Transcript File
Science Unit A – Chapter 1 Comparing Living Things Lesson 3: How Are Animals Classified? Animals Without Backbones • Animals that have no backbones are called invertebrates. • Invertebrates are many-celled organisms. • Sponges, jellyfish, worms, sea stars, mollusks, and arthropods are all examples of invertebrates. Sponges • Look more like plants than animals • Live underwater • Do not move -- They attach themselves to rocks or other objects in the water. • Trap and eat tiny organisms that float in the water that flows in and out of their hollow bodies Jellyfish • Have hollow bodies that water flows in and out of • Have a mouth surrounded by tentacles • Tentacles are used to capture prey. Mollusks • Have soft bodies • Bodies are protected by one or two shells. • We eat many of these. • Snails, oysters, and clams are examples of mollusks. Sea Stars • Live on the ocean floor • Use suction cups on their underside to stay in place and to pry open shells • Tough skin and spines protect them from enemies. Arthropods • This groups contains more than 80% of all animal species! • Lobsters, crabs, spiders, centipedes, millipedes, and insects (70%) are examples. • Have a stiff outer covering called an exoskeleton for protection. • The exoskeleton has joints that allow movement. Worms • Live mostly underground • Eat the remains of dead plants and animals • Have narrow, tubelike bodies • Flatworms have flat bodies. • Roundworms look like tiny snakes with no heads. • Earthworms are examples of segmented worms. Animals With Backbones • Animals that have backbones are called vertebrates. • There are five groups of vertebrates. 1. Fish 2. Amphibians 3. Reptiles 4. Birds 5. Mammals Fish • Live their whole lives in the water • Use tails and fins to move • Take in oxygen from the water through their gills • Lay eggs in water • Range in size from 1 inch to 50 feet long Amphibians • Lay eggs in water • Live part of their lives in water (with gills) and part on land (with lungs) • Usually stay near water • Frogs and salamanders are examples. Reptiles • Breathe with lungs their whole lives • Bodies are covered with tough, dry scales. • Most lay leathery-shelled eggs on land. • Lizards, snakes, turtles, alligators, and crocodiles are examples. Birds • Breathe air all their lives • Lay hard-shelled eggs on land • Hollow bones make their bodies light. • Bodies are covered with feathers. • Not all birds fly! Mammals • Have hair or fur on their bodies • Breathe through lungs all their lives • Mammals are the only animals that feed their young with milk produced by the mother. • Mammals give birth to live young. • Live on land, in water, and in the air Questions 1. What are invertebrates? 2. What are vertebrates?