The biological study of animals.

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Why do snails come out after the rain?

Many times, when there is rain after a long time, snails come out afterwards, and you can see snails and slugs everywhere! I have two questions: Why do they come out after the rain? Where are they ...
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148 views

Why are cancer rates low in large animals?

Large animals generally have more cells and live longer than smaller animals. For example, bowhead whales live up to 200 years and weigh up to 100 tonnes, as opposed to humans (living ~71 years and ...
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43 views

How can birds keep their eyes moist during flight? [duplicate]

Mammals have an upper lid and small mass of tissue in the upper corner known as nictitating membrane. This helps keep the eyes clean; birds can moisten their eyes in flight using this membrane ...
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Evolution of spider webs?

Web making seems like a fairly complex behavior built from a pretty strong material. So how exactly did it evolve? Do we have any clues about what kind of features/behaviors preceded web making and ...
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93 views

Which class of animals constitute the largest biomass?

I found here that species-wise it is cow. But, collectively, insects may exceed even mammals. So, which class of animals constitutes the largest biomass?
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Please identify organ

This is the gut area of an Eastern Grey Kangaroo taken of a property in the Southern Highlands of NSW, Australia. The top red organ appears to be the spleen but what is the elongated tubular organ ...
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68 views

Which Darwin book (and today edition) is illustrated by his own drawings?

I am interested in buying Charles Darwin books and mostly drawings (nowadays editions, I am not a collector). Please, can you advise in which book and which edition I can find the most of his ...
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Is lung size/shape a factor in long-continuous running of animals?

Apart from other factors, does lung shape/structure/size play any role in long-continuous running animals. Is there any similarity in lung structure between different long-continuous running species? ...
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118 views

The biggest underground living animal

It's easy to find informations about the biggest animals at land / at sea / in the air. But what was the biggest animal that ever existed, that lives underground? No animals that were forced to live ...
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232 views

is a musk deer's musk pod in its abdomen, its back, or its bottom/rear end?

I have read/heard different things about where a musk deer stores its perfume Some links say it stores it in its abdomen just in front of its penis. Others say the rectum(by which I suppose they ...
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Why are there no known animals with an odd number of legs?

In my 6th grade science book it is said that there are no three legged animals, and that no animal with an odd number of limbs exists. I checked Wikipedia and could confirm this: There are no ...
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51 views

Was this snake behaving abnormally?

This morning, I walked out front of my house to find a medium-sized snake balled up on my driveway beneath my motorcycle. I spotted it from my porch so I didn't walk any closer. I believe it was a ...
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45 views

Biological Evolution outside of Earth [closed]

What drives evolution forward? I heard that climate change drives species to evolve and adapt. Is there any other mechanism that is encoded in our DNA by which species can over abrupt changes, evolve ...
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271 views

Can animals like squirrels leave “gifts” or tribute for humans?

I've heard anecdotal reports of squirrels bringing up gifts to a person's house after that person left out food for them. Sounds bizzare and unbelievable, until I actually saw some kind of a nut right ...
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Why do I often see male robins with female robins?

Even when it is not breeding season for robins I still often see male robins with female robins. But why? I know that the male robin often chirps to find female robins within his territory. I also ...
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53 views

Do any predatorial animals attempt to appear smaller?

There are many animals that have behaviors or characteristics to make themselves appear larger than they are as a defense mechanism, such as butterflies have large eye patterns on their wings. Are ...
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200 views

What is a subspecies?

Within a species there may be subspecies that are named using trinomial nomenclautre. For example the Grizzly Bear, Ursus arctos horribilis is a subspecies of the Brown Bear Ursus arctos. The ...
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79 views

Do all mammals have a Ventricular system?

I am familiar with the human Ventricular system that circulates Cerebrospinal fluid. This is needed among other reasons, to suspend the heavy human brain, and for injury protection. Do all mammals ...
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433 views

Why Egg shell is not called a cell wall?

Egg is a single cell and has a outer hard covering outside inside which there is a cell membrane. Then why isn't the egg shell a cell wall? Is it because no exchange of materials take place through ...
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127 views

Which primates can swim underwater?

I saw a documentary awhile back and they were profiling a certain species of monkey which regularly swims underwater. I can't recall which species it was but they said it was rare for primates to do ...
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97 views

What type of jellyfish is this

I have been swimming in the seas around Minorca and saw a jellyfish I had not seen before. I have tried to find it and have (eventually) found 1 single picture of the jellyfish. The problem I ...
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How much oil you can get from a dead animal

This is purely speculative, but is there a formula to calculate how much oil you can get from 1 Kg of biomass? I've seen bioreactors in farms where they put dung, vegetable scraps, and all bio ...
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27 views

can the regeneration mechanism be used in humans that of lizards?

how lizards grow their tail again like is there any mechanism or specific protein which helps them to regrow their tail? can the mechanism of regeneration be used in humans to regenerate our limbs is ...
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124 views

How to know the gestation time of pregnant mice?

In lab mice I wish to establish how many weeks my animals are into their pregnancy. Is there some way?
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400 views

Why do men grow facial hair?

Ancestral facial hair. Our closest ancestors, the chimpanzee and bonobo, both grow facial hair around the mouth area. What is noteworthy is that this is the case in both males and females of the ...
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How octopus develops its imitation skill?

I've watched one documentary about a Mimic octopus which they can imitate another animals in several form e.g. a Lion fish, a Sea snake, a Flatfish, etc. My question is how these octopuses can have ...
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How do birds avoid mid-air collision?

Across from me there is a large flick of Pigeons and Ravens that like to nest on the roof. They swoop and dive and fly all over. Sometimes the whole flock lifts off at once. My question is, how do ...
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151 views

The heart of a Pigmy Shrew beats 1300 per minute then why is it so fast?

A pigmy shrew is such small animal. Even with such fast heart beat their average life span is 1.5 years. So can we consider faster heartbeat not good for health?
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277 views

What kind of insect is this and what is it doing?

I live in Denmark, Europe and found these 2 insects on a tree. I'm interested in the big fly and have the following questions: What kind of fly is it? What is it doing with the little fly?
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Insect identification: white spotted beetle

3 pairs of legs, a pair of antenna, wings absent, compound eye, 4-6 centimeter approx. in size. I found this beetle at my door, in Pune, India.
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How did zootoxins evolve?

I've always wondered how toxins in certain organisms have evolved. Particularly, organisms that produce toxins as a deterrent to predators as opposed to organisms that use it to paralyze their prey. ...
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Why do orcas eat only the tongue of whales, liver of sharks, etc.?

I noticed that although killer whales are clearly the top predator living in the present oceans, some of them appear to be very picky with their meals. After spending hours hunting down a whale, ...
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Madrid, Noise by the river: Bird or cricket?

I currently live in Madrid, Spain. In July there was a loud animal near the river, in an out of town area surrounded by grassland, with trees along the river. It's continued into August, though it ...
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77 views

Identification of a small mammal

Could someone help with identification of this small mammal? Is it a possum? A dormouse? It was photographed in Sukhumi botanical garden, in Abkhazia (west of Georgia, on the shores of the black ...
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Endothermy in different species

Birds and mammals are both endothermic, meaning they metabolically generate the heat they need to keep their body within a certain temperature ranger. But birds are closer relatives to reptiles than ...
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Are dogs affected by dwarfism?

My husband and I noticed a dog today that looked like a smaller version of a purebred Border Collie, although it didn't appear to be a puppy. It made us wonder if other animal species experience ...
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How do animals end up in remote areas?

I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough. They usually ...
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692 views

Why are lions the only social cats?

We know that almost all cats are solitary. How did the Lions (Panthera leo) end up social animals? Do we have an explanatory evolutionary path describing how the Lions became social while the rest of ...
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Why do crabs spit?

Last year I photographed this juvenile Sally Lightfoot Crab (Grapsus grapsus) 'spitting' (click for larger view): I thought I'd look up more information on this behavior, but couldn't find any ...
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Do any amphibians start their lives on land?

Most amphibians - at least, all the ones I know of - start their lives in the water (at least, after they hatch). They then spend time maturing before venturing onto land, where they can breed. The ...
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Is there a mechanism by which mammals lose interest in a partner after mating?

I'm reading the book called "Cupid's poison arrow", which revolves around a rather simple assumption: most mammals, including humans have a genetic program that is responsible for ever increasing ...
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409 views

How do other primates treat their fingernails?

Do all primates have to trim their fingernails in some way, or do some primates' fingernails wear off through natural use? Also, is constant nail growth common to all primates?
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Do domesticated animals necessarily live longer than wild animals? counterexample wanted!

Generally domesticated animals do not need to worry about their food and other predators. They have a lower probability to get sick. However, it seems there is no sharp difference between wild pigs ...
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Saline solution for animals

A popular "well-known fact" is that all creatures on Earth consist mostly of water (i.e. H2O). Indeed, a liquid called "normal saline solution" is just a solution of 0.9% sodium chloride in distilled ...
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51 views

Are grasshoppers monogamous?

Noticed two grasshoppers jumping together on the porch, and started wondering if they are monogamous? I am aware they have males and females.
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1answer
175 views

Is it theoretically possible to restore the Tiger population to 100,000?

The current global Tiger population is roughly 5100 according to Wikipedia. With habitat destruction and poaching continuing and no effective improvement in conservation, most likely the Tiger ...
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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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Do animals commit suicide? [duplicate]

Do we have documented cases of animals purposely and consciously trying to end their own life? What leads to animal suicide, and is it preventable? I've heard mixed answers from various biologists. ...
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1answer
404 views

How can bats hear such high frequencies?

I attended a talk that glossed over some biology as it was talking about a certain protein. The speaker mentioned humans can hear up to, often less than 20kHz frequencies, whereas bats can hear up to ...
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Which taxonomic classification schemes are most accepted?

Since the taxonomic classification schemes followed by universities around the world are different I wish to know which are the most accepted classification schemes till date concerning the following ...