Friday Find: Greenland Sharks

Scientists from the University of British Columbia have been following the oldest animals alive in unexpected places. Greenland sharks (Somniosus microcephalus) are believed to live several hundred years, and can reach sizes of several meters.

While they are usually found in cold, Arctic waters, the population that the GEERG has been following returns to the Saint Lawrence River every summer, disappearing as cold weather sets in.

Researcher Chris Harvey-Clark says that "all the papers published on the species, including magazine articles, can barely fill two shoeboxes," in part because of the species preference for deep, dark and cold waters. Why they congregate in the river's mouth is unclear.

They are considered scavengers, favoring seal carcasses or pieces of dead whales, though one shark was found with an entire caribou in its stomach. There doesn't seem to be enough food in the river to feed a large population of large carnivores, and the sharks were not known from those waters a few years ago.

I've said before that one of the great challenges facing science today is gathering basic information about the diversity of life on earth. That large sharks could suddenly appear in a heavily trafficked waterway, then disappear as suddenly to points unknown is a sign of how little we know about the most visible parts of the natural world.

At least we know what we want to learn about these sharks. For each such species that we know we should study more there are hundreds that we don't even know exists, let alone anything at all about how it lives and where it goes.

Overfishing nearly eradicated Greenland sharks, which were processed to derive vitamin A long ago. Had that happened, these mysteries and their solutions would have vanished too. We don't know what is being lost in the rainforests that are being cleared and burned, nor in rivers choked with pollution. There are Friday Finds all around us, and there will only be fewer if we aren't careful.