Arthropods (“Jointed Foot”) make up the largest phylum of animal in the animal kingdom.
-centipedes and millipedes
Appendages are structures that grow from the body.
Exoskeletons are the arthropods external covering.
Supports and protects the body
Made of chitin
Molting is a process in which the old exoskeleton is shed and replaced by a new one.
Takes awhile to harden
Animal is not protected from its predators
Insects are the largest group of complex invertebrates.
There are more than 700,000 classified insects and still more are being discovered.
Insect Body Plan
Insects have 3 body regions
-The head has a pair of antennae
Insects are the only invertebrates that are able to fly
Insects have a open circulatory system.
Insects have openings called spiracles on the abdomen and thorax through which air enters and waste gases are expelled
Metamorphosis is when species of insects and animals hatch from a fertilized egg, go through a series of changes in body form to become adults.
There are two kinds of metamorphosis - Complete
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.
Insects including grasshoppers, silverfish, lice, and crickets is developed through incomplete metamorphosis.
The three stages of incomplete metamorphosis
The fertilized egg hatches into a nymph that looks like a small adult but does not yet have wings. The nymph molts several times before reaching the adult stage.
Exoskeleton, wings, and jointed appendages allow insects to live on land and to fly.
Arachnids, centipedes, millipedes, and crustaceans are other classes of arthropods.
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
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.