Pictures: Glowing Deep-Sea Creatures Found in Caribbean

Bright Eyes

Photograph by Edith Widder, ORCA

Giant isopods (pictured)—such as this specimen caught during the 2009 expedition—can grow to 16 inches (41 centimeters) and have compound eyes that are extremely sensitive to low light levels. Light bounces off a reflective layer at the back of the eyes called the tapetum, making the eyes appear to glow.

To bring up animals like this from the deep sea and study their vision in the laboratory, scientists have to keep them in the dark. "Surface light levels will blind them," said Frank.

That's why the team carefully collected animals one by one using a mechanical arm on the submersible vessel before placing them inside light-tight, insulated boxes.

(Watch a video of a giant isopod kept at the Smithsonian Institution.)

Published October 10, 2012

Eyeing Dinner

Image courtesy NOAA-OER

Brittle stars surround a squat lobster on the seafloor.

From inside the submersible, the team watched as squat lobsters sat on top of green-glowing anemones and "every so often used one of their long claws to pick something off and stick it in their mouths," Frank said.

"It seemed to us that they weren't actually feeding on the anemone—they were feeding on something that was stuck on the anemone," she said.

Team member Sönke Johnson noticed dim flashes of blue light made by passing plankton, which were bumping into the anemone. This gave the team the idea that the lobster's ability to see blue and UV light could allow them to better spot the tasty blue plankton against the green anemone.

(See pictures: "New Squat Lobsters Found off Australia.")

Published October 10, 2012

Glowing Goo

Image courtesy NOAA-OER

A venus flytrap anemone releases a cloud of glowing goo to confuse predators in a laboratory image. The species is one of two deep-sea anemone species known to create their own light, the team says.

The anemone's bioluminescent mucus sticks to an advancing predator, making it shine brightly and possibly attract the attention of a second predator. "It's like a burglar alarm," Frank said.

(See "Thirteen Stunning Photos From Ten-Year Sea Census.")

Published October 10, 2012

Shimmering Brittle Star

Photograph by Edith Widder, ORCA

A shimmering brittle star (pictured) is one of the deep-sea species recently found to produce light.

While aboard the submersible, the research team approached a variety of animals on the seabed and gently prodded them to see which ones glow.

"The nice thing about the sub is you can sit it on the bottom and turn almost everything off, so it's very quiet," Frank said. "You're not disturbing things other than the things you want to disturb."

(See "Undersea Mountain Photos: Brittlestar Swarm, More Found.")

Published October 10, 2012

Glowing Bristles

Image courtesy NOAA-OER

Bristles glow around the mouth of a deep-sea crab.

Since so few bioluminescence studies focus on the deep seafloor, it's unclear whether the trait is generally rare at this level of the ocean or whether the situation is unique to the Bahamas.

"We really need to get out there and look at more regions and see if what we discovered on this trip is valid," Frank said.

However, due to budget cuts, the Harbor Branch Oceanographic Institute at Florida Atlantic University has sold the ship that launches the sub used during the expedition.

"Its really tragic that the Johnson Sea-Link is no longer operational," said Frank, whose study was published in September in the Journal of Experiment Biology.

(Also see "Glowing Animals: Pictures of Beasts Shining for Science.")

Published October 10, 2012

Ocean Squatter

Image by Edith Widder, ORCA

A deep-sea squat lobster sits atop a zooanthid species that's awaiting formal identification. These anemones are the dominant species at a site called Memory Rock, about 1,970 feet (600 meters) deep off Grand Bahama Island.

"It looks like a coral with all these branches on it and has this lovely greenish bioluminescence," Frank said. "You tap one portion of it and you see the light ripple up the colony."

(Pictures: "New 'Green Bomber' Sea Worms Fire Glowing Blobs.")

Published October 10, 2012

What Big Eyes You Have

Image courtesy NOAA-OER

An inch-long (2.5-centimeter-long) squat lobster known as Gastroptychus spinifer has relatively large eyes, which help it detect bioluminscent light in the deep sea, the team discovered.

A major challenge in studying deep-sea inhabitants is making sure they don't overheat when bringing them to the surface—especially when working in the tropics.

"Most people think that it's pressure that kills deep-sea animals when you bring them to the surface," Frank said.

But bringing creatures from temperatures of around 39 to 45 degrees Fahrenheit (4 to 7 degrees Celsius) to about 81 degrees Fahrenheit (28 degrees Celsius), can "fry them," she said.

(See a picture of an anglerfish with two glowing lures.)

Published October 10, 2012

Black Devil

Photograph by Edith Widder, ORCA

A female anglerfish known as a humpback black devil dangles a bioluminescent lure to tempt prey into her snaggletoothed maw.

For species like the black devil, which live in the water column rather than on the seafloor, the ability to make light is commonplace—often as a way of disappearing where there's no place to hide.

For instance, open-water species can hide their silhouettes by producing bioluminescence on their undersides to match light coming from the surface.

But on the seafloor, there are more places to hide—which may explain why bioluminescence is so rare at the bottom of the ocean, Frank noted.

Published October 10, 2012

Next: Glowing Sea Beasts—Photos Shed Light on Bioluminescence

Image courtesy Edith Widder, ORCA

Published October 10, 2012