Myzostomids: Myzostomida

Myzostomids are typically round in outline and flat. Their bodies measure 0.118 to 1.181 inches (3 to 30 millimeters) in length and are fringed with flexible, needle-thin projections called cirri (si-ri). The upper body surface is smooth, but the lower surface usually has five pairs of flaps used for moving around. Each flap is armed with small hooks to help them attach to their hosts, sea lilies. There are also four pairs of slitlike or suckerlike organs on the underside that probably act as sensory organs. In some species, these organs are greatly reduced in size or absent. Myzostomids feed by extending their throats forward out of the mouth inside out.