San José, Costa Rica, since 1956

Glowing, Exploding Worms Light Up Night Dive

If you’ve ever gone looking for stars or celestial events, you know how difficult it can be to reach the truly dark places – places where there is no night light pollution, where you can really see the stars shine. Even a little light can ruin the view of faint stars.

That’s why Tom and I were deep in a canyon. But we weren’t looking for stars; we were looking for the floating luminescent spawn of coral and other bioluminescent marine life.

Countless forms of marine life produce their own light, and their glow may be any color.Tiny, drifting plankton that fill the water light up with any movement: a boat’s wake, a hand’s wave, a dolphin’s trail, a fin’s kick and a breaking wave all make light – light you can see only if surrounded by dark. The steep and narrow canyon was made of coral, and it was very dark with our lights turned off.

We floated over a tiny patch of sand 20 meters below the dark surface of a smooth Caribbean Sea, a few kilometers offshore of Manzanillo, on the southern Caribbean coast. The coral reef looked like city lights on a moonless night, and the water swirled with sparks and glowing clouds made from small currents and eddies moving against the canyon’s walls. Swimming fish left bright light trails as they darted about like moving sparklers.

Throughout the whole scene, like a constant grand finale at a fireworks show, drifted tiny multicolored spheres of coral spawn. A coral reef is made of millions of wee animals. That night, they were each spawning their progeny into the currents of the sea, like fields of dandelion flowers releasing floating seeds into the breeze.

Some of the coral eggs glowed blue, others yellow, orange and green and everything in between. Everywhere, faint and bright lights whirled and pulsed and spun as the luminescent coral reef of the future blew about the seascape. If you can imagine a sky full of snow with a glow, combined with a forest in flower blown by the wind, together with a wet field full of fireflies beneath the stars on a moonless night far from the city, you have a slight idea of what the bottom of the sea looked like that night.

Then, something amazing happened. As if on cue, small, corkscrew-like, wormlike creatures began launching themselves out of the walls of the canyon. Each one was about the size of a woman’s finger and curly like some people’s hair, or a wood chip, or a pig’s tail. Each one glowed a solid hue; many were shades of purple, but they came in multiple colors, some darker and some lighter.

There were hundreds of them all around us. The strange critters slowly spun like spinning corkscrews, arcing up and away from the reef. They twirled gradually up, creeping toward the center of the dark canyon. Then, another incredible thing happened.

 As each one reached the top of a trajectory describing an arc, it exploded into small clouds of glitter. The misty glitters of light twinkled as they slowly dropped like pixie dust, and, little by little, faded out. Many worms began to explode against each other, popping into drifting, falling clouds of fading light. They exploded on my hands and on the glass of my dive mask. The currents mixed all the lights together and the black canyon shone with luminescent life. I transcended to another level of consciousness and forgot about time.

Then a thought struck me like a jolting electric shock. Where was Tom? Here I was, guiding a trip, and I forgot about my client, not to mention time.When you’re scuba diving, it’s very important to check your time to make sure you do not exceed important time depth limits. If you forget, it can be something like forgetting you are driving a car –in other words, not good.

I exposed my gauges and saw I still had plenty of air and time.More than 10 minuets had passed since I last realized that I was scuba diving 20 meters deep on an offshore outer reef with my friend Tom, who was paying me to watch out for him and show him marine life.Where was Tom?

Then I saw Tom’s black shadow like a shape defined by the faint outline of a shifting aura of sparks around his body, caused by currents and his small movements lighting up the bioluminescent plankton. Tom was right there. He had not moved and he did not look like he was thinking much about me. He floated, apparently transfixed by the dazzling light spectacle.

I touched Tom’s arm and he jumped as if I were an electric great white shark.We peered at each other’s black shapes and shifting auras, and then Tom looked at his gauges.

Then he looked back at me and gave me the sign for “totally stoked.” I repeated it with both hands and we went back to watching the night life going off all around us.

After a while, the sound of our scuba tanks banging together made us check gauges again and we realized it was time to go.We both hesitated a long time before we had to turn on our dive lights to make it out of the canyon without touching or breaking any coral or other reef life. As soon as I fingered the switch, the entire fabulous show of radiance disappeared in a flash.

Coral spawning takes place each April and October on the reefs of Costa Rica’s southern Caribbean coast. Bioluminescence shines in the waters off both Pacific and Caribbean beaches. The glow seems strongest after a sunny day, and is best seen on dark nights.


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