Goldfish were originally green. The Chinese bred them to be many different colors. Gold stuck.Sea urchins reproduced by splitting themselves in two. Goldfish have a memory span of three seconds.The skin of a tiger shark is 10 times as strong as ox hide.Oysters can change gender according to the temperature of the water they live in.A group of jellyfish is known as a “”smack.””Jellyfish are 99 percent water.Fish with forked tails swim faster than fish with straight tails.The dolphins that live in the Amazon River are pink.