Some lizards, in which the tail is a major storage organ for accumulating reserves, will return to a dropped tail after the threat has passed, and will eat it to recover part of the sacrificed supplies.
13
Some older/less efficient worker termites will develop 'backpacks' of toxic chemicals that explode when the termite is threatened. They are essentially used as suicide bombers when the colony is being attacked.
8
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
It has been estimated that a bite from a grizzly bear can crush a bowling ball.
11
Blue whale arteries are large enough for humans to swim through and their hearts are the size of cars.
12