Corresponds with pages 62 through 68 in the textbook. Classifying Animals Corresponds with pages 62 through 68 in the textbook.

Classifying Animals Invertebrates are animals that do not have backbones. Simple invertebrates mostly live in aquatic environments. It includes sponges, cnidarians and worms.

Sponges Sponges have no true organization. Their bodies are asymmetrical. An asymmetrical body plan can not be divided into mirror images.

Cnidarians Cnidarians include sea anemones, corals and hydras. They have radial symmetry. This means their body plans are arranged around a central point.

An Example of Radial Symmetry

Worms All worms have Bilateral Symmetry. Their bodies can be divided along in half to produce two mirror images. There are three types of worms, flatworms, roundworms and Segmented worms.

Complex Invertebrates Complex Invertebrates are animals with complex body structures, such as specialized organs. Complex Invertebrates include Mollusks, echinoderms and arthropods.

Endoskeleton vs. Exoskeleton Echinoderms have an endoskeleton. Animals that have an endoskeleton have a skeleton on the inside of their bodies. Arthropods have an exoskeleton. Animals that have an exoskeleton have a skeleton on the outside of their bodie.

Vertebrates Vertebrates are animals that have a backbone. This includes fish, amphibians, reptiles, birds and mammals. All vertebrates have bilateral symmetry and endoskeletons.