It’s getting dark; there are parents murmuring in the twilight and children running around, bored with the waiting. My feet dangle over the edge of the bridge’s wooden planks and the soft current rushes underneath, making small sloshing sounds. There are flashlights, snacks, blankets; everyone is ready for a show.
Then, suddenly, a light in the water. A green glow that’s only there for a second – maybe you imagined it; but then more, and then people begin to catch on, begin to shout excitedly. Flashlights are pointed at the water, but they’re not needed – the magic is in the light the animals themselves produce.
The male Bermuda Glow Worm (Odontosyllis enopla) is extremely punctual. It has to be in order to stand any chance of synchronizing its appearance and courting with females in the vicinity, and having the chance to mate. In Summer and early Fall, glow worms make their debut two days after the full moon at precisely 56 minutes after sunset. It’s not a random time; scientists have established that the organisms use lunar periodicity to time their emergence.
The physiology of the organism is completely dedicated to reproduction – males have eye adaptations which aid them in locating luminescent females, and females have glands in the epidermis which allow them to produce bioluminescence. During the displays, which last between 10 and 30 minutes, females release luminescent slime, which contains their eggs, and swim in circles, continuously emitting light. The males respond by emitting pulses of light and releasing their gametes in to the water.
The benthic (residing at the sea floor) species must undergo a metamorphosis to become a pelagic (residing open water) species for reproduction, and this metamorphosis is reversible. The larva produced by spawning begin as benthic juveniles.
Once thought to be the work of sea monsters, bioluminescence is actually an oxidation reaction which produces light. The light is deemed “cold light” since nearly 98% of the energy from the reaction is used to produce luminescence. Little is known of the glow worm outside of its reproductive habits, which draw attention from locals and tourists alike.