlight polarization, that is used as a navigation compass in foraging expeditions and when coming back home.
You can find a good review on Current Biology (Krapp 2007) and a lecture about insect vision from Cornell University.


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To which distinctions does the term "hymenoptera" refer?
Hymenoptera is an order of insects that includes bees, ants, and wasps. A quick search gives the following etymological analysis of the term hymenoptera.

hymen (membrane) + pteron (wing)

Does the term hymenoptera have a firm basis in biology and physiology? In other words, what is different about membranes or wings (or membranous wings) in species of hymenoptera as opposed to species of other orders of insects?

I don't have a definitive answer, but I suspect Hymenoptera is "just a name," albeit a name that has lasted through the phylogenetic nomenclature revolution.
Hymenoptera was erected by Linnaeus in the 10th edition of Systema Naturae (1758). The description of Hymenoptera (membrane wing; p. 553 [hope your Latin is better than mine]) follows that of Lepidoptera (scale wing) and Neuroptera (net wing) and precedes Diptera (two wing).
Classical taxonomy, which Linnaeus was more or less inventing at the time, was based on shared similarities. Those insects which Linnaeus thought more similar to each other than to other insects (e.g., ants, wasps, bees) all shared the characteristic of having a membrane based wing. The scaly wings of moths and butterflies made them more similar to each other.
He needed names for these groups, so he chose logical ones based on outward appearance of the wings: scaly, netted, membranous, or paired. That fact that these major groupings have more or less stood the test of time suggests that Linnaeus picked a good characteristic on which to name his classification of the major groups of insects.

For the most part most of biology is History..

@shigeta: Arguably, most of everything is history :). But this is particularly true for taxonomy, for sure.