Critters of the Sea Crustaceans encompass a vast array of hard-shelled, mostly aquatic animals such as crabs, lobster, shrimp, prawns, krill, and barnacles. Although woodlice and a few crab species live on land and in freshwater, most crustaceans live in the ocean. They can be found in every ocean habitat from prawns and shrimp swimming freely in the open ocean to barnacles attached to rocks, piers, and even the sides of ships. They will be encountered at every depth from krill, floating near the water’s surface to shrimp-like creatures in the ocean’s deepest trenches. There are 50,000 known species of crustaceans, with more discovered every year. Scuba diving with crustaceans is always exciting, but there are some specific species divers seek out throughout the world. Mantis shrimp are a photographer’s dream; you can dive with the illusive mantis shrimp in tropical regions of the Pacific and Indian oceans. Some divers seek out areas to go lobster hunting throughout the year in places like the Caribbean, while others search for fascinating crab species like the most massive crab in the world, the Tasmanian Giant crab in Southern Australia. Click here to learn more about where you can dive with different types of crustaceans around the world. © Shutterstock-Shane GrossShrimpThere are nearly as many types of shrimp as there are ways to cook them, with approximately 2,000 different species.Learn more © iStock-Michael ZeiglerCrabWith over 6500 different species, crabs are one of the most varied aquatic dwellers in the world.Learn more