Sea pigs? Gross or cool?
|New Zealand biologist Sadie Mills holds a Protelpidia murrayi sea pig found off the Antarctic shelf/
Credit Richard O'Driscoll, New Zealand IPY-Census of Antarctic Marine Life
Because of a new Facebook quiz on “Which terrifying creature are you,” people are Googling "sea pigs" like crazy. Sea pig? I have 10 years of biology and ecology education under my belt and an additional 15 years working as a wildlife writer, and I’d never even heard of the things. My first thought when seeing one was, boy, they are butt ugly! However, in doing a bit of research, these weird and wonderful deep sea creatures are utterly fascinating! And even kinda cute. I thought I’d share some of what I learned, much of it gleaned from the Christopher Mah’s Echinoblog.
Sea pigs are a deep sea-dwelling species of sea cucumber; it's real name, or technically its scientific name is Scotoplanes globosa. Sometimes people call a handful of other, similar sea cucumbers seapigs, including the one in the photo, Protelpidia murrayi, which lives in the shallower waters off Antarctica. Sea pigs have several squatty little legs and a giant mouth with which they eat detritus that drops down from the ocean surface. Scotoplanes sea pigs live in the deepest abyss, up to 3.7 miles under the ocean surface. In contrast, the deepest part of the Grand Canyon is only 1.1 miles down! And though scientists know very little about their ecology and behavior, since it’s a bit difficult to study creatures living that far down, they often find them hanging about in great numbers.
One study by Monterey Bay Aquarium Research Institute (MBARI) Postdoctoral Fellow Henry Ruhl found their numbers vary with their size, so when there are a lot of them, they are smaller in size. Their populations can fluctuate from year to year by 100-and 1000-fold! Whether they’re actually social creatures remains unknown. It could be that they’re just so abundant that scientists spot hundreds and thousands of them in the same locale. Sometimes scientists have seen them all facing the same direction… probably due to currents, perhaps trying to get the best shot at the falling ocean detritus goo that they eat. Below is a Scotoplanes globosa, alive and walking on the deep abyssal plain of the ocean. Weird, creepy, and cool, all in one, don't you think?
Scientists have found sea pigs in all the world’s oceans including the Southern Ocean off Antarctica. The region has been the site of multiple recent studies, including the 2005 through 2007 Antarctic Benthic Deep-Sea Biodiversity Project, or ANDEEP, a German-led international study of the Drake Passage, Scotia Arc and Weddell Sea, and marine censuses of the two poles as part of the International Polar Year which technically ran from March 2007 through March 2008 to advance our scientific understanding of how climate interacts with the poles. During that work, hundreds of new species were collected from New Zealand's Antarctic waters in the Ross Sea, including gigantic sea stars and sea spiders the size of dinner plates. One cool finding is that although in most oceans, biodiversity decreases with depth, in the Southern Ocean near Antarctica they find the opposite trend. There are a bunch of sea pig photos here, at Denmark's Galathea expedition website (text is in Spanish, though). MBARI scientists, including Ken Smith, have studied changes in the benthic (bottom-dwelling) "megafauna" off the coast of California for decades, including sea pigs.
Because the water gets so cold near Antarctica, sea pigs don’t live as deep. Another weird thing is that the sea pigs get parasites, which is not so surprising, but when you see snail shells growing inside their bodies, it’s pretty creepy. Check out Echinoblog for photos. And the last, interesting factoid is that there are sea pig toys - one-inch long replicas that you can find by searching for Kaiyodo seapig. The Japanese are making jellyfish ice cream...I wonder if anyone makes sea pig ice cream?