Loricifera

Loricifera A phylum, first described in 1983 by R. M. Kristensen, of animals only 0.25 mm long that live in marine gravel. The body bears a cuticle of four plates (one dorsal, one ventral, two lateral) and has recurved spines on the anterior end. The anus is terminal. Sexes are separate; larvae resemble small adults. The phylum appears to be related to the Priapulida (priapus worms) and Kinorhyncha.

Loricifera , phylum of microscopic animals discovered in 1974. They have spiny heads and unsegmented bodies encased in a vase-shaped anterior that can retract into the posterior trunk. Although research shows that the sexes are separate and they have a large brain, little else is known about them. Because they adhere tightly to the marine gravel or sand in which they live, they are difficult to extract. They hatch as a larval stage, undergo several molts, and reach adult stage. As with the Gnathustomulida , this may account for their late discovery. Locierans appear to be most closely related to the kinorhynchs ( Kinorhyncha ) and priapulids.