Where are the Glow Worms?

If you have only ever been to Bermuda during winter or spring, you might not be aware of the spectacular underwater shows that happen in the warmer months.

The Bermuda fireworm, simply referred to as “glow worms” locally, has precisely-timed bioluminescent mating habits that literally light up the ocean. This event has been well documented in history, and it is believed that Christopher Columbus and his crew glimpsed these creatures while sailing the Caribbean. In his diaries Columbus mentions “the flame of a small candle alternately raised and lowered” in the waters, which almost certainly refers to the green glow of the fireworms.

While the glowing lights in the ocean may be a spectacle for us, the entire process is vital the reproduction of glow worms. It is the female glow worms that produce bioluminescence, swimming in circles and releasing a glowing green slime, which contains their eggs. The males have eye adaptations that allow them to locate females and respond by emitting pulses of light and releasing their gametes into the water.

This process means that passing on genes is more opportunistic than competitive, and multiple males can fertilize the released eggs of one female. Researchers have found that up to 80% of released eggs were fertilized during the spawning event, confirming the glow worms’ reproductive efficiency.

But you won’t be able to witness the glow worms’ show just any night. Their mating schedule is quite precise: two nights after the full moon and 56 minutes after sunset during the summer and fall months. These spawning events last between 10 and 30 minutes.

Since the glow worms inhabit the sea bottom in shallow water and keep to an exact schedule, you can mark your calendar and watch the “glow show” from one of many spots across the island in the summer and fall months. Some popular locations include Flatt’s Inlet, Ferry Reach Bridge, Nonsuch Island, Mangrove Bay, and Ely’s Harbor, or you can even book a glow worm cruise through local boat charters, the Bermuda Aquarium, or Bermuda Underwater Exploration Institute.