Müller's Larva

the free-swimming marine larva of some polycladid Turbellaria; it was discovered by J. Müller in 1850. The body is egg-shaped, with eight to ten lobes that bear a ciliated band; sometimes the upper and lower poles of the body have a bundle of sensory flagella. On the ventral side of the body is the mouth opening, which leads to the pharynx. As the Müller’s larva develops, the rear of the body elongates, the entire body flattens, the lobes diminish, and, descending to the bottom, the larva becomes a worm.