Life Cycle

The worm known as the “fireworm”, the Odontosyllis phosphorea reproduces sexually and has separate sexes (Tsuji and Hill, 1983). These worms have a very specific external mating ritual in tune with each month’s quarter moons (Pickett, 2012). The ritual happens one or two days before a quarter moon, begins around 30 to 40 minutes after sunset, and lasts around 20 to 30 minutes (Pickett, 2012). O. phosphorea females start the ritual by rising from their underwater benthic level habitat and swim towards the surface (Deheyn and Latz, 2009). The female worms produce bioluminescent blue-green mucus while slowly swimming in circles releasing gametes about two centimeters below the surface of the water (Jones and Wood, 2006). The glow allows the males visual indicators of the position of the females’ gametes.  Males also emit short pulses of light while swim up towards the surface of the water to release their gametes (Jones and Wood, 2006). Watch the awesome video below of the sister species Odontosyllis enola during their identical mating ritual (Figure 1.).  More than one male will take place in germinating the females’ eggs since all gametes, male and female, are released into the surrounding water (Jones and Wood, 2006). In a study of Odontosyllis enopla, a sister species of Odontosyllis phosphorea, Galloway and Welch took random samples of the water surrounding the fireworms after the spawning event and found that 45-80 percent of the eggs were fertilized, which shows the efficiency of the worms reproductive strategy (Jones and Wood, 2006).  Explained more in the interactions page the O. phosphorea females also use their blue-green glow as a defense mechanism (Pickett, 2012).                                      

Figure 1. Video of Burmuda glow worms, Odontosyllis enola. Promission courtesy of greydek. This video was taken by greydek September 14th 2011. Check out his other videos of marine organisms at http://www.youtube.com/user/graydek?feature=watch.  

Dr. Dimitri Deheyn, a well-known Marine Biologist at the University of California-San Diego studied the time period of the ritual and glow of the O. phosphorea. Regarding the question of if the bioluminescence is long enough to be seen by the male O. phosphorea, Dr. Deheyn said,

 “Well, it’s long enough. [The swarming] happens at twilight, so the daytime predators have gone to bed and the nighttime predators haven’t become active yet, but they still have to balance making enough light for their sexual partner to find them without making too much light, which could attract predators. To us it doesn’t seem like much light, but for them, it is enough”(Pickett, 2012).

Figure 2. Bioluminescence of O. phosphorea. Image courtesy of Dimitri Deheyn, Scripps Institution of Oceanography at UC San Diego. 

This quote does a great job of showing the balance of sexual selection and predation. Learn more about what prays on Odontosyllis phosphorea on our interactions page.

Know that the ultimate question of why O. phosphorea secretes their bioluminescent mucus, lets ask the proximate question of how the bioluminescent occurs. A study done by Dimitri D. Deheyn and Michael I. Latz was done to test if the bioluminescence was due to a photoprotein or if it is do to a luciferin-luciferase reaction-taking place within the organism similar to other bioluminescent organisms (Deheyn and Latz, 2009). Luciferin reactions and photoprotein are very similar bioluminescent reactions (Wilson, 2008). Luciferase acts as a catalyst for luciferin to combine with oxygen, and it is the luciferase catalyst that actually emits photons of light (Wilson, 2008). Photoproteins are proteins that generate light when oxidized without the aid of any enzyme (Wilson, 2008). The conclusion made from the study was that O. phosphorea use photoproteins instead of a luciferase reaction, but could not pinpoint a specific photoprotein (Deheyn and Latz, 2009). Although the study was not successful at finding a specific photoprotein in charge of O. phosphorea’s bioluminescent, the results from their study will help further studies on the purification and identification of compounds involved (Deheyn and Latz, 2009). Check out Noctiluca scintillans and Photinus pyralis different orgainsims that use luciferin-luciferase reaction instead of photoproteins like Odontosyllis phosphorea.

Figure 3. O. phosphorea. Picture taken by Greg Rouse.

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