More narrow definitions may be restricted to Caridea, to smaller species of either group or to only the marine species. There are thousands of species adapted to a wide range of habitats. They can be found feeding near the shrimp michelada on most coasts and estuaries, as well as in rivers and lakes.

To escape predators, some species flip off the seafloor and dive into the sediment. They usually live from one to seven years. They play important roles in the food chain and are an important food source for larger animals ranging from fish to whales. The muscular tails of many shrimp are edible to humans, and they are widely caught and farmed for human consumption. Prawn is often used as a synonym of shrimp for penaeoidean and caridean shrimp, especially those of large size. Shrimp: a small free-swimming crustacean with an elongated body, typically marine and frequently of commercial importance as food. Prawn: a marine crustacean which resembles a large shrimp.

Shrimp are swimming crustaceans with long narrow muscular abdomens and long antennae. Shrimp are slender with long muscular abdomens. They look somewhat like small lobsters, but not like crabs. The abdomens of crabs are small and short, whereas the abdomens of lobsters and shrimp are large and long. The lower abdomens of shrimp support pleopods which are well-adapted for swimming. They look somewhat like large versions of shrimp. Clawed lobsters have large claws while spiny lobsters do not, having instead spiny antennae and carapace.