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Unformatted text preview: is not contained entirely within vessels. closed circulatory system - a circulatory system in which the heart circulates blood through a network of blood vessels that form a closed loop. Three major groups of annelid worms are earthworms, marine worms, and leeches. Earthworms - most familiar worms. They eat materials in the soil. Their waste, called castings , make the soil richer for plants to grow. The digging also helps to loosen the soil to allow air and water to the roots of plants. Marine Worms covered with bristles comes in many colors - very pretty most live in the ocean They eat mollusks and other small animals. Leeches Three types: parasites that suck other animals blood scavengers that eat dead other animals predators that eat insects, slugs, and snails. Doctors sometimes use leeches to prevent swelling near a wound. 2...
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- Fall '10