Invertebrate Animals 4.1 Most animals are invertebrates. 4.2 CHAPTER NEW CHAPTER Invertebrate Animals the BIG idea Invertebrate animals have a variety of body plans and adaptations. 4.1 Most animals are invertebrates. 4.2 Cnidarians and worms have different body plans. 4.3 Most mollusks have shells, and echinoderms have spiny skeletons. 4.4 Arthropods have exoskeletons and joints. CHAPTER OUTLINE CHAPTER RESOURCES

4.1 Most animals are invertebrates. Invertebrates are a diverse group of animals. Species of invertebrates live in almost every environment. invertebrate sponge sessile larva CHAPTER RESOURCES Sponges are simple invertebrates that have several types of specialized cells. SECTION OUTLINE

4.1 invertebrate Most animals are invertebrates. sponge An animal that has no backbone. sessile larva CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.1 sponge Most animals are invertebrates. A simple multicellular invertebrate animal that lives attached to one place and filters food from water. sessile larva CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.1 sessile Most animals are invertebrates. sponge The quality of being attached to one spot; not free-moving. sessile larva CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.1 larva Most animals are invertebrates. sponge A free-living early form of a developing organism that is very different from its adult form. sessile larva CHAPTER RESOURCES KEY CONCEPT SUMMARY

Cnidarians and worms have different body plans. 4.2 Cnidarians and worms have different body plans. cnidarian Cnidarians have simple bodies with specialized cells and tissues. Most worms have organs and complex body systems. tentacle mobile CHAPTER RESOURCES SECTION OUTLINE

4.2 cnidarian Cnidarians and worms have different body plans. tentacle An invertebrate animal such as a jellyfish that has a body with radial symmetry, tentacles with stinging cells, and a central internal cavity. mobile CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.2 tentacle Cnidarians and worms have different body plans. A long, slender, flexible extension of the body of certain animals, such as jellyfish. Tentacles are used to touch, move, or hold. mobile CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.2 mobile Cnidarians and worms have different body plans. tentacle Able to move from place to place. mobile CHAPTER RESOURCES KEY CONCEPT SUMMARY

Most mollusks have shells, and echinoderms have spiny skeletons. 4.3 Most mollusks have shells, and echinoderms have spiny skeletons. Mollusks include bivalves, gastropods, and cephalopods. Echinoderms have a water vascular system and tube feet. mollusk gill lung echinoderm VISUALIZATION Watch how different cephalopods move. CHAPTER RESOURCES SECTION OUTLINE

4.3 Most mollusks have shells, and echinoderms have spiny skeletons. mollusk mollusk gill An invertebrate animal with a soft body, a muscular foot, and a mantle. Many mollusks have a hard outer shell. lung echinoderm CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.3 Most mollusks have shells, and echinoderms have spiny skeletons. mollusk gill gill A respiratory organ that filters oxygen dissolved in water. lung echinoderm CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.3 Most mollusks have shells, and echinoderms have spiny skeletons. mollusk lung gill A respiratory organ that absorbs oxygen from the air. lung echinoderm CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.3 Most mollusks have shells, and echinoderms have spiny skeletons. mollusk echinoderm gill An invertebrate sea animal with a spiny skeleton, a water vascular system, and tube feet. lung echinoderm CHAPTER RESOURCES KEY CONCEPT SUMMARY

Arthropods have exoskeletons and joints. 4.4 Arthropods have exoskeletons and joints. crustaceans, and arachnids, Arthropods, which include insects, are the most abundant and diverse group of animals. arthropod exoskeleton • Includes shrimp, crabs, lobsters,barnacles, and pill bugs • Number of body segments and pairs of legs varies, 2 pairs of antennae • Most live in water; some live on land Crustaceans • Includes beetles, bees, wasps, ants, butterflies, moths, and grasshoppers • 3 pairs of legs, 3 body segments, 1 pair of antennae • Most live on land Insects molting insect metamorphosis • Includes spiders, ticks, mites, and scorpions • 4 pairs of legs, 2 body segments, no antennae • Most live on land Arachnids CHAPTER RESOURCES SECTION OUTLINE

4.4 arthropod Arthropods have exoskeletons and joints. An invertebrate animal with an exoskeleton, a segmented body, and jointed legs. molting insect metamorphosis CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.4 exoskeleton Arthropods have exoskeletons and joints. The strong, flexible outer covering of some invertebrate animals, such as arthropods. molting insect metamorphosis CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.4 molting Arthropods have exoskeletons and joints. The process of an arthropod shedding its exoskeleton to allow for growth. molting insect metamorphosis CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.4 insect Arthropods have exoskeletons and joints. An arthropod with three body segments, six legs, two antennae, and compound eyes. molting insect metamorphosis CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.4 metamorphosis Arthropods have exoskeletons and joints. The transformation of an animal from its larval form into its adult form. molting insect metamorphosis CHAPTER RESOURCES KEY CONCEPT SUMMARY

4.1 Most animals are invertebrates. I. Most animals are invertebrates. A. Invertebrates are a diverse group of organisms. sponge B. Sponges are simple animals. sessile 1. Specialized Cells larva 2. Reproduction CHAPTER RESOURCES KEY CONCEPT SUMMARY

Cnidarians and worms have different body plans. 4.2 Cnidarians and worms have different body plans. II. Cnidarians and worms have different body plans. cnidarian A. Cnidarians have simple body systems. tentacle 1. Tissues and Body Systems mobile 2. Reproduction B. Animals have different body plans. C. Most worms have complex body systems. 1. Segmented Worms 2. Flatworms and Roundworms CHAPTER RESOURCES KEY CONCEPT SUMMARY

Most mollusks have shells, and echinoderms have spiny skeletons. 4.3 Most mollusks have shells, and echinoderms have spiny skeletons. III. Most mollusks have shells, and echinoderms have spiny skeletons. mollusk A. Mollusks are soft-bodied animals. gill 1. Bivalves lung 2. Gastropods echinoderm 3. Cephalopods B. Mollusks show a range of adaptations. C. Echinoderms have unusual adaptations. 1. Spines and Skeletons 2. Water Vascular System and Tube Feet CHAPTER RESOURCES KEY CONCEPT SUMMARY

Arthropods have exoskeletons and joints. 4.4 Arthropods have exoskeletons and joints. IV. Arthropods have exoskeletons and joints. arthropod A. Most invertebrates are arthropods. exoskeleton 1. Exoskeletons and Jointed Parts molting 2. Complex Body Systems insect B. Insects are six-legged arthropods. metamorphosis C. Crustaceans live in water and on land. D. Arachnids are eight-legged arthropods. E. Millipedes and centipedes are arthropods. CHAPTER RESOURCES KEY CONCEPT SUMMARY

Image Gallery Click on the icons to see a larger image or animation. CHAPTER HOME Image Gallery Click on the icons to see a larger image or animation. VISUALIZATION Watch how different cephalopods move.

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