Classifying Animals Lesson 3 Let’s brainstorm different animals that we have seen. With your partner, write down as many different animals you can think of in one minute. • Now that you’ve brainstormed different animals let’s classify each one as a vertebrate or invertebrate. Partners, write beside each animal “V” for vertebrate or a “I” for invertebrate. To which group of animals do you belong? • Vertebrates, mammals • What are some things that we can do, but animals can’t do? • Examples: We can read, write, talk, and think. Let’s read “Look and Wonder” on p.48. • How do you determine whether an organism is an animal? • You can look at characteristics such as how it gets food, how it reproduces, and whether it moves. Let’s read pages 50-51. • What characteristic sets invertebrates apart from vertebrates? • The lack of a backbone. • Where do most simple invertebrates live? • In water or moist environments. Look at the images on pgs. 50-51. • What is unique about sponges and what kind of symmetry do they have? • Sponges are the only animals without real tissues or organs. They are asymmetrical. asymmetrical • • • • • • • • • Let’s look closely at this word. What is the base word in asymmetrical? Symmetry What does the word symmetry mean? It means “the same on either side of a dividing line”. The end of this word ical means “having symmetry”. What is the prefix? The prefix a means “not”. So, asymmetrical means “not having symmetry”. radial symmetry • Radial means “rod or spoke of a wheel”. • Radial symmetry means “wheel-like symmetry”. bilateral symmetry • Bilateral means “a side”. • bi means “two”. • Bilateral symmetry means “two-sided symmetry”. Animal diversity • Often, people think of animals as being large, living on land, having four legs, and furry. This is a misconception. There is a tremendous diversity among animals- from very simple sponges to mammals. “Quick Check” questions p. 51 • What are some simple invertebrates? • Sponges, cnidarians, and worms. • What characteristics do scientists use to classify cnidarians? • All cnidarians have stinging cells. They also have radial symmetry. Let’s read pages 52-53. • Complex invertebrates- the term complex means “having many parts”. These invertebrates have many recognizable body parts and organs. They also can grow larger than simple invertebrates. What are three phyla of complex invertebrates? • mollusks • echinoderms • arthropods Mollusks • • • • Muscular foot or tentacles An example is a snail. What type of symmetry do mollusks have? Mollusks have bilateral symmetry. Echinoderms • Many tube feet • An example is a sea star. • What type of symmetry do echinoderms have? • Echinoderms usually have radial symmetry. Arthropods • • • • Exoskeleton An example is a crab. What type of symmetry do they have? Bilateral symmetry Look at the images on pgs. 52-53. • How is the snail’s shell formed? • The mantle secretes the shell. • Why can you often see a sea star’s skeleton on the outside? • Spines from the skeleton often project through their skin. • Where is the crab’s skeleton? • On the outside of its body. “Read the Photo” p. 53 • What do arthropods have in common? • Both arthropods have jointed legs and segmented bodies. “Quick Check” questions p. 53. • What body parts do arthropods have that echinoderms do not have? • Head, eyes, legs • The smaller the animal, the simpler the animal. Is this statement generally true? • No. Most insects, for example, are smaller than mollusks but not simple at all. Let’s read pgs. 54-55. • What three characteristics do vertebrates have in common? • They have backbones, bilateral symmetry, and a skeleton inside their bodies. • Why do reptiles have to sun themselves? • Reptiles sun themselves to stay warm because they are cold-blooded and cannot automatically keep their body temperature steady. What are the three classes of fish? • Jawless fish • cartilaginous fish • bony fish “Read a Photo” p. 55. • How are birds and reptiles different? • Birds have feathers. Reptiles have dry skin and scales. With a partner, answer the “Quick Check” questions on p. 55 (3 min.) • What are characteristics of vertebrates? • Vertebrates have backbones, bilateral symmetry, and skeletons inside their bodies. • Why do many reptiles hide at night and stay completely inactive? • Since reptiles rely on environmental heat, they cannot get warm enough at night to be active. Let’s read p. 56. • What characteristics make humans mammals? • We have hair, large brains, and nourish our young with milk. • What does it mean to say that birds and mammals are “warm-blooded”? • They generate their own body heat. “Quick Check” questions p. 56 • What characteristics are shared by all mammals? • All mammals have hair, feed their young milk, have large brains, and are warm-blooded. • How do marsupials benefit from carrying their young in a pouch? • Marsupials protect their young by carrying them in a pouch. Choose the BEST answer. • Which animal exhibits radial symmetry? A. Worm B. Jellyfish C. Sponge D. Mollusk Choose the BEST answer. • How are annelid worms, such as earthworms, different from other worms? A. They have a digestive system B. Their bodies are divided into segments. C. Their bodies have bilateral symmetry. D. They live inside the bodies of other animals. Choose the BEST answer. • Which structure allows bony fish to easily go up or down in water? A. Jaw B. Gills C. Cartilage D. Swim bladder Choose the BEST answer. • Which animal is warm-blooded? A. Eagle B. Shark C. Salmon D. Bullfrog A koala and a giraffe look very different, but they are both animals. Give an example of how these organisms are alike and an example of how they are different. • Both have hair. • They are different in that the koala has a pouch to carry its young and the giraffe does not have a pouch.