Questions tagged [mammals]

Questions related to mammals, animals that nurse their young, have a neocortex, and three middle ear bones.

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59
votes
5answers
41k views

Why don't mammals have more than 4 limbs?

Arthropods have 6 or more limbs and arthropods with 6 limbs appear to move faster than arthropods with 8 limbs so I wonder whether this might have something to do with fast and efficient locomotion. ...
36
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2answers
17k views

Are there any non-mammalian species known that lactate?

Are there any non-mammalian animals that produce milk to feed their young, or are mammals the only milk-producing animals?
23
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1answer
8k views

Why can't humans drink sea water?

Why can't humans drink sea water? It would seem to be a huge evolutionary advantage for an animal to be able to drink sea water rather than have to rely on fresh water, and it's provably not ...
22
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3answers
55k views

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 ...
21
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2answers
31k views

How and why did mammals go back to the oceans?

If I understand evolutionary biology correctly, mammals first evolved on land as small, rodent-like creatures, in a time when reptiles were dominant on land. Eventually, they diversified into the ...
21
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1answer
100k views

Can a person really die quickly from biting their tongue?

A common trope in certain circles (like Eastern martial fiction), is someone committing quick suicide by biting his or her tongue. But is this really possible? The internet turns up millions of ...
19
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2answers
5k views

Why is wombat excreta shaped like cubes?

I've heard that wombat excreta is cube shaped, but I don't understand how that can happen. Has anyone studied the phenomenon? What would the evolutionary pressure have been to cause this?
19
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2answers
16k views

Evolutionarily, why do male rats and horses lack nipples?

Developmentally male rats don't have nipples because (reddit) Testosterone release in the fetal male rat happens before the stage of mammogenesis where the teat is formed whereas other species halt ...
19
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1answer
629 views

What effect does a bat's echolocation have on other bats?

Bat echolocation is a perceptual system where ultrasonic sounds are emitted specifically to produce echoes. By comparing the outgoing pulse with the returning echoes, the brain and auditory nervous ...
18
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4answers
622 views

What sea animal is this?

I am in a remote village and a young boy (second pic holding tail) says this thing is his friend. This creature is safe, we held it for pictures and released it after. None of us know what this is and ...
17
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1answer
3k views

Could a fetus properly develop in micro/zero-gravity?

I suppose another way of looking at the question is: how important is gravity for the development of mammal fetuses? And if things would go wrong, what sort of things would they be, and what would be ...
13
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3answers
3k views

Why is mammal coloration so dull?

I have seen species of birds, insects and fishes with splendid colours. But when it comes to mammals (including us humans), they almost always appear in shades of brown, grey, orange, or in black and ...
12
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2answers
171 views

Can dolphins actually communicate linguistically?

Humans use "language." By language, I mean the thing I am using right now to talk to you. I know dolphins and orcas have very complex communication systems and also seem to process linguistic and ...
11
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1answer
1k 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 ...
11
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2answers
2k views

How conscious are mammals that mating leads to pregnancy and offspring?

Does a pregnant female mammal know that its pregnancy is the consequence of a previous mating? Or are humans the only mammals which are conscious of it?
10
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2answers
3k views

What hair do aquatic mammals have?

I'm reading an essay on the creating of the Mammalia zoological classification (Londa Schiebinger, The American Historical Review, Vol. 98, No. 2 (Apr., 1993), pp. 382-411). It contains the statement ...
10
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1answer
5k views

Mammal body density

Human body density is approximately 1 kg/l (same as fresh water) - which is not surprising (at first) given that we are 70% water, and is surprising (on a second thought), given that the other 30% can ...
9
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2answers
815 views

Goats are so fearless but sheep are not. Is there any genetic difference responsible?

As you see in the picture goats (not only wild goats) are so fearless, but I never saw any sheep do this. What is the source of this difference in behavior?
9
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2answers
49k views

Do male mammals other than humans have nipples?

When I grew rabbits, I had a pair, one male and one female. And while the female's nipples were quite prominent, especially after giving birth, I don't remember the male having any nipples at all. Do ...
9
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1answer
2k views

Why do squirrels have twitchy bushy tails?

Whenever I see a squirrel in the woods, it is always the big bushy tail flipping around that gets my attention first. A pray animal with a big bushy flag calling attention to it's self seems to be ...
9
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1answer
139 views

Do camels pose an environmental threat to kangaroos?

Camels, once used for transport across the Australian outback, were set free, and are reproducing at an uncontrolled rate in the empty interior of Australia. Do the ecosystems of camels and ...
9
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2answers
206 views

How can bats achieve good resolution with wide beams?

I have been reading about the echolocation system in bats. papers state that bats tend to produce a sonar beam that has a beam angle (-3db) of about 30-40 degrees. This would be considered a wide beam ...
9
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1answer
2k views

How did dolphins acquire their dorsal fin?

I had been thinking bout atavism when I saw a picture of a dolphin. I had seen it before, but suddenly the dorsal fin startled me. How did this dorsal fin evolve? Is it some atavism from eons ago, a ...
9
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1answer
260 views

Identification of a mammal in cage

This unidentified animal was trapped in northern part of Kerala State India and images circulated through social media. Doea anyone know what species this is?
8
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2answers
990 views

Why haven't land animals evolved beyond urination?

