Chapter 17 Section 4 notes

Characteristics of Arthropods: More than 1 million species Largest and most diverse group of animals Jointed appendages (structures such as claws, legs, & antennae that grow from the body) Exoskeleton-protects and supports the body and reduces water loss

Arthropods cont…… As the animal grows, the exoskeleton must be shed…called molting Bilateral symmetry 7. Segmented bodies

Types of Arthropods: Insects – make up the largest group of complex invertebrates - have 3 body regions (head-thorax-abdomen) - open circulatory system

(2) Arachnids – predators - 2 body regions (cephalothorax & abdomen) - 4 pairs of legs (8 total) - EX….spiders, ticks, mites, & scorpions

(3) Centipedes & Millipedes - long, thin, segmented animals - centipedes (predators) have pairs of jointed legs attached to each segment - millipedes (eat plants) have 2 pairs of jointed legs attached to each segment

(4) Crustaceans usually have 2 pairs of antennae - 3 types of chewing appendages - 5 pairs of legs - swimmerets – force water over the feathery gills where carbon dioxide is exchanged for oxygen in the water - EX….crabs, crayfish, lobsters, shrimp, barnacles, etc….

Echinoderms Have radial symmetry Have spines of various lengths that cover the outside of their bodies Some are predators Some are filter feeders Some feed on decaying matter Water-vascular system (network of water-filled canals & thousands of tube feet…work as suction cups to move or capture prey) Regenerate lost or damaged limbs EX……..sea stars (starfish), sand dollars, sea urchins