The cat brain weighs about 30g.
167
A newborn Chinese water deer is so small, it can (almost) be held in the palm of a hand.
13
A banana slug can be 6-8 inches and their erect penis can be just as long. Also, their penises emerge from their heads. After sex, banana slugs eat each others penises.
17
The colossal squid has the largest eyes in the world.
4
A koi fish, named "Hanako", was owned by several individuals over many years and lived to be 226 years old, dying in 1977.
6
The oldest creature ever found was Ming the clam at an admirable 507 years old.
16
Pet dogs and elephants are the only animals that seem to instinctively understand human gesture.
14