Staff from the New England Aquarium recently traveled to Belize as part of a long-term research program run by Aquarium scientist Randi Rotjan, PhD, to monitor coral health near Carrie Bow Cay. Today's post from aquarist Peter Gawne, who was able to photograph some spectacular sights on a night dive, is part of that series.

Channel clinging crabs (Mithrax spinosissimus) leave the shelter of the reef to forage at night. This particular specimen’s legs spanned over 2 feet.

We had a little extra motivation on our last night at Carrie Bow, so we decided to head out and see the reef after sunset. While it can be difficult to build the enthusiasm for a night dive after a long day of diving, I have yet to feel remorse for having done one.

Caribbean reef squid (Sepioteuthis sepioidea) is attracted to the lights, and poses briefly for the camera.

During the short boat ride out to our chosen spot, we noticed an unusual amount of bioluminescence in our wake. Small flashes of blue-green visible light spread out behind the boat, likely bioluminescent algae which emit flashes of light when their environment is disturbed. Bioluminescence is light produced by a chemical reaction within a living organism. While we most often observe this phenomenon on hot nights in the summertime in the form of fireflies, most bioluminescent organisms are found in the ocean in the form of fish, jellies and bacteria.

This queen parrotfish’s (Scarus vetula) mucus cocoon may shield it from parasites while it sleeps.

We got a chance to see some animals that we rarely see during the day. After more than 200 dives at Carrie Bow Caye, I saw my first Belizean blackfin snapper (Lutjanus buccanella), bonnetmouth (Emmelichthyops atlanticus), and southern sennet (Sphyraena picudilla) on this night dive. Parrotfish, while seen regularly during the day, rest in mucus cocoons at night. Parrotfish secrete a mucus bubble which may function as a “mosquito net”, protecting them from gnathiid isopods, and other biting parasites, while they sleep.

While typically reclusive during the day, octopuses are often seen out of their dens during night dives.

It was great to get out for one last dive here at Carrie Bow. Special thanks to the Smithsonian’s Zach Foltz and M. Scott Jones, and the University of North Carolina’s Clare Fieseler for making the trip both successful and memorable. It has been a great trip!