It occurred to me (while urinating) that this would seem to be selected against because water is a scarce resource. Why are we constantly losing water we don't need to through urination? What is ...
8
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1answer
2k views

Picture of a camel's red blood cells

I'm an art student in need of a little help. I'm looking for microscopic pictures of camel's red blood cells, I need their shape for an art project. The pictures I find on Google seem a little ...
8
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1answer
1k views

Are Sloth tongues soft or rough?

Are Sloth tongues soft or rough? Dogs have soft tongues, while cats have rough tongues, so the feeling when they lick e.g. a human hand is quite different. So what about sloths? This question came ...
8
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2answers
2k views

Why do rabbits often have white hindquarters?

There are several species of herbivores that have a very visible white hindquarters: several kinds of deer, rabbits, antelopes, etc. Does the white fur serve a functional purpose, or is it purely ...
8
votes
1answer
780 views

What species is this mammal?

I saw a mammal that looked like a large squirrel. I haven't seen anything quite like it. Can you help me identify it? Squirrel-like, "hunched over" posture. It was too large to be an eastern squirrel&...
8
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5answers
10k views

Why do most mammals have long snouts?

It seems like most mammals, e.g. dogs, have long snouts. My pet dog's snout would seem to me like an evolutionary disadvantage, since her canine teeth are way out at the end of her jaw, which acts as ...
8
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3answers
8k views

Why have whales and dolphins not evolved to have gills? [duplicate]

It seems at first glance that it would be an evolutionary disadvantage for a sea creature to have to come up to the surface on a regular basis in order to breathe, so why are there animals (e.g. ...
8
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1answer
388 views

What is the reason for fear induced defecation?

I started to handle mice for my job and noticed that they tend to defecate and/or urinate when they are scared. The fear is induced by me, because I need a long time (due to inexperience) to grab the ...
8
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2answers
9k views

How do marine mammals control buoyancy?

Presumably, as a whale or seal dives, its lungs get compressed by the increasing water pressure, and it gets less buoyant. Under this model, for a given amount of air taken in at the surface, the ...
8
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1answer
106 views

Do individual mammal hairs absorb water?

In my look into the world of shaving I've seen claims that it is better to shave after a shower because the hairs will absorb water and soften, making the shave easier. Likewise, I've seen it claimed ...
8
votes
1answer
866 views

Squirrel nest construction

I've often wondered how squirrels -- specifically, eastern grey squirrels (Sciurus carolinensis) make their nests. Specifically, I've been curious about how they "weave" everything together to make ...
8
votes
1answer
382 views

Identify this vertebra

I was walking on the beach in New Jersey (U.S.), at about 40 degrees longitude, and found this bone. It's not a fish. The long process in the front is interesting. It is likely a C2 vertebra. I looked ...
7
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2answers
16k views

The number of nipples (breasts) a species has?

Only mammals have mammaries and mammary glands. What evolutionary factors determines the number of mammaries (nipples/teats/breasts) a species has? Is it always an even number?
7
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1answer
496 views

Biggest change in size from birth

Which mammal has the largest change in size from birth to fully grown percentage wise?
7
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2answers
638 views

Why does botulinum toxin seem to be more dangerous to humans than to other mammals?

Various mammals seem to get away with eating parts of carcasses that we would prefer to not even touch, and that we assume will make us sick. Because of that, I assume botulinum toxin is more ...
7
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2answers
16k 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?
7
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1answer
212 views

Why are recombination rates increasing in mammals?

I have recently become fascinated with an awesome topic in biology and evolution that I feel is rarely covered in biology courses. That is, rates of meiotic recombination, or the the amount that an ...
7
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2answers
103 views

What British bat is this?

What kind of bat is this? I saw it flying quickly between trees in Buckinghamshire, UK, at about 4pm in September (so about three hours before sunset). I think it might be a common noctule but I was ...
7
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1answer
256 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 ...
6
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2answers
4k views

What is the difference between the evolution of fins in whales and fish?

For a homework assignment I received the following question: Which statement best explains the evolution of fins in whales and fish? a. The common ancestor of whales and fish possessed genes for ...
6
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3answers
5k views

What is the fastest marine mammal?

When I did a research, most of the sources say that orca is one of the fastest. But I could not find a source that says it is actually the fastest. Some sources say that Dall's porpoises rival orcas ...
6
votes
1answer
825 views

Do any birds beside the family Columbidae (or any reptile or mammal) feed their young “Crop Milk”

Birds from the family Columbidae (e.g., doves and pigeons) produce a fatty, milk-like substance in their crop. The secretion is often referred to as "crop milk." They feed crop milk to their young ...
6
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4answers
39k views

Which organs do cats not eat on their prey?

My female cat is a very active hunter and brings me her prey daily. Except for shrews and birds, she always eats them entirely. This afternoon she brought me this: It was quite large (maybe between ...
6
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2answers
761 views

Are humans the only mammals that are known to display homosexuality?

REQUEST: In this post I do not refer to, nor do I encourage reference to, any ethical/moral/emotional aspects of homosexuality. So please don't start an pro/anti- LGBT campaign in the comments section....
6
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3answers
167 views

laboratory mice, nutrition, and humans

It seems that many nutrition experiments [directed at human diet] are carried on laboratory mice. Is there any justification that nutrition that is good or bad for laboratory mice will also be same ...
6
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1answer
3k views

Why does snow not stick to the fur of wolves and some breeds of dogs?

This question made me wonder, why for example wolves don't suffer from these "paw snowballs"? (...) but after a few miles on the trails in soft snow, he often develops snowballs between his paw ...