The difference between antlers and horns is that antlers are shed each year and are made of bone while horns are kept for life and are made of living tissue and bone with a sheath that is very similar to human finger nails.
10
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Dogs have been man's pet for over 14,000 years.
224
Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
132
A domestic cat can sprint at about 31 miles per hour.
274