Barnacles live only in the sea. They are related to crabs and lobsters. Barnacles stick themselves to a surface and live there in the same place for their entire adult lives. You usually see them on the beach stuck to rocks, or stuck to the bottom of boats. They eat small sea creatures that drift past them in the water.
Scientific name: crustaceans of the infraorder brachyura
Crabs are found all over the world around water, both in the sea and in fresh water. They can range in size from a few centimetres wide to up to four metres wide. They have a very thick outside shell, and people catch them to eat.
Crayfish look like a small lobster and are found in fresh water like lakes, streams and rivers. There are many different varieties of crayfish. Crayfish are also called crawfish, crawdad or yabbies. They can be eaten in the same way as lobsters.
Crustaceans are a kind of arthropod that include crabs, lobsters, krill and barnacles. Most crustaceans live in the sea, but some like the woodlouse live on land.
Hermit crabs are not actually true crabs, but are distantly related crustaceans. Hermit crabs don't have a shell of their own, so they need to find the discarded shell from another creature to wear. As they grow, they have to find another shell to replace their old one. Hermit crabs are found all over the world, and many people keep them as pets.
Scientific name: order: euphausiacea
Krill are small, shrimp-like crustaceans that live in huge numbers in the sea. They are food for a very large number of different sea creatures, including some whales. Krill are near the bottom of the food chain in the sea.
Scientific name: family: nephropidae
Lobsters are a group of sea creatures related to the crab. They have no skeleton but are covered in a hard shell. Lobsters are caught to eat, and are considered a luxury food. They are usually cooked simply by dropping them in boiling water.
Scientific name: infraorder: caridea
A shrimp, also called a prawn in many countries, is a sea creature that usually grows to a few inches long. They are a very popular food, and can be eaten boiled, fried, barbequed and many other ways, plain or with a sauce. They are quite often cooked whole and you have to remove the head, legs and other inedible parts yourself.
Scientific name: porcellio scaber
The woodlouse (also called an armadillo bug, carpenter, cheeselog, doodlebug, pill bug, roly-poly, chuggypig, slater beetle, sow bug or gramersow) is a type of crustacean, and is related to the crab and lobster. They eat dead plants and fallen leaves. Woodlice breathe through gills like fish, which is why you often find them in damp places. Some types of woodlouse can roll themselves up into a tight ball.