Phoronids: Phoronida

Phoronids (for-OH-nihds) are long, thin, wormlike animals that live inside slender tubes that they make with their own bodies. When relaxed, adults normally measure up to 18 inches (450 millimeters), but some phoronids can extend their bodies nearly five times that length. Their body thickness measures 0.006 to 0.2 inches (0.15 to 5 millimeters). There is no distinct head. The slitlike mouth is covered by a flap of skin and is found between the horseshoe-shaped, tentacle-bearing ridges that make up the lophophore (LO-fo-for). The tentacles of the lophophore help phoronids to breathe, eat, and protect themselves. The ends of the horseshoe-shaped ridges are coiled like springs. The slender body trunk is swollen, or bulb-shaped, at the end. This region of the body contains most of the internal organs.

Inside they have a body cavity and a u-shaped digestive system. The nervous system includes a nerve center between the mouth and the anus. The anus is located at the end of the digestive system and is where solid waste leaves the body. At the base of the lophophore is a ringlike nerve structure. Phoronids have blood that circulates inside a system of tubes, or vessels. They have a pair of kidneylike organs that not only remove wastes from the blood, they also work as part of the reproductive system.