Insects including butterflies, beetles, ants, bees, moths, and flies, develop through complete metamorphosis.
Four stages of development
A fertilized egg hatches into worm-like larva stage. During this time it eats and grows before forming a shelter called a cocoon or chrysalis. Then goes into a resting stage called the pupa. The larva inside changes and develops into an adult by a process that is not yet understood.
Spiders, scorpions, mites, and ticks are arachnids. Arachnids are arthropods with two body regions, a head-chest region called the cephalothoraxes and an abdomen. They have eight legs. They kill prey with poison glands, stingers, or fangs.
Spiders use fangs to inject poison into the prey.
Tricks and mites are arachnids that are parasites. Mites are very tiny and are usually found in the dust on the floors and on beddings. Mites also can be found in the follicles of human eyelashes.
Scorpions have a sharp stinger at the end of the abdomen that contains poison.
Centipedes and millipedes look like worms but you know they are not because worms do not have legs. They make up two classes of arthropods. They have long bodies with many segments, exoskeleton, jointed legs, antennae, and simple eyes. They live on land and reproduce sexually.
Centipedes have one pair of jointed legs per segment. They feed on snails, slugs, and worms. Their bites are painful on humans.
Millipedes have two pairs of legs per segment. They feed on plants. They do not move as fast as centipedes.
Crabs, crayfish, lobsters, shrimp, barnacles, pill bugs, and water fleas belong to the class Crustacean. They have one or two antennas and jaws called mandible used for crushing food. They live in water except for pill bugs in which they live on land that is moist. They have five pairs of legs. The first pair of legs are claws that catch and hold food. The other four pairs are walking legs.