10 Invertebrates-Mid

Invertebrates Written by Brooke Bessesen

Introduction Invertebrates are "spineless" animals. That means they have no backbone, or spine. Run your hand down the center of your back. Do you feel those bumps? The bones of your spine are called vertebrae (VER-tuh-bray). Animals with a spine are called vertebrates. Humans are vertebrates But most animals are invertebrates. They don't have a spine.

What Do Invertebrates Have in Common? Invertebrates come in many shapes, yet they have a lot in common. You already know they have no spine, but they share other traits, too: Like all animals, invertebrates have more than one cell. Most invertebrates can move from one place to another. Others stay in one place but move their body parts. Invertebrates don't have lungs. They get oxygen through tiny holes on their body or through gills.

Most invertebrates have symmetry. That means the two sides of their body look alike. Some have a center point. Any line through that center will make matching halves. Invertebrates can't make their own body heat. They are cold-blooded. Most invertebrates produce young with sperm from males and eggs from females. Invertebrates must eat food for energy. In this book, you will learn about some groups of invertebrates and how they move and eat. You will also learn a few other traits of each group.

Classifying Invertebrates Invertebrates have traits in common, but they have many differences, too. A fruit fly is smaller than a grain of rice. A giant squid can be 17 meters (55 ft.) long, with eyes bigger than basketballs! Centipedes eat worms, but butterflies drink nectar. A mosquito flies in the air A crab crawls on the seafloor. Earth has more than a million kinds of invertebrates Imagine the variety! Word Wise Each type of animal has a common name. and a scientific name Apis mellifera is the scientific name for a honeybee.

Animals look and act in different ways. Scientists classify them by common traits. They classify animals as either vertebrates or invertebrates. Each group has many smaller groups. As you read about these groups, think about why certain invertebrates are placed in the same group. Vertebrates Mammals Birds Reptiles Amphibians Fish Invertebrates Poriferans sponges Cnidarians sea jellies corals sea anemones Echinoderms sea stars sea urchins sand dollars Mollusks octopuses squids snails clams Annelids earthworms Arthropods insects spiders lobsters millipedes These are the invertebrate groups covered in this book