Deep-Sea 'Graveyard' Reveals Demise of Ocean Giants

A deep-sea graveyard discovered by chance off the coast of Angola may help scientists reveal the fate of dead ocean giants, according to findings published in the journal PLOS ONE.

The carcasses of four large marine creatures - a whale shark and three rays - lay at the bottom of the ocean floor as scavengers, about 50 at each carcass, flocked to the food frenzy.

"There's been lots of research on whale-falls, but we've never really found any of these other large marine animals on the sea bed," lead author Dr. Nick Higgs, from the University of Plymouth's Marine Institute, said, according to BBC News.

Researchers say that carcasses of large animals could provide about four percent of the total food that arrives on the sea floor in this area.

Whale carcasses, they note, usually attract scavengers such as sharks, and then smaller marine creatures like crabs and shrimp-like amphipods pick at the leftovers. This discovery allows for the study of such goings on around other big animal carcasses, and how it compares.

The oil and gas industry recorded a video of the chow down using remotely operated vehicles (ROVs), which were surveying the seafloor around Angola for industrial exploration.

The dead bodies were found between 2008 and 2010 on a one-square-kilometre patch of the sea floor and had been dead for an estimated one or two months.

Higgs commented on the type of scavenging fish at the scene.

"We found three to four different types - but what really dominated were eel pouts. These normally sit around the carcass and wait for smaller scavengers - amphipods - to come along, and they will eat them," he said.

"There were lots of these fish sitting around the carcasses - they seemed to be guarding it."

Researchers did not observe, however, the bone-eating worms (Osedax) typically found at whale carcasses sites.

"Absence of evidence isn't evidence of absence... but the ecosystem does seem different to whale falls," Higgs noted.

Carcass sightings such as these are rare, and it's even rarer that a "graveyard" was found in such a small area.