By James G. Robertson, National Geographic Digital Media
Imagine having to wait for a whale to drop from the sky before you could eat.
At least nine new species of bristleworms that have adapted to feed from the unpredictable food source of dead whales have been discovered by Swedish scientists, according to a release from the University of Gothenburg.
Photo of submerged whale remains: Craig R Smith, courtesy University of Gothenburg, Sweden
The researchers say that some of these previously-undiscovered species are so highly specialized they would have trouble surviving anywhere else. For example, the Osedax worm uses a root system to burrow into the bones and search for food there. Others eat the bacteria that congregate on the surface of the bones.
One whale cadaver "offers the same amount of nutrients that normally sinks from the surface to the seafloor in 2,000 years."
"A dead whale is an enormous source of nutrients," the University of Gothenburg says in its statement. "In fact, one cadaver offers the same amount of nutrients that normally sinks from the surface to the seafloor in 2,000 years, and this is of great benefit to innumerable species: First the meat is eaten by for example sharks and hagfish, then tremendous amounts of various organisms come to feast on the skeleton."
Researchers discovered the new worms, which are related to the earthworm, by placing underwater cameras near whale carcasses they planted on the seafloor 125 meters (410 feet) deep off the coasts of Sweden and California. They retrieved samples and compared the DNA of the worms, and made another discovery: although some worms looked similar, their DNA varied widely.
The difference in DNA suggests that the highly-specialized worms developed from different ancestors and at different times, say the researchers.
Combined with the worms' similar appearances, the DNA also suggests that there may be other wide-ranging species of undersea animals that look similar but in fact are separate species, perhaps making the ocean a more diverse place than previously thought.
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