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aortic arches

organs that help to control blood pressure in earthworms

bilateral symmetry

a type of symmetry in which there are two equal sides to an animal; only one possible plane will divide it into equal halves


one of many small blood vessels that have walls that are one cell thick; materials are exchanged between the blood and other body tissues in the capillaries

closed circulatory system

a type of circulation in which the blood remains in vessels

filter feeder

an organism that obtains food from water circulating through its body


a mass of nerve tissue; sometimes called a simple brain in many invertebrates


a type of stinging cell possessed by cnidarians; used for defense or for capturing food


tubelike structures that filter wastes from the blood in some organisms


a number of neurons arranged side by side and wrapped in a protective covering


a long, thin nerve cell that carries impluses between various parts of the body

radial symmetry

a type of symmetry in which several different planes could divide an animal into equal halves

sensory receptor

a structure capable of receiving a stimulus from the environment and sending an impluse along a neuron


a structure in animals and humans which provides mechanical support for muscle attachment and maintaining body shape


anything that causes a response in an organism


in animals a blood vessel that carries blood toward the heart; in plants, the vascular tissues in leaf blades


an animal without a backbone


phylum that the animals must have pores; example - sponges


phylum that have stinging cells; example - jellyfish


phylum that are flat worms; example - planarian


phylum that are roundworms; examples - roundworm (ascaris), hookworms, pinworms, trichina worms


phylum that are segmented worms; examples - earthworm, leeches, tubeworms, scale worms, clam worms, and lugworms


are living arganisms, eukarotic, multicellular, have organized tissues, and can move

gastrovascular cavity

digestive chamber of a jellyfish

hard corals

type of corals that help build coral reefs


type of symmetry of flatworms

flame cells and pores

structures that the planarian uses to romove wastes from its body


structures in the earthworm responsible for collecting wastes


the outer tissue layer in a jellyfish


protein component of some sponge skeletons


a type of skeleton similar to a water balloon


an animal in the same phylum as the jellyfish


number of layers of tissue found in a jellyfish

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