What happens when you drop a dead alligator in the darkest depths of the Gulf of Mexico?

It’s not a question that has plagued many scientists, but it has plagued at least one – Craig McClain, a marine biologist and executive director of the Louisiana Universities Marine Consortium in Cocodrie.

McClain wanted to see what unfolded if he introduced a rare calorie-rich reptile to the abyssal seafloor, a dark and nearly lifeless place with little food for the few critters dwelling there.

So last month, McClain and a team of LUMCON researchers plopped three adult alligator carcasses, each seven to eight feet long, into the Gulf, where they sunk to depths of more than a mile. They then deployed a live-feed video camera to cover the action.

It didn’t take long for one of the creepiest creatures of the deep to sniff out the gators. Giant isopods, each about a foot in length, swarmed in and began nibbling on what, to them, must have been a bountiful and exotic feast.

“We had assumed given the tough hide of the alligator it might take a while for deep-sea animals to access the soft tissue,” McClain said in email during an outing on a LUMCON research vessel. “But the giant isopods seemed to find soft spots in the hide on the abdomen and in the armpits.”

From the top, an isopod looks like a gargantuan version of the pill-bug, a land-dwelling cousin. Flip it over, and the pale, 14-legged crustacean resembles a ’facehugger’ from the movie Aliens.

Giant isopods crawl around the mostly barren seafloor hoping some edible morsel falls from near the surface. Decaying bits of fish and other organic matter become a white fluff as they sink beyond the reach of sunlight. This ‘marine snow’ is a prime but not especially rich food source for isopods. Occasionally, a whale carcass drops to the seafloor, but such food bonanzas are relatively rare in the deep sea. Isopods must go without eating for months, even years. An isopod at an aquarium in Japan managed to live for five years without food.

So it was no surprise that several isopods would quite literally dive into their alligator dinner.

“Once a hole was opened we observed giant isopods actually going inside the alligator,” McClain said.

McClain has long been fascinated with isopods. Last year, his lab live-tweeted an isopod dissection (a task that required bolt cutters). McClain once tried eating isopod, which he said tasted like ”old fried chicken and cheap faux seafood.”

But why serve an alligator, a resident of swamps and marshes, to sea critters that live more than a 100 miles offshore? McClain said alligator carcasses in the deep ocean are “not nearly as impossible as you might think.” Dead alligators have washed ashore on the Gulf and Atlantic coasts. Live ones have popped up on the sandy beaches near Grand Isle.

Alligators are sometimes pushed out to sea by river flooding and storms. After Hurricane Katrina, an alligator was seen swimming near an oil rig about 40 miles offshore.

Alligators vs. sharks: In Gulf Coast waterways the gators are winning, research finds A few years ago, a bird watcher was zooming her camera on a marsh bird when a photo-bombing alligator made the picture a lot more interesting.

Recent research shows that alligators make regular meals of sharks and stingrays. Alligators, which lack the salt glands of their crocodile relatives, frequently snap up sharks and rays that stray into rivers and bayous. They also ride the river runoff that spreads across the top of saltwater after a hard rain, giving them a chance to sample a variety of seafood.

From the 19th century, when alligators were more abundant, there are several accounts of alligator vs. shark battles off the Florida and Gulf coasts. An 1877 magazine story recounts how a school of fish trapped in a south Florida inlet attracted rival gangs of gators and sharks. Witnesses said the beasts could be seen fighting in the crests of waves.

Large marine reptiles may have been a big part of the deep-sea food chain during the time of dinosaurs, McClain said. A variety of dolphin- and fish-shaped ichthyosaurs and immense mosasaurs thrived in the deep ocean. Fossil records indicate some deep-sea mollusks and limpets may have depended on sunken reptiles.

“When these prehistoric sea monsters died and fell to the seafloor, they may have served as the host for a whole community of deep-sea animals,” McClain said. “Do modern alligator and crocodiles serve as the last remaining refuges for these faunas?”

McClain acquired the alligators from the state Department of Wildlife and Fisheries, which culls wild alligators to control their populations in ecologically-sensitive areas. He plans to return to the three alligators in a year or two to check for bone-eating worms and snails that are often drawn to whale carcasses.

The research is another flash of light into an area of the planet that has been “shrouded in mystery,” McClain said. Much of the deep ocean is unexplored. We have a better understanding of Mars’ topography than Earth’s seafloor, of which only 20 percent has been mapped, according to the National Oceanic and Atmospheric Administration. Recent advances in technology have sparked a boom in ocean research. Underwater robotics, video and sound recording gear and remote operated vehicles (ROVs), like the one McClain used to study the sunken alligators, are now widely accessible to scientists. Deep sea discoveries have become almost commonplace, McClain said.

“Every sample of life we bring from the abyss contains a cornucopia of species never seen by humans before and unknown to science,” he said.