Insects don't have internal bones the way people do: their hard supporting structures are all on the outside, and need to be rebuilt as the insect grows.
When in between exoskeletons, blue crabs rely on an inner hydrostatic skeleton to move about.
Have you ever seen crabs crawling around on the beach? They're called limlus polyphemus, commonly known as a horseshoe crab.
Did you know that three hundred million years ago the earth was swarming with giant insects? How did insects get so small today?
A coral reef could be said to be both animal and plant.
Though most true bugs eat plant sap, some feed on animals. One such true bug is the assassin bug, which feeds on fellow insects.
What's a fly doing in Antarctica? Find out on this Moment of Science.
Learn about the differences between soft-shelled and hard-shelled crabs on this Moment of Science.