Bioluminescent Organisms

Darrin Schultz writes: I work in Steve Haddock’s lab where I study bioluminescent organisms, animals that make their own light, much like fireflies. On our leg of the Gulf of California expedition, we have seen and documented many luminous creatures, including jellyfish, shrimp, fish, comb jellies, worms, tiny crustaceans, and even “glowing dolphins” surrounded by luminous plankton in the water.

The ROV is configurable to suit each scientist’s research needs, and in our case, we attach a custom array of blue LED lights to help find animals that fluoresce (like highlighter ink under a black light). When we come upon a potential candidate, we shut off all of the vehicle’s white lights and shine blue light only. If the animal is capable of producing fluorescence it will glow green, yellow, or sometimes even red, when the blue light excites special proteins. We found several such fish on this cruise, such as a small one with brilliant green fluorescent eyes, and a dragonfish with fluorescent spots on its belly.

One of the main groups of animals we have been filming is the ctenophores (pronounced TEEN-oh-fores), or comb jellies. They’re actually not closely related to jellyfish, and they usually look like translucent underwater eggs with iridescent stripes that propel them through the water. Some ctenophores resemble Darth Vader’s TIE Fighter made of gelatin, swimming through the water with wing-like lobes.

By 9:00 p.m. we emerge from the dark room to take a short break on the deck of the ship. The water below is filled with tiny bioluminescent creatures smaller than grains of rice, which flash when the water around them is disturbed. Looking over the stern of the boat, I see a streak of water glow intensely blue, stimulated by the churning of the propellers.

At the bow, there are strange glowing shapes weaving to and fro. Confused at first, I hear high-pitched calls and quickly realize that it is a small pod of dolphins! The bioluminescent zooplankton in the water light up when they come in contact with the dolphins, and illuminate a perfect outline of dolphin snouts, fins, bodies, and tails. As the dolphins swim along, the bioluminescent lights stream behind them like shooting stars, leading us to our next dive site.

Back in the lab later that evening, we film the scintillating blue glow of the marine worm, Flota, and the yellow bioluminescent explosion from another worm, Tomopteris. Identifying bioluminescent animals allows us to use molecular (DNA-related) techniques to determine the genes involved in bioluminescence. In addition to studying the relationships of marine animals using their luminescent proteins, Steve is interested in identifying and cloning the genes involved, to understand how bioluminescence came to be so widespread in the sea.

It’s midnight now and things are starting to wind down. All of the animals have been sketched, photographed, labeled, and put away to study at a later date. The sun never sets for scientists who study bioluminescence.

-Darrin Schultz