85
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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 ...
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56
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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. ...
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36
votes
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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 ...
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35
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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 ...
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28
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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 ...
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26
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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 ...
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20
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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 ...
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16
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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.
...
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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 ...
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15
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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 ...
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14
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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. ...
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14
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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 ...
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13
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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.
...
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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.
...
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11
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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 ...
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11
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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 ...
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10
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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 ...
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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 ...
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10
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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 ...
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9
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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 ...
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9
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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. ...
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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 ...
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9
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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 ...
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9
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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 ...
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8
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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, ...
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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 ...
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8
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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
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7
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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&...
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7
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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 ...
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