Reef Bristleworm (Eurythoe sp.)
This large active bristleworm is often encountered on many of our shores, inhabiting coral rubble near living reefs and seagrasses. It is especially active at night, foraging busily among the rubble. During the day, the worms are often hidden under stones.
The Reef Bristleworm has a flat body which is broad and tapered at both ends. Along the body are two rows of parapodia, paired, lateral appendages extending from the body segments. Each parapodium is biramous, consisting of the upper division called the notopodium and a ventral division called the neuropodium. The setae or bristles on the underside are hooked and allow the worm to cling to the substrate.
The dorsal setae are composed of calcium carbonate and are brittle and hollow. Contact causes these setae to break off readily and the fragments will lodge in the skin, releasing a toxin known as complanine that will cause pain and inflammation. As a result, the Reef Bristleworm and its relatives are commonly known as Fireworms.
This worm is an omnivorous scavenger. It lacks jaws and teeth, but possesses eversible mouthparts that function like a suction pump. Larger pieces of food are ingested by the muscular pharynx, which can increase in size to handle different sizes of food. Smaller food particles are plucked from the water by the everted pharynx.
Similar-looking polychaete worms from all over the world have been referred to a single species, Eurythoe complanata. There is some debate over whether this is one widespread species or a complex of species that look similar.