The biological study of animals.

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Why are there no wheeled animals?

In physics, "almost everything is already discovered, and all that remains is to fill a few unimportant holes." (See Jolly.) Therefore, on Physics SE, people are veering off into different directions: ...
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Why do smaller mammals move intermittently?

I was watching a nice little video on youtube but couldn't help but notice how snappy smaller animals such as rats and chipmunks move. By snappy I mean how the animal moves in almost discrete states ...
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Why do men have nipples?

I'd be tempted to call nipples in men vestigial, but that suggests they have no modern function. They do have a function, of course, but only in women. So why do men (and all male mammals) have them? ...
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How do cockroaches resist the effects of ionizing radiation?

Cockroaches are very hardy insects. It is known that, among other things, they are able to withstand bursts of ionizing radiation that would kill a human being. The explanations of this observed ...
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What are the trajectories of flying insects?

Many flying insects tend to have very jagged trajectories. For moves of a fruit fly looks like a random walk. Is there any research on the properties of trajectories (e.g. their fractal dimension or ...
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Why do ants live so long?

I was surprised to learn that worker ants in some species live many years. I would have expected a lifespan of a few weeks or months (which is apparently the case for many species). What factors ...
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How is the blood volume of a living organism measured without killing it?

How is the blood-volume of an organism measured without killing it? Note:The blood-volume of an organism is defined as the total volume of blood present inside that organism.
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Do cows produce milk excessively?

Do cows produce more milk than it is required for their calves? It seems like cows are able to provide milk all the time (all year around). Is it so? Or do they, like other mammals, produce milk only ...
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Are there dextral/sinistral higher animals?

For example, almost every dog I've met in my life (more than 20 subjects) uses their right paw touching one while asking for attention. Can it be used as a criterion for calling them dextral? If not, ...
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Are there cats with black skin?

Some mammals can have a black, pink or spotted skin, depending on race - see for example humans or pigs. But I recently learned that this is not the case with mice. Even black furred mice have pink ...
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Do plant-animal cross races exist?

Plants and animals have the following distinct properties: Plants live from solar energy by photosynthesis, they use solar energy to make sugar and oxygen out of carbon dioxide, which gives them ...
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Are humans the only animal that requires “clean water”?

I've seen a number of animals - dogs, cats, squirrels, ducks and geese, etc drink from puddles, some of them were muddy, others had green flora growing under water. Same goes for lakes and rivers. A ...
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Do large animals often evolve into smaller animals?

There are several examples where the largest animals were killed off preferentially due to a major ecological shift: The KT extinction event The Holocene extinction, as well as the major megafauna ...
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982 views

What is this droplet of liquid that comes out of a mosquito?

I have been looking at pictures of different species of mosquito and several times I came across pictures where the mosquito seems to be secreting some kind of fluid. In the pictures one can clearly ...
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556 views

How do porcupines keep from pricking each other while mating?

How do porcupines keep from pricking each other while mating? It seems like they would constantly be scratching each other.
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Why do we grow so much hair on our heads compared to our bodies?

I've been wondering about head hair, facial hair in particular. Human males can grow very extensive beards should they choose to not shave - however you do not really see this in our chimpanzee ...
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Why do parasites sometimes kill their hosts?

It's bothered me for a while now. I understand why a parasitoid would do this, as it only temporarily requires the host, and that not all parasites kill their hosts. There seems to be no evolutionary ...
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How do birds deal with their eyes drying out at high speeds?

My eyes tear up when cycling at 15 mph, which is nothing compared to bird airspeeds. Do birds continuously produce lots of tears and blink a lot, or do the eyes self-moisturize from the inside ...
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1answer
202 views

Do species other than humans have distinct daily feeding patterns?

I have a general interest in complex adaptive systems and I have found that nature and the organisms within it is a perfect natural case of a rich adaptive system with a lot of possibilities for ...
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Is the appendix a vestigial structure in all vertebrates?

In humans the Appendix is a vestigial organ. Does it serve no apparent purpose in all the vertebrates that have one?
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Why is there a difference in the rotation of the tail fin in fish compared to marine mammals?

I've been thinking about this one, but I can't seem to find what causes this difference. All fishes that I've seen have their tail fin positioned vertical: But all the marine mammals I know have ...
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How do insects breathe?

Do ants even breathe? If they don't, how do they stay alive? On what resources do they depend upon to stay alive? How are they different form mammals?
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1answer
346 views

How do members of cryptic species know who to mate with?

According to Wikipedia: In biology, a cryptic species complex is a group of species which satisfy the biological definition of species—that is, they are reproductively isolated from each ...
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Help identifying what this is in Crayfish gills?

this is my first time posting here. I was in my Zoology lab doing a dissection on a Crayfish when I noticed these hairlike structures within the gills. They were very "snappy" and fine, and would ...
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Was the recent “conservation hunt” of a black rhino supported by science?

CNN recently covered a sanctioned black rhino hunt in Namibia by Texan Corey Knowlton, who bid US$350,000 for the license. In the story, he claims that the hunt was actually supporting conservation of ...
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How do we know that dinosaurs were related to lizards and/or birds?

