Cool CrustaceansWe love crustaceans, one of the big groups of arthropods. They have crabs, lobsters, shrimp, and barnacles. You'll find all of them living in the water or in very wet environments. One example of a crustacean that lives out of the water is a pillbug or sow bug. That's right. Pillbugs are related to lobsters.
What makes crustaceans similar to other arthropods? They have special legs that are jointed. They usually have several legs, more than the four that mammals have. They also have advanced nervous systems and groups of neurons that work to help the organism hunt, move around, and find a mate. Crustaceans can also learn. They can learn new behaviors and adapt to new situations.
We've Got Crabs!They're right on the dinner table. We also eat lobsters and shrimp. Crustaceans are a big source of food for many animals. What do they eat? Stuff on the bottom of the ocean. Stuff that's floating around the ocean. Even though you might think of their big claws, crabs and lobsters don't run around and hunt down food. It's a lot easier to find a dead fish and pick it apart. It's even easier to be a barnacle (which doesn't move once it becomes an adult) and wave around a filter to grabs pieces of food from the water. Remember, intimidating looks don't always mean aggressive animals. But don't go and put your finger in those claws, they will break your finger as a defensive action.
Thick ExoskeletonsWhat else makes crustaceans so special? Their exoskeleton is very special. Some of the parts have actually fused together to form one piece. If you look very closely, you will see the places where they meet. They have something called a cephalothorax that is actually several sections of exoskeleton fused together. They have also developed a shield for their head. An insect head is sitting out there and could be bitten off. Crustaceans have developed a shield to protect their eyes and head area. Some of them don't even have obvious heads. One example is a crab that has one big shell protecting its entire body.
Science Nation: Crabs Put Pinch on Marshlands (US-NSF Video)