Earthworm

An earthworm is a tube-shaped, segmented animal that is commonly found living in soil. Its digestive system runs straight through its body, it conducts respiration through the cuticle covering its skin, and it has a simple, closed blood circulatory system. Earthworms are hermaphrodites--each individual carries both male and female sex organs. As an invertebrate it lacks a skeleton, but an earthworm maintains its structure with fluid-filled chambers functioning like a hydro-skeleton.