All animals have a fundamentally similar skeletal structure.
See - in a dog's hind legs - the knees are the part that bends forward. The part that bends backward is the ankle. But unlike humans, a dog's ankles don't touch the ground. Effectivey, it walks on it's fingers - for greater speed.
In an elephant the two front knees are what would be wrists in humans.
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Duck quacks don't echo probably because ducks are social animals that live over a large area and echoing would make communication difficult. Wolf howls don't echo either.
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Of course a kangaroo can't go backwards. Most animals can't. Or rather they don't. Because they don't have to. Humans do because we are hyper and also do many other unnecessary things.
A cat will clean herself with paw and tongue after a dangerous
experience or when ishe has fought with another cat. This is believed to be
an attempt by the animal to soothe her nerves by doing something natural
and instinctive.
A rat can last longer without water than a camel can
All pet hamsters are descended from a single female wild golden hamster found with a litter of 12 young in Syria in 1930.
An ostrich's eye is bigger than its brain.
Camels have three eyelids to protect themselves from blowing sand.
Human tapeworms can grow up to 22.9m.
Pigs, walruses and light-colored horses can be sunburned.
Swans are the only birds with penises.
The bloodhound is the only animal whose evidence is admissible in an American court.
The expression "three dog night" originated with the Eskimos and means a very cold night - so cold that you have to bed down with three dogs to keep warm.
The giant squid is the largest creature without a backbone. It weighs up to 2.5 tons and grows up to 55 feet long. Each eye is a foot or more in diameter.
The Kiwi, national bird of New Zealand, can't fly. It lives in a hole in the ground, is almost blind, and lays only one egg each year. Despite this, it has survived for more than 70 million years.