A shrimp's heart is located in its head. There are around 2,000 species of shrimp in the world.
Shrimp are unique in that they swim backward in a motion that is achieved by quickly flexing their tails and abdomens. Shrimp live in the ocean in both deep and shallow water, and they are also bountiful in some freshwater lakes and streams.
The average-sized shrimp measures 1.5 to 3 inches, although some individuals have been observed reaching lengths up to 8 inches. Larger shrimp are referred to as prawns. There are some species of shrimp that are commercially grown for food, although much of the shrimp sold in supermarkets is caught by shrimpers.