Bearded fireworms are usually between 5–10 centimetres (1.9–3.9 in) in length, but can reach up to 35 centimetres (13.8 in). They are endowed with a group of poisonous white bristles on each side, which are flared out when the worm is disturbed.
The bearded fireworm is usually found on reefs, under stones in rocky areas of the sea, and on some mud bottoms. It is encountered throughout the tropical western Atlantic and at Ascension Island in mid-Atlantic. It can be found near ocean reefs and at depths of up to 150m. These worms are also common in the mediterranean sea, in the coastal waters surrounding Cyprus and the Maltese archipelago.
Disposition and defences
The bearded fireworm is a slow creature, and is not considered a threat to humans unless touched by a careless swimmer. The bristles, when flared, can penetrate human skin, injecting a powerful neurotoxin and producing intense irritation and a painful burning sensation around the area of contact. The sting can also lead to nausea and dizziness. This sensation lasts up to a few hours, but a painful tingling can continue to be felt around the area of contact. In a case of accidental contact, application and removal of adhesive tape will help remove the spines; applying alcohol to the area will also help alleviate the pain.