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
The oldest known animal in the world was 'Ming' the 405 year old clam, discovered in 2007.
492
There is a sea snail that wears a suit of iron plated armor. It is the only known animal to use iron sulphide as skeletal material.
9
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23