An alligator can go through 2,000 to 3,000 teeth in a lifetime.
268
The seahorse is the only fish to have a neck.
12
Sheep, goats, octopuses, and toads have rectangular pupils.
7
Cows as they are today never existed in the wild and were domesticated from aurochs some 10,500 years ago.
6
When Washoe, the first chimp to use sign language, was told that her caretaker's baby had died, she signed "CRY."
20