Remarkable Find: an Underwater 'Graveyard'
Science gets its first view of giant sharks and rays being devoured
By Derek Andersen, Newser User
Posted May 14, 2014 1:24 PM CDT
A whale shark like this one was filmed dead on the seafloor off Angola.   (AP Photo)

(Newser) – Marine biologists have gotten a grisly treat courtesy of remotely operated vehicles surveying the seafloor off Angola for the oil and gas industry: For the first time, the carcasses of large fish—a whale shark and three mobulid rays—and the feeding frenzy they create have been filmed. The researchers note that previous studies on the fate of vertebrate remains below 600 feet "have been restricted to either small porpoise and dolphin carcasses or large whale carcasses," the latter known as "whale falls." Lead author Dr. Nick Higgs explains to the BBC the sudden richness of the evidence—four carcasses across an area roughly a half-square-mile when none had been seen before—by the fact that there is a large amount of sea-life activity in the waters above the seabed, which has been surveyed more "intensively" than most areas because of its industrial uses.

Large carcasses are interesting, the scientists write in the journal Plos One, because otherwise the main food source in depths beyond where sunlight penetrates is "marine snow" consisting of millimeter-long "dead plankton and fecal pellets." These dead large sea creatures could make up 4% of the food available in these environments (this one was three-quarters-of-a-mile below the surface). Four fish species were identified among the remains, including eel pouts, which prey on other fish that come to scavenge. But the "zombie worms" known to flock to whale bones were absent. "The ecosystem does seem different to whale falls," says Higgs.

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Showing 3 of 7 comments
TwoSheds
May 25, 2014 2:26 AM CDT
Once when I was swimming, I saw a fish in the water.
dennis
May 15, 2014 11:04 AM CDT
Just another part of life is played out.
iq145
May 14, 2014 10:43 PM CDT
Quite another underwater graveyard: In November 2008, the Faroese Chief Medical Officers Pál Weihe and Høgni Debes Joensen announced that Pilot whale meat and blubber contains too much mercury, PCBs and DDT derivatives to be safe for human consumption. Dioxin has now been added to the list, and the latest dietary recommendation on the consumption of Pilot whale meat and blubber are: Adults should eat, at most, one meal of pilot whale meat and blubber per month. Girls and women should refrain entirely from eating blubber as long as they are still planning to have children. Women who are planning pregnancy within the next three months, who are pregnant or who are breastfeeding should refrain from eating whale meat. The kidneys and liver of pilot whales should not be eaten. As a result of the health issues, much of the meat is now discarded into the ocean, as the underwater graveyards discovered by Sea Shepherd in 2010 and 2011 have shown. The grind is not a source of food. It is a despicable ritual blood sport. http://www.newscientist.com/article/dn2362-extreme-mercury-levels-revealed-in-whalemeat.html