Examples of groups of invertebrates are sponges, flatworms, roundworms,
segmented worms, mollusks and arthropods. Sponges have hollow tubes with
holes ...
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CLASSIFYING ANIMALS All animals are classified into groups according to things they have in common with other animals in that group. For example, animals with hair are not in the same groups as animals with feathers. The first major difference that separates groups of animals is whether or not they have backbones. Animals with backbones are called vertebrates. Animals without backbones are called invertebrates. Each of these groups is divided into even smaller groups. Examples of groups of invertebrates are sponges, flatworms, roundworms, segmented worms, mollusks and arthropods. Sponges have hollow tubes with holes called pores throughout their bodies. Flatworms, as the name suggests are flat worms! They have heads and tails but do not have true organs like stomachs, lungs, etc. Roundworms have round bodies, a digestive system and a nervous system. Segmented worms are more complex than flatworms and roundworms. Earthworms are one example of segmented worms. They have eyes, organ systems and even jaws. The group of invertebrates known as mollusks includes snails, clams and octopuses. Arthropods are the largest group of animal on earth. Insects, spiders, centipedes, millipedes, lobsters and crabs are all arthropods. Vertebrates groups include fish, amphibians, reptiles, birds and mammals. There are several different groups of fish; the simplest are known as agnathas. Agnathas do no not have bones in their skeletons like other vertebrates. Instead, these simple fish have skeletons made of cartilage and tough nerve cords that run down their backs. A second group of fish, known as osteichthys, has bones instead of cartilage. Amphibians are animals that begin their lives in the water and live on land as adults. This group includes frogs, toads and salamanders. In contrast, reptiles grow and develop outside water and live mostly on land. In fact, reptiles were the first animals to live on land. This group includes alligators, crocodiles, snakes and turtles. The group of vertebrates known as aves (birds) has feathers instead of fur or hair and walks on two hind legs. Most, but not all birds can fly. Mammals, the most complex group of animals, feed their young milk and have hair at some point in their lives. Mammals have relatively large brains for their size. Most live on land, but there are exceptions. For example, whales and dolphins are mammals that live in water. Copyright 2010 InstructorWeb www.instructorweb.com
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QUESTIONS 1. Animals are classified into different groups according to a. whether or not they have backbones. b. whether they have hair or feathers. c. whether or not they feed their young milk. d. All of the above 2. Invertebrates a. have backbones. b. do not have backbones. c. live only in water. d. is a group of animals that includes simple fish. 3. List six groups of invertebrates
4. The most complex group of worms are a. roundworms b. segmented worms c. flatworms d. snakes 5. List three types of mollusks.
6. The largest group of animals on earth is the ___________________ group. Copyright 2010 InstructorWeb www.instructorweb.com
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7. A major difference between amphibians and reptiles is a. amphibians live in water as adults; reptiles live on land as adults. b. reptiles are born in water; amphibians are born on land. c. reptiles live in water as adults; amphibians live on land as adults. d. amphibians are born in water; reptiles are born on land. 8. Name two characteristics of birds
9. Name two characteristics of mammals
10. Whales and dolphins are known as a. seafaring mammals. b. complex fish. c. aquatic mammals. d. All of the above
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ANSWERS 1. d 2. b 3. sponges, flatworms, roundworms, segmented worms, mollusks and arthropods 4. b 5. snails, clams and octopuses 6. arthropod 7. d 8. They have feathers and walk on two hind legs 9. They have hair at some point in their lives and feed their young milk 10. c
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