Hot answers tagged

85 votes
Accepted

Why don't mammals have more than 4 limbs?

Number of legs in terrestrial vertebrates Not only do mammals have four legs but actually all terrestrial vertebrates (which include mammals) have four legs. There are slight exceptions though as ...
user avatar
  • 67.5k
56 votes
Accepted

Are there any non-mammalian species known that lactate?

Short answer Technically, only mammals lactate. To lactate means to produce milk from the mammaries to feed a baby or young animal. Milk, in turn, is defined as the secretions from mammary glands. ...
user avatar
  • 51k
36 votes
Accepted

Specific mechanism behind lethality of yellow coat color in mice

Really interesting question: The lethal yellow mutation (also abbreviated Ay) affects the agouti signalling protein which plays a major role in pigmentation. Heterozygous expression of it leads to the ...
user avatar
  • 49.1k
35 votes
Accepted

How and why did mammals go back to the oceans?

I'll focus on whales and dolphins (cetaceans) as you mention them by name and they are representative for other marine mammals such as seals or manatees. The evolution of cetaceans was one of the ...
user avatar
28 votes

Are there any non-mammalian species known that lactate?

Producing milk, per se, is a strictly mammalian phenomenon. There are functionally similar processes in non-mammals (e.g., 'crop milk', produced by some birds), but because these processes evolved ...
user avatar
  • 3,273
26 votes

Why is wombat scat (feces) shaped like cubes?

I'm almost certain that your question is based on the press that Patricia J Yang's research is receiving (e.g., here and here). Yang and her co-authors examined the structure and mechanics of some ...
user avatar
20 votes
Accepted

Can a person really die quickly from biting their tongue?

I know of an ER doctor who had a patient who removed (by biting and pulling) every last part of her tongue, she survived that (although, her ability to speak was probably shot). The stump of her ...
user avatar
  • 1,120
16 votes

Why don't mammals have more than 4 limbs?

I think I might interpret your question as asking, not just why don't mammals have more than four limbs, but why arthropods have more variety. Insects have six, but others have eight, ten, or more. ...
user avatar
16 votes
Accepted

Evolutionarily, why do male rats and horses lack nipples?

Male mice lack nipples too. Mice are frequently used for embryonic research as they are small and reproduce quickly. It is thought that male mice do develop nipples, but that they regress during ...
user avatar
  • 51k
15 votes
Accepted

Why haven't land animals evolved beyond urination?

It is probably true that toilets and other resting-ish area are always a great place to think about biology, I agree $\ddot \smile$. Why do we urinate? In short, urine contains the waste from our ...
user avatar
  • 67.5k
14 votes

Do male mammals other than humans have nipples?

Most mammalian males have nipples. The duck-billed platypus does not have nipples but you begin to see development of nipples in marsupials (Park and Lindberg 2004) like the opossum and kangaroo. ...
user avatar
14 votes
Accepted

Why do squirrels have twitchy bushy tails?

Tree jumping. The obvious answer is that having a balancing ballast is incredibly handy for some of the death defying jumps squirrels perform. The tail is needed for that. A big bushy tail might be a ...
user avatar
  • 11.2k
13 votes

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

I agree with you that the question is ambiguous, and also that the most sensible answer would be C. However, one could make a more or less reasonable argument in favor of several other answers, too. ...
user avatar
12 votes
Accepted

What species of fox is this?

This is a white morph red fox, not an arctic fox. As noted in the question, this fox has larger, more pointy ears than an arctic fox, and the second picture shows it to have a longer muzzle as well. ...
user avatar
  • 873
11 votes
Accepted

Mammal body density

Until someone has a better method to determine this, and I'm willing to go with idea of that this question is not answerable, I put forward the two likely forms of selection criteria: Which mammal ...
user avatar
  • 4,089
11 votes

What sea animal is this?

It's probably a dugong, based on the location, lack of a dorsal fin, split tail, lack of a blowhole, and narrowing of the snout. The prominent vertebral column looks unusual, but that might come from ...
user avatar
  • 35.1k
10 votes

Why don't mammals have more than 4 limbs?

The answer by Remi.B is excellent, I'll just attempt an explanation by way of gene networks: In genetics we see new genes "linking" to the older genome by regulation pathways and by being "fit" only ...
user avatar
  • 245
10 votes
Accepted

Biggest change in size from birth

@JM97 is correct. According to National Geographic >> The gestation period of a Red Kangaroo is 33 days and it's baby at birth weighs a mere 0.03 oz. To put it into a more precise perspective, on ...
user avatar
  • 1,268
10 votes
Accepted

Are Sloth tongues soft or rough?

Sloths have long, thick, sticky tongues covered in a carpet of tiny, rear-ward pointing spikes that they can pull leaves in with. So the tongues are quite different from human tongues and likely much ...
user avatar
  • 2,068
9 votes
Accepted

Why do rabbits often have white hindquarters?

Apparently the most noticeable research on this subject of a rabbit's white behind has been done by Dr Dirk Semmann of the University of Goettingen. He proposes that these spots actually confuse ...
user avatar
9 votes

Why don't mammals have more than 4 limbs?

Here is a more morphologic, less genetic answer: According to Sansom 2013, the 2 sets of paired appandages (shoulder and pelvic) was set in stone when agnathans transitioned into gnathostomes (ie. ...
user avatar
9 votes
Accepted

Do camels pose an environmental threat to kangaroos?

Feral camels have environmental, economic and cultural impacts in Australia's Northern Territory (Dept of Land Resource Management, Australia). In central Australia, camels feed on more than 80% of ...
user avatar
  • 51k
9 votes
Accepted

Are there examples of animals that live in groups, where all have the same role?

Yes, there are many examples. Those species are said to be gregarious. See below for examples. Level of sociality When it comes to social behaviour, it is common to categorize species into one of four ...
user avatar
  • 67.5k
9 votes

Why is wombat scat (feces) shaped like cubes?

On a more serious note than my comment, and as a supplement to theforestecologist's answer, it's worth pointing out that a cube with rounded corners and edges has larger surface area to volume ratio ...
user avatar
8 votes

How and why did mammals go back to the oceans?

How did they evolve from their original form to their superficially ichthyoid appearance today? This is an example of convergent evolution. Fish appear as they do (streamlined body shape, wide tail, ...
user avatar
  • 181
8 votes
Accepted

How do other primates treat their fingernails?

Both. Many primates bite their nails. Some do not. It's not species specific. Chimpanzees, for example, usually bite their nails; some prefer to leave them alone. They do grow continuously, and nails ...
user avatar
8 votes
Accepted

Mystery rodent in Winnipeg

That is a Franklin's Ground Squirrel Winnipeg is part of its range: Have a look at a gallery of such photos here: https://inaturalist.ca/taxa/179937-Poliocitellus-franklinii/browse_photos
user avatar
  • 1,506
7 votes
Accepted

Do mammals and birds have a common warm-blooded ancestor?

Welcome to Biology.SE. Did you say warm-blooded? The term warm-blood is very unclear. The correct terms are endo-, exo-, poikilo- and homeo- therm. In short&...
user avatar
  • 67.5k
7 votes
Accepted

Are all non-breeding naked mole rats the same sex?

Naked mole rat colonies contain individuals of both sexes, with one breeding female and one to three breeding males, and the rest non-breeding individuals of both sexes. The other individuals in the ...
user avatar
  • 35.1k

Only top scored, non community-wiki answers of a minimum length are eligible