Do we clearly know what the living closest relative of the dinosaurs are? And connected to the first question, in scientific manner how do we know these relationship between extinct species and living ...
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Why we have no enzyme to digest cellulose?

As we know, cellulose is the most abundant polysaccharide in nature. Why don't we have any enzyme to digest cellulose?
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Help identify this worm-like thing

Many instances of this worm-like creature were found in a water system for a mountain cabin in the Sierra Nevada mountains of the US, in late June / early July. The water system collects water from ...
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Is there any relationship between heartbeat rate and life span of an animal?

Is there any relationship between heartbeat rate and life span of an animal? Do they belong to a cause-and-effect relationship or are they both caused by some phenomenons or a common cause?
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Fish “coming back to life” after being frozen

I've encountered a clip on Youtube showing a goldfish thrown in liquid nitrogen and immediately after to normal water and swimming normally. In the explanation to the clip it says: For everyone ...
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1answer
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Why are fly not scared when landing on a monitor with changing graphics?

I have been wondering why would insects in general, not be scared when important changes happen on your monitor where they have landed... If you move even just a finger, they are scared to death and ...
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1answer
343 views

Examples of animals that co-opt toxins?

It is known that there are animals that acquire toxins through their diet or through their surroundings. The examples I know of include butterflies stocking up on alkaloids/glycosides while in the ...
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How does a jumping spider manage to “jump” on the ceiling?

I just witnessed a small jumping spider jump on some kind of louse or bed bug on the ceiling. How does it do that without falling? I have yet to find a high-speed-camera video of a jumping spider ...
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1answer
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Do fish break a water molecule to absorb oxygen?

How do fish separate oxygen from H20 & consume it? Do they break the water molecule and absorb the oxygen only?
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300 views

What was the reason for some plant and animals to become giant in course of evolution?

The dinosaurs, mammoths, giant plants etc are known to be bigger than modern animals. I wonder why they had been lived and why they are not living now? I really don't know much but is it something ...
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How does a woodpecker not give itself concussions?

How does a woodpecker go about smacking it's head into a tree without killing itself?
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Are there any pre-Holocene venomous animals?

The novel (and subsequently movie) Jurassic Park featured a dinosaur called Dilophosaurus, that was purported to be venomous and had an ability similar to that of the extant spitting cobra. ...
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How do baby animals that primarily subsist on cellulose get their initial gut flora?

In the case of mammals like giraffes and koalas, is that bacteria common on the plants they eat so when a baby starts to try to stick something besides its mother's milk in its mouth, it can't digest ...
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How many cells does the smallest animal have?

Note: question rewritten to prevent misunderstanding and make it more answerable I know that some small animals like C. elegans display surprising sophistication with a very small number of cells. ...
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Why do pandas have a high probability of giving birth to twins?

According to the BBC documentary "Wild About Pandas", about half of panda birth result in twins. Why do they have such a high probability compared to other mammals? What factor(s) control that ...
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How can an albatross stay airborne for months?

Albatrosses, of the biological family Diomedeidae, are large seabirds allied to the procellariids, storm-petrels and diving-petrels in the order Procellariiformes. They range widely in the Southern ...
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What kind of skull is this?

We found this skull on a beach in southwestern Sweden, and are curious as to what kind of animal it was.
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How best to count bees entering and leaving a hive to measure hive activity?

This is my first question here, so I apologize for all mistakes I could have possibly made. I'm a high school student in East-Central Europe and I need to complete some research for a biology contest ...
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Species with reproduction barriers that can both reproduce with a third species

To start with, I do not have a sound knowledge in biology or any formal education in the area. I was told that one of the definition of a species is a reproductive barrier, which means that if two ...
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What's the name of this bird?

This morning I saw a bird that I have never seen before. Since it was quite big, I'm very interested in knowing its name. The bird was quite big, at least 2-3 times of a common blackbird. The wings ...
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What is the smallest scale at which blood vessels, nerves and other structures are deterministic?

Super simple question, but I can't find the answer on the Internet (and I'm in a foreign country so the library is not English.) As the title says, what is the smallest scale at which blood vessels, ...
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How many mice are on the Earth?

We are 7 billion human beings on the Earth. But how many mice are there? How would you estimate such a number?
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Can canines communicate with each other using gaze direction?

After researching why humans have white scleras when most primates have dark scleras, I stumbled upon the cooperative eye hypothesis. It proposed that white scleras may have evolved on behalf that it ...
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1answer
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Can a lizard shed a regrown tail again?

Some lizards are famous for their ability to voluntarily shed their tail to elude predators (Autotomy). After a while, the tail will be regenerated, though with slightly different qualities, as ...
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Why does the butterfly have a cocoon stage in its life cycle?

Why does the butterfly have a cocoon stage in its life cycle? It could have simply grown up within the egg/cocoon, and emerged as a butterfly. Instead it is first an egg, then a worm, then a ...