phylum

also known as segmented worms, have a closed circulatory system.

• anthropods

• sponges

• annelids

• molluscs

are sessile animals that have specialized cells called amoebocytes and choanocytes

• annelids

• sponges

• echinoderms

• flatworms

have a pseudocoelom and are the simplest animals that have a complete digestive tract.

• molluscs

• cnidarians

• nematodes

• annelids

have jointed appendages and an exoskeleton that must be shed to permit growth

• anthropds

• molluscs

• flatworms

• sponges

exhibit two radial body forms, the polyp and the medusa, and use stinging cells to capture prey.

• molluscs

• nematodes

• cnidarians

• annelids

have a body plan with three main parts: a visceral mass, a mantle, and a foot

• annelids

• anothropods

• sponges

• molluscs

(meaning ''spiny skin'') have a water vascular system that functions in locomotion, feeding, and gas exchange.

• nematodes

• echinoderms

• annelids

• sponges

are the simplest bilaterian animals and lack a body cavity.

• anthropods

• nematodes

• annelids

• flatworms