The red tubeworm (Serpula vermicularis), also known as the plume worm, fan worm, or calcareous tubeworm, is a polychaete worm that is classified in the Annelida phylum. It can be found in many waters across the world including the Indian, Pacific, and Atlantic Oceans, but it has not been found along the North American coast. It prefers to reside at depths of up to 330 feet within the intertidal zone. This species attaches itself to hard substrate like boulders or the shells of bivalves, occasionally forming large colonies. If larvae attach themselves to other worms, they may form fragile reefs. These reefs are often destroyed, sometimes due to boring sponge activities.
The coral reefs created by the red tubeworm take years to form, but they are home to many species including sponges, bryozoans, hydroids, bivalves, ascidians, and specific species like the Pomatoceros triqueter worm, the Cancer pagurus crab, and the Asterias rubens starfish. One tunicate species, known as Pyura microcosmus, occurs along this reef and is not seen in any other habitat.
The red tubeworm can grow to reach 7.9 inches in height, but most individuals are smaller than this. Each worm resides in a slightly curved tube that is attached to a rock, with its head sticking out of the protective tube. This head holds about forty radioles that resemble feathers, which project from the second segment of the worm’s body and are red, white, or orange in color. This segment, called the peristomium, also holds the mouth and eyes of the worm. When the worm retracts into its tube completely, its operculum, or funnel-shaped lid, fills the opening. This covering, which is typically red in color, has 160 creases along the edges. The body, which remains hidden in the tube, is comprised of 190 abdominal segments and 7 thoracic segments. The shell of the red tubeworm is made of aragonite and calcite. Calcium is stored in two sacs located along the front side of the peristomium segment and is used with a secretion to create the shell.
The red tubeworm is a filter feeder and consumes detritus and phytoplankton by extending its radioles, which also serve as its gills. The oxygen the worm receives through these gills contains chlorocruorin, which is a strong agent that binds carbon monoxide together. The spawning season for this species occurs between June and September, after which time the larvae produced will float with phytoplankton for up to two months. Once the larvae have floated to the seabed, they grow quickly, reaching maturity in about ten months. Common predators of this species include starfish, sea urchins, Crenilabrus melops, and Ctenolabrus rupestris.
Image Caption: Serpula vermicularis (Croatia). Credit: Elapied/Wikipedia (CC BY-SA 2.0 FR)