As a marine biologist with the Monterey Bay Aquarium Research Institute, Shana Goffredi has seen extraordinary things. But even she was startled by what the cameras of the remotely operated vehicle Tiburon showed her almost two years ago. Lying 2,891 meters deep in the Monterey Submarine Canyon was a fuzzy red whale. The whale’s carcass was covered with segmented worms, their red plumes creating the chenille effect. The worm, Goffredi told a conference last year, proved to be not just a new species but a new genus, one found only on the sunken bodies of dead whales.
That wasn’t all. Lacking a mouth or gut, the worms had rootlike structures that extended into the whale’s bacteria-packed bones. Whalebone, as I can attest from handling the skull of a beached dolphin, is rich in oil that lingers after the animal’s death. The bacteria feed on the oil and produce carbon compounds that nourish the worms. It’s a symbiotic partnership, a food chain unique to the undersea bonanzas known as whale falls.
As with many deep-sea phenomena, we’ve known about whale-fall ecology for only about a decade. Marine biologists speculated that a dead whale would represent a significant input of food to seafloor ecosystems, but no one knew how this was exploited. Then, in 1988, divers in the submersible Alvin discovered a large baleen whale carcass at 1,240 meters in the Santa Catalina Basin that supported a unique community. Mats of bacteria decomposed the oil-rich bones, and the hydrogen sulfide they released supported other bacteria—some free-living, others symbiotes in the gill tissue of clams.
We now know that before the bacteria and clams, the carcass must have fed other sets of consumers. If there is such a science as forensic cetology, its leading figure is Craig Smith, now at the University of Hawaii. Smith towed beached whales out to sea, sank them at depths of 1,000 to 2,000 meters, and revisited the sites to track their fate. “This is a community service,” Smith told a radio interviewer. “A dead whale can be dangerous as well as malodorous: people have been killed by exploding whales.”
Smith found that a whale fall first attracts active scavengers: sharks, hagfish, and rat-sized crustaceans called amphipods. Then come “enrichment opportunists”: dense colonies of worms and mollusks that carpet the organically enriched sediments around the bones. Stage three is the “sulfophilic” community discovered on the Southern California carcass. The entire process may continue for decades.
Biologists were struck by the similarity of whale-fall faunas to those of other enigmatic deep-sea habitats: cold seeps, where hydrogen sulfide oozes from shale and sandstone deposits, and scalding vents that punctuate submarine ridges. Both seeps and vents, at depths never reached by sunlight, have elaborate food webs based not on photosynthesis but chemosynthesis. And vents, seeps, and whalefalls had species in common, although each also seemed to have unique organisms.
Since vents and seeps tend to be both short-lived and widely scattered, it had not been clear how their inhabitants managed to colonize new ones when they formed. The whalebones offered a solution to this puzzle: whalefalls, Smith and others theorized, could be stepping-stones. Assuming an average 25-kilometer distance between carcasses, there would be ample opportunity to disperse to new sites.
Ecologists began to speculate about the impact of the whaling industry on deep-sea biodiversity. Palaeontologists got into the act on Washington’s Olympic Peninsula, where 35-million-year-old whale fossils were found in association with clams similar to living benthic species.
But vents and seeps must have existed long before the mesozoic ancestors of living whales began paddling about in the shallows of the Tethys Sea; remains of vent-specialist organisms date back to at least the Late Cretaceous, 92 million years ago. How would they have dispersed without whalefalls? Ancient marine reptiles could have filled the whales’ role, in death as in life. The ichthyosaurs whose fossils can be seen at a Nevada state park weighed up to 40 tons; some mosasaurs reached 10-meter lengths. That would have been quite a bit of biomass hitting the seafloor. Between the extinction of the sea dragons and the rise of the whales, turtles may have taken up the slack.
You may wonder why anyone cares what happens to a dead whale or how the symbiotic worms and other bizarre creatures make their living in the lightless depths. What practical use could this knowledge have?
Well, how about getting those stubborn stains out of your laundry? Smith and his colleague Amy Baco, now at the Woods Hole Oceanographic Institution, say bioprospectors have shown interest in the bacteria that break down the oil in the whalebones. The enzymes they use—lipases and proteases—work at low temperatures (2-4 degrees Celsius) but remain stable at high temperatures, making them potentially useful in the food-processing and pharmaceutical industries. And one biotech firm, Diversa, has created a number of bacterial clones with cold-adapted lipase activity. It may be just a matter of time until a cold-water detergent, enhanced with whale-carcass enzymes, shows up at a supermarket near you.
