Invertebrate Summary

Phylum Porifera Sponges are classified as animals because they are multicellular, heterotrophic, have no cell walls, and contain a few specialized cells. Sponges are classified as animals because they are multicellular, heterotrophic, have no cell walls, and contain a few specialized cells. Asymmetrical Asymmetrical Ex: sponges Ex: sponges

Cnidarians Soft-bodied, carnivorous animals that have stinging tentacles arranged in circles around their mouth. They are the simplest animals to have body symmetry and specialized cells Soft-bodied, carnivorous animals that have stinging tentacles arranged in circles around their mouth. They are the simplest animals to have body symmetry and specialized cells Radial Symmetry Radial Symmetry Ex: jell fish and hydra Ex: jell fish and hydra

Flatworms Soft, flattened worms that have tissues and internal organ systems. They are the simplest animals to have three embryonic germ layers, bilateral symmetry and cephalization Soft, flattened worms that have tissues and internal organ systems. They are the simplest animals to have three embryonic germ layers, bilateral symmetry and cephalization Acoelomates Acoelomates Ex: tapeworms, flukes,turbellarians Ex: tapeworms, flukes,turbellarians

Roundworms Unsegmented worms that have pseudocoeloms and digestive systems with two openings-a mouth and an anus Unsegmented worms that have pseudocoeloms and digestive systems with two openings-a mouth and an anus Bilateral Bilateral Ex: hookworm, heart worms, Elephantiasis Ex: hookworm, heart worms, Elephantiasis

Annelid Worms with segmented bodies. They have a true coelom that is lined with tissue derived from mesoderm. Worms with segmented bodies. They have a true coelom that is lined with tissue derived from mesoderm. Closed circulatory system Closed circulatory system Ex: earthworms, leeches, sandworms Ex: earthworms, leeches, sandworms

Mollusks Soft bodied animals that usually have an internal or external shell Soft bodied animals that usually have an internal or external shell Open circulatory system Open circulatory system Bilateral symmetry Bilateral symmetry Ex: snails, slugs, clams, squid, and octopi Ex: snails, slugs, clams, squid, and octopi

Arthropod Segmented body, a tough exoskeleton (chitin), jointed appendages. Segmented body, a tough exoskeleton (chitin), jointed appendages. Open circulatory system with well defined heart Open circulatory system with well defined heart Cephalization (sense organs in the “head” area) Cephalization (sense organs in the “head” area) Ex: crustaceans, arachnids, insects Ex: crustaceans, arachnids, insects

Echinoderm Echinoderms are characterized by spiny skin, an internal skeleton, a water vascular system, and suction cup like structures called tube feet. Most adult echinoderms exhibit five –part radial symmetry Echinoderms are characterized by spiny skin, an internal skeleton, a water vascular system, and suction cup like structures called tube feet. Most adult echinoderms exhibit five –part radial symmetry Ex: sea star, sea cucumber, sand dollars, brittle stars Ex: sea star, sea cucumber, sand dollars, brittle stars