The Otherworldly and Elusive Life Beneath Antarctica's Ice
While renowned for the penguins, Antarctica is perhaps equally well known for what it doesn’t have: basically, anything else.
Considering the frigid, desert-like expanse of Antarctica, the long held assumption of scant biological diversity is unsurprising. For a long time, based on what researchers and explorers could see, this seemed true. Take flowering plants for example. The United States has approximately 16,500 different species. Antarctica? Only two–and the Antarctic pearlwort and hair grass are hardly bouquet-worthy.
“Most people think of the continent as a vast, icy waste,” said Steven Chown, lead author of a review article on recent advances in Antarctic biology published last week in Nature. Regarding the myth that the chilly continent lacks life, Chown said last week, “That’s simply not true.”
Historically, biological research in Antarctica has focused on organisms that are easy to see: the metazoans. This catchall group consists of all multicellular animals (with the exception of sponges). Early explorers and researchers didn’t document much other than penguins and seals roaming the South Pole. As such, Antarctica got a reputation for being “depauperate,” a harsh sounding word used by ecologists to denote a region lacking a wealth of different species.
These initial surveys short-changed Antarctica’s true diversity. Life on the South Pole is comprised of more than just colonies of the famous tuxedo-wearing metazoans. To catch a glimpse of this diversity, it was necessary to look deeper, literally. The really exciting critters are either far beneath the ice in the abyssal ocean or too small to see with the naked eye, and in some cases, both.
Life Beneath the Ice
Deep in the Southern Ocean, miles away from subzero winds that swirl around the surface, several thousands of unknown, unexpected, and ancient species call the abyssal waters home.
For example, a recent survey of the deep Weddell Sea added 700 new species of isopod to the roughly 4,500 previously documented marine species. These Antarctic isopods are related to the backyard roly-polys captured by kids, except some of these benthic species are as big as a cat.
The benthos in the South Pole is markedly different from deep sea environments in other locales, too. Hydrothermal vent communities are typically thought to select for bivalves and polychaete worms. The review cited the findings of a 2012 survey of vents in the East Scotia Sea. What these researchers found during dives to the pitch black benthos 2,500 meters below the surface could give vibrant tropical reefs a run for their money.
Antarctic vents teemed with organisms not seen at other vents: anemones waved their arms languidly in the still water, snails with spiraling, striated shells inched along, pastel sea stars punctuated the inky terrain, and yeti crabs waved back with their furry forearms. The researchers even glimpsed a ghost-white octopus.
Back on the surface of the ice, the biological diversity can only be appreciated with the aid of a microscope. Hundreds of species of moss and lichen and indisputably adorable tardigrades, also known as moss piglets, thrive in this invisible world. Genomic surveys have also shown that microbial communities are more diverse than previously estimated. Going smaller still, a recent study discovered that Antarctica is host to the most diverse viruses ever seen in aquatic systems.
The unique biodiversity of Antarctica has been shaped by the interplay of isolation and evolution. Chown and co-authors cite a study on acorn worms as an example. These worms have been inching around the Ross Sea relatively unchanged for 500 million years. To put that in perspective, hominids have only been around for 7 million.
Now that scientists have a better handle on the breadth of life in Antarctica, the next question is how it will fare in the future