If you've ever passed by a field of horses at night, you've probably noticed that they rarely lie down to sleep.So why do these mammals sleep standing up?The answer is one of survival: Horses slumber while standing to balance their need for sleep against the ever-looming threat of predators.Horses come from a long line of prey animals in the family Equidae, and sleeping on their hooves is an adaptation against predation.
[
add
]
[
|
|
...
]