''Odontosyllis enopla'', commonly known as the Bermuda fireworm, is a

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ma ...

that inhabits shallow areas of the western Atlantic Ocean. The organism is

bioluminescent Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some fungi, microorganisms inc ...

when it rises to the surface of the sea during its mating period. It is possible that this fireworm is the explanation of a candle-like light seen by

Christopher Columbus Christopher Columbus (; between 25 August and 31 October 1451 – 20 May 1506) was an Italians, Italian explorer and navigator from the Republic of Genoa who completed Voyages of Christopher Columbus, four Spanish-based voyages across the At ...

during his first voyage on 11 October 1492 before he made landfall in his explorations.

Description

As a polychaete worm, ''Odontosyllis enopla'' has a body consisting of multiple segments each with a pair of

parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed late ...

. The head has two pairs of eyes at the sides with several advanced features including a lens, photoreceptor cells, a retina and pigment granules. Associated with these are linear arrays of tubes which may function in a similar way to

fibre optic An optical fiber, or optical fibre, is a flexible glass or plastic fiber that can transmit light from one end to the other. Such fibers find wide usage in fiber-optic communications, where they permit transmission over longer distances and at ...

bundles. Each pair of eyes is oriented in a different plane. Female worms grow to or longer while males typically grow to . This worm normally lives in a mucous tube on the shallow seabed.

Distribution

''Odontosyllis enopla'' is native to Bermuda, the Bahamas, the southeastern Atlantic coast of the US (Georgia, Florida and Texas), the West Indies, the Caribbean Sea and the Gulf of Mexico. '' Odontosyllis phosphorea'' is a similar species found in the eastern Pacific Ocean.

Behaviour

This small worm is normally inconspicuous, dwelling inside its tube concealed among corals and algae on the seabed, however in the breeding season it changes its behaviour. Reproduction takes place in the summer, two to five days after the full moon; in the early night, female worms leave their tubes and rise to the surface. The timing of their ascent is very precise, taking place exactly 55 minutes after sunset. On the surface, they swim in tight circles, secreting

mucus Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...

along the length of their bodies which emits flashes of bluish-green light. The female worms are soon joined by males, also emitting flashes of light, and they gyrate together, releasing

gamete A gamete ( ) is a Ploidy#Haploid and monoploid, haploid cell that fuses with another haploid cell during fertilization in organisms that Sexual reproduction, reproduce sexually. Gametes are an organism's reproductive cells, also referred to as s ...

s into the water. After ten to fifteen minutes the

spawning Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...

period is over and light emission ceases, the worms swim to the bottom, discard their swimming

seta In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae, ...

e (bristles) and build themselves new tubes. The bioluminescence indicates to the male the spot at which a female is releasing its eggs, and the complex eye mechanism enables the male to accurately locate the position. Tests of water samples taken from the surrounding area show that 45 to 80% of the eggs are successfully fertilised by this reproductive strategy.

References

{{Taxonbar, from=Q2938428 Syllidae Bioluminescent annelids Animals described in 1900