The biological study of animals.

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The Evolution of Hugs

Obviously humans like hugging, and this is also true of other species like monkeys. But I have read that dogs do not like hugs at all. Why have some species evolved to enjoy hugs, and others are ...
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Identification of a spider from my basement

It's a little over 1" long including legs, and I found it in my basement in Pennsylvania. My guess is a funnel weaver, which would be nice since then I can free it (right?) from the tin can it's ...
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40 views

Predator prey interaction [on hold]

I went through a line in my textbook which read: "But for predators, prey species could achieve very high population densities and cause ecosystem instability." I was not able to understand the ...
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1answer
25 views

Could a large constrictor kill a small animal?

According to this article there was a python whose body circumference was 85cm. This means its diameter was 27cm. Would it be possible for this snake to constrict animals that are about the same ...
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37 views

Is there evidence to suggest that sharks from prehistoric times live in the deep of the oceans?

I've had friends see the boat and giant teeth of a giant shark attack of a boat in Japan. (Teeth larger than a great white). [I can't find anything about this on the Internet]. In addition, this ...
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How much do crocodiles eat?

How much do crocodiles eat? The closest I found to an answer was on German wikipedia, where it says that adult nile crocodiles eat "only about 50 full meals a year." While interesting, without knowing ...
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Why people have less hair than other primates? [duplicate]

Well as you can figure out, most primates such as monkeys, gorillas and chimpanzees, have all their body covered with fur. As we know they are evolutional "relatives" to us humans, but we dont have ...
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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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35 views

Spatial dimensions for an animal

I'm reading a review paper. They say: The position of an object in head-centered coordinates (that is, relative to an animal's head) can be defined along three axes: the medio-lateral (radial) ...
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Do any terrestrial herbivores use auditory crypsis for predator avoidance? [closed]

Some terrestrial predators "stalk" their prey: they sneak up on it slowly, maintaining a low profile, while keeping as close to silent as possible. This makes sense from an evolutionary perspective: ...
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How the Phereoeca uterella (casebearer) is formed? [closed]

Does anyone know how the Phereoeca uterella known as the casebearer is formed or born?
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62 views

Do ants use something similar to the honey bee “waggle dance” to instruct the rest of the colony where to find a food source?

In the 20 years since we built our home, we've just recently had our first ant infestation. I'm familiar with the fact that ants leave scent trails to find their way back and forth between the ...
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118 views

Why Crocodiles don't eat Hippos?

I have been following documentaries about crocodiles and amazingly, crocodiles and hippos apparently seem to live happily in the same pond together without attacking each other. Why is it so? Like ...
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Insect making continuous sound in summers

In deciduous to tropical-deciduous forests and residential places with such vegetation I have found this insect to make continuous sounds all through the day (even in nights sometimes) during the ...
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Why do horses recycle their endometrial lining while humans don't?

How does not recycling the endometrial lining of the uterus benefit humans (and other organisms that menstruate), while recycling it is beneficial to horses (and other organisms that undergo estrus ...
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2answers
369 views

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 don't rats have a gallbladder, unlike other rodents?

It has long been known that rats do not have a gallbladder, though other species including humans, monkeys, cows, reptiles, dogs and mice, all have a gallbladder. In this paper from almost 100 years ...
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Do animals have different taste preferences within the same species?

Humans (especially children...) seem to dislike certain foods or drinks, that other humans seem to like. Common examples are coffee, french cheeses, olives, milk, fish and cabbage. Are there examples ...
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Humans genetic/phylogenetic “next relative” in central Europe? [closed]

What species in central Europe in the phylogenetic tree shows the closest difference in time to the most recent common ancestor with Homo sapiens?
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103 views

What made this black cluster on a leaf?

I found this black slug-shaped thing on a leaf by my pond in western Sweden. It's about 15 mm long, positioned on a vertical leaf (I bent it to take the picture). And I don't even know where to ...
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Are there any individual animals that can thrive in a wide range of core temperatures? [closed]

Surely, some cold blooded animals are in a position where they can't escape the changing temperatures the environment throws at them, so natural selection would have enabled them to thrive in a wide ...
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1answer
136 views

What were the camels' humps good for back in the polar areas?

I've heard that camels lived in the North America formerly and just in the last few thousands years they've migrated to the hot deserts. Thus they allegedly utilized the adaptations against the cold ...
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3answers
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Why are turtles classified as reptiles and not amphibians?

I understand that turtles are reptiles because like all reptiles, they have scales on their body. But turtles (specifically sea turtles) live on both land and water, very much like amphibians. Also, ...
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Why don't animals need filtered water? [duplicate]

Almost 10 years back when I was a kid, we had a picture in our school text of wild buffaloes drinking water from a river - which was visibly muddy. I asked my mother of why we need to drink filtered ...
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41 views

Is the knee locking mechanism present in animals?

We study in human anatomy that when the knee is in full extension, the femur slightly medially rotates on the tibia to lock the knee joint in place. This reduces the work required to be done by the ...
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93 views

Can animals also get Down syndrome?

I heard that animals cannot get Down syndrome or trisomy. Is that true and why can't they get it? They also have chromosomes.
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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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468 views

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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How much to larvae eat? (1. general and 2. specifically larvae of the bread beetle stegobium paniceum)

I'm no biologist or anything and thus the question might seem odd, but I couldn't find an answer anywhere on the web. I'm looking for information about how much larvae eat. To be exact I need to ...
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122 views

Which of the following lacks DNA?

a) An Enucleated ovum b) Mature RBC c) A mature spermatozoan d) Hair root According to me, there can be 2 answers, a and b because an ovum whose nucleus has been removed lacks DNA. And also, ...
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24 views

Which animal that lives in the forest makes this noise?

Which animal makes this noise? Link to audio file The file was recorded next to a forest in Germany.
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7k views

What organs are absolutely needed by the human body?

The title is my question: what organs are absolutely needed (fatal if injured/removed) by the human body and perhaps animals in general? I'm not asking which organs are mechanically replaceable, but ...
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1answer
43 views

If crocodiles are k-selected, why do they supposedly “not age,” as in avoid senescence?

I recently saw a few sources stating that Crocodiles do not biologically age, implying negligible senescence. Basically, a 70 year old crocodile is in the same physical/health condition as a 7 year ...
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747 views

Are all quadrupeds edible? [closed]

I wonder if all quadrupeds (or, mammals, at least), are edible? From what I have collected, even down to fish, everything is edible apart from being sick or infected, and, apart from some glands ...
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124 views

What species of fox is this?

I found this picture of a fox in a news article about arctic foxes in Sweden (source), but I'm not sure whether it is actually an arctic fox. On the one hand, it has white fur, which is the correct ...
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Why would a mother reject her offspring if it has been “interfered” with by humans?

There was a recent incident at Yellowstone National Park in which tourists placed a bison calf in their vehicle, and that eventually led to the calf being euthanized. The National Park Service issued ...
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Do all parasitic worms lack tango receptors on their skin?

I read that the parasitic nematodes lack tango receptors on the surface of their body. Is this true for all the parasitic worms?
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53 views

What nocturnal animal sound am I hearing in the trees in Maine?

Every year, during late summer nights (usually around 9:00 pm) in Maine, I hear a noise coming from high up in the trees. The trees I hear it from are mostly maple or conifer, but where I live there ...
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Dogs bark at familiar person in Santa costume. Why? Don't dogs trust smell over vision?

Last night 10 humans and 2 dogs spent Christmas together. At some point, one human dissappears for a few minutes and comes back wearing a full Santa outfit. Upon respawning, the dogs start barking ...
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84 views

What is this animal? [duplicate]

Can someone tell me what is the name of this one? Then I can check a little more about it.
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1answer
78 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 sea)....
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1answer
36 views

How do mosquitoes orientate in the darkness?

An annoying mosquito (Culicidae) which kept me awake nearly the whole night lead me to this question. I have heard that mosquitoes can smell CO2 which could help them to orientate in the darkness, ...
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1answer
4k views

What is this crawling next to my house?

I just found this outside my house while walking the dog. I was thinking it's some kind of slug? It's been raining a lot lately and today, so maybe that has something to do with it being on the ...
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1answer
100 views

Blood clumping in mosquitos

Will a mosquito die due to blood clumping if it sucks blood from two persons having different blood group? What will happen in its gut? Is there any mechanism to avoid clumping ? Or mosquitos know ...
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Can you suggest me some books/articles about how female birds indicate receptivity to copulation? [closed]

Where can I find informations about the topic? I need to find some examples. I also really need this particular information: I know that many female mammals display lordosis behavior that indicate ...
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Extiction of non-mammal Synapsida

I am following M.J. Benton's Vertebrate Palaeontology, which explains how many groups of Synapsida were already extinct in the Mesozoic Era, with one obvious exception being the group of Cynodontia, ...
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Cells of Zona pellucida

My textbook states: Blastocyst hatches out by lysis of Zona pellucida with the help of the enzyme strypsin, Later the cells of Zona pellucida gradually disappear. We know that Zona pellucida is ...
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What did William Harvey discover from experimenting with deer?

On his wikipedia page, I read the following: In particular, Charles' hunting expeditions gave Harvey access to many deer carcasses; it was upon them that Harvey made many observations and ...
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1answer
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What is the Cordil that Edward Topsell describes?

In his "History of four-footed beasts and serpents", Edward Topsell describes a "serpent" called Cordil. Since he lists everything that crawls on the ground as a serpent, regardless of being a reptile,...
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Do male animals visually perceive females as more/less attractive?

If we somehow remove pheromones, do animals experience a phenomenon similar to human "visual beauty" when looking at members of the opposite sex? For example, given a set of 20 female ducks observed ...