INVERTEBRATES: ANIMALS WITHOUT BACKBONES Most Animals are Invertebrates! Animals are classified into groups so that scientists around the world can study them easier. Scientists classify animals into two major groups, vertebrates and invertebrates. Invertebrates are animals that do not have a backbone. Many invertebrates do not have hard body parts either, though some do. Scientists classify invertebrates into broad groups called phyla, such as cnidarians, echinoderms, mollusks, and arthropods. Invertebrates are classified into phyla based on their symmetry and body plan. There are many different invertebrates living on Earth. In fact, MOST of the organisms living on Earth are invertebrates. Lesson Checkpoint: What do invertebrates NOT have? Sponges Sponges are invertebrates that are simple organisms. Sponges live attached to a fixed location in the water. Most sponges live in salt water. Sponges have holes, called pores, which allow water to flow through them. They get their food from the water that flows through them. Lesson Checkpoint: Where do most sponges live? © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.
Cnidarians Cnidarians include hydra, jelly fish, and sea anemones. Cnidarians have several things they have in common with each other. One characteristic they have in common is that they all have stinging cells. Cnidarians include hydra, which are organisms that live in freshwater. Cnidarians also include jellyfish. Jellyfish have soft bodies and long stinging tentacles that are poisonous. Sea anemones look like flowers in the sea and live attached to objects in the sea. Lesson Checkpoint: What is one characteristic that cnidarians have in common? Worms Worms are also invertebrates. Worms have segmented bodies, which means they have bodies that are divided into sections. An example of a flatworm is a tapeworm, which is a type of worm that lives off another living thing. Leeches are also classified as invertebrates and have segmented bodies. Lesson Checkpoint: How does a tapeworm live? © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.
Mollusks Snail and clams are types of mollusks. Mollusks have soft bodies and most mollusks have shells. Mollusks, like a snail, move by using a structure called a foot. This foot produces slime that helps the snail move easier along the ground. Lesson Checkpoint: What is an example of a mollusk? Echinoderms Echinoderms are invertebrates that show radial symmetry and include starfish and sea urchins. Echinoderms live on the ocean floor and can only be found in salt water. Lesson Checkpoint: Where does an echinoderm live? © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.
Arthropods Arthropods are the largest animal phylum. Two characteristics of arthropods are that they have segmented bodies and jointed legs. Spiders Spiders are NOT insects. Spiders only have two main body parts and eight legs. Insects have THREE main body parts and SIX legs. Arachnids are spiders. They have an exoskeleton and jointed legs. Centipedes and Millipedes Other invertebrates include centipedes and millipedes. Centipedes and millipedes both have hard exoskeletons, which is their hard outer body. Crustaceans Speaking of having a hard outside, crustaceans are invertebrates and include crabs and lobsters, which have hard external shells. Lesson Checkpoint: Are spiders insects? Why or why not? © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.
Coral Reefs Coral reefs are a mass or ridge of living coral that need sunshine and warm waters to survive. Coral reefs live in warm, shallow sea waters. Coral reefs provide a protective place to live for a large variety of marine life. Lesson Checkpoint: What do coral reefs provide? © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.