A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
The colossal squid has the largest eyes in the world.
4
Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
132
Denmark has twice as many pigs as there are people.
66
Only 3% of bird species have penises.
0
Blue whale arteries are large enough for humans to swim through and their hearts are the size of cars.
12
A cow produces around 200,000 glasses of milk in her lifetime.
373