II.

Range and Habitat

Shrimp are found in all the world’s oceans, as well as in freshwater lakes and streams. In the oceans, some open-water species live at depths around 5 km (3 mi), but most are found closer to the surface. To avoid predators, most open-water shrimp carry out daily migrations. They feed near the water’s surface at night but spend the daytime hiding in the murky depths of the ocean, about 200 m (660 ft) down.

Most of the shrimp caught as human food are bottom-dwellers that live on shallow seabeds. These species are often scavengers, feeding on remains of dead animals. Scavenging shrimp are also common in eel-grass beds that grow close to the shore. In the western Atlantic, the Sargassum shrimp, also known as the brown glass shrimp, is one of the few species that lives in a floating habitat—the clumps of seaweed that drift in the Sargasso Sea.

Rather than venturing out into the open, some shrimp spend their lives hidden away. Many shelter under rocks or in coral crevices. Others live in caves, where they feed on dead remains. Burrowing shrimp excavate homes in soft sediment. In Southeast Asia, one kind of burrowing shrimp can cause problems in rice fields, which are submerged underwater. The digging action of burrowing shrimp creates muddy waters that block photosynthesis and decrease the oxygen levels in the water, thereby smothering young rice shoots.