Shrimp swim by pulling their abdomen in toward their body quickly, states the Florida Fish and Wildlife Conservation Commission. The movement allows them to propel their body through the water, but because of their body's configuration, the motion causes them to swim backward. When done rapidly, it's also called lobstering.
The head and thorax are the two main parts that make up the body of the shrimp. Both parts are fused together to form the cephalothorax and a long, narrow abdomen. The cephalothorax is protected by a hard, thick shell called the carapace. The carapace surrounds the shrimp's gills, while the shrimp's rostrum, eyes, whiskers and legs emerge from the carapace. The rostrum is a beak-like protrusion that is an extension of the carapace. It is located at the front of the shrimp's head, and is typically used for attack, defense and as a stabilizer when the shrimp swims.
The rostrum also holds the shrimp's eye stalks. The eye stalks, which sit on either side of the rostrum, are compound eyes that have panoramic vision. The eyes are also good at detecting movement. The shrimp also has two pairs of antennae that extend from its head. One of the pairs of antennae is almost twice the length of the shrimp's body, while the other pair is extremely short. Each pair of antennae are equipped with sensors that allow the shrimp to feel, smell and taste by sampling the chemicals in the water. The long pair of antennae are also used to orient the shrimp to its surroundings and assess its prey.