Chapter 10 Section 2 Arthropods

Characteristics of Arthropods Four major groups Crustaceans Arachnids Centipedes and Millipedes Insects Shared characteristics Invertebrates External skeleton Segmented body Jointed attachments called appendages (wings, mouthparts, legs)

Outer Skeleton Exoskeleton When an arthropod grows… Waxy covering, or outer skeleton Protects and helps prevent evaporation of water (adaptation) When an arthropod grows… Molting occurs Molting: process of shedding an outgrown exoskeleton New exoskeleton is soft for a little while, less protection

Segmented Body Bodies made up of many identical-looking segments Easily seen on millipedes and centipedes Normally three sections Head, midsection, and a hind section

Jointed Appendages Your fingers! Give the animal flexibility and enable it to move Use legs to move, catch prey, defending against predators Use antenna, has sense organs for smelling, tasting, and touching

Crustaceans Shrimp, crabs, crayfish, lobsters Thrive in freshwater lakes and rivers Two or three body sections Five or more pairs of legs Two pairs of antennae Get oxygen from gills Life Cycle Crustaceans begin their lives as microscopic, swimming larva and develop into adults by metamorphosis (a process by which an animal’s body undergoes dramatic changes in form during life cycle)

Arachnids Spiders, Mites, Scorpions, Ticks Two body sections (first body section=head and midsection, hind section=abdomen) Four pairs of legs No antennae

Arachnids All spiders are predators, eat insects MITES SCORPIONS TICKS All spiders are predators, eat insects Hollow fangs, inject venom into prey Rarely bite people Another name is a chigger Parasites Live in hot climates Active at night Stinger at end of abdomen Live on the outside of a hosts body

Centipedes and Millipedes Have two body sections and many pairs of legs Centipedes One pairs of legs attached to each segment Sometimes more than 100 segments Predators that inject venom into prey Millipede Two pairs of legs attached to each segment Sometimes more than 80 segments Scavengers