Animal Kingdom Overview Multicellular Heterotrophic Eukaryotic Reproduce: Asexually and Sexually Important phyla cnidarians mollusks annelids arthropods echinoderms chordates The cnidarian phylum includes animals that live in water and have a central opening surrounded by tentacles. This opening is used for taking in food and eliminating wastes. Jellyfish, sea anemones, and corals are examples of cnidarians. Mostly marine organisms, there are a few that live in freshwater. On the tentacles are nematocysts. These are the structures responsible for causing the "sting". The mollusk phylum includes animals that live on land and in both fresh and marine water. They have a muscular foot that is used to hunt for food and move. They have a radula which is a rough tongue used to grab and eat food. Snails, clams, and octopuses are examples of mollusks. These organisms have soft bodies. The annelid phylum includes animals that live on land and in water (both fresh and marine). They are called segmented worms because they have bodies that are made up of many connected sections called segments. Earthworms, leeches and some sea-floor worms are examples of annelids. The arthropod phylum includes animals that live on land, in water, and in the air. They have an outer covering called an exoskeleton, a segmented body, and jointed appendages or legs. Arthropods go through periods of molting to shed their exoskeleton. Some arthropods also have wings. Crabs, spiders, and insects are examples of arthropods. The echinoderm phylum includes animals that live in water. Their bodies have radial symmetry and a central opening for taking in food. Radial symmetry means that the organism has no right or left sides. Their bodies are laid out in a circle with identical parts arranged around a central mouth. Sand dollars, sea urchins, and sea stars are examples of echinoderms. The chordate phylum includes animals that live on land, in the water and in the air. Most chordates are vertebrates. This means they have a backbone. At some point in their lives all chordates have a flexible rod called a notochord that supports their backs, a nerve cord that runs down their backs, and slits in their throats. In some chordates, such as humans, a backbone replaces the notochord and the slits in the throat close before birth. Humans, birds, snakes and fish are examples of chordates. Warm blooded organisms are mammals, cold blooded are fish, reptiles and amphibians Mammals have hair, give birth to live young and produce mild for their young.