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By Phil Colarusso
Saturday night is usually the big social night on the weekly calendars of most humans. Who knew that sea worms kept the same schedule?
Fellow EPA diver Dan Arsenault and I braved the north Atlantic just after sunset on a recent Saturday evening. Night diving requires a little more planning than the same dive executed during the day. Each diver carries a waterproof dive light, generally with a fresh set of batteries for each dive. In addition, we attach a glow stick to the dive flag and place a second one on the beach where we leave our shoes, car keys and towels. The glow stick on the dive flag helps divers who get separated to find each other and the one on the beach helps us find our car keys.
Some animals are easier to find at night, such as squid, which are more abundant at night and are attracted to dive lights. Lobsters also tend to be much more active at night, emerging from their burrows to roam their respective neighborhoods looking for food. Fish, such as Atlantic cod, generally found in deeper water during the day, venture into shallower waters at night.
At night, there is also always the sense that something unusual is just around the corner. This recent night dive was a perfect example. Dan had found a beautiful fish called a longhorn sculpin, which I was filming. Out of the corner of my eye, I noticed what appeared to be a rocket rising with white smoke trailing behind it. After a closer look, I realized the “rocket” was really a 12 inch long sea worm and the smoke was clouds of sperm. We had caught the worm in the act of spawning, which only happens a few nights a year in and around the full moon.
Unfortunately for the sea worm, his frantic flight also drew the attention of a large fish known as a cunner. As the sea worm released its gametes in a writhing dance, the cunner tried to figure out how to take a bite. Finally, it inhaled the entire worm in two gulps and swam off with the white cloud of worm gametes streaming out of its gills. This type of interaction generally occurs only at night and Dan and I were incredibly fortunate to witness it. You can see a 30 second clip here:
About the author: Phil Colarusso is a marine biologist in the Coastal and Ocean Protection Section of EPA New England, and is an avid diver. He’s living the dream with wife JoAnn, two kids, dog and white picket fence.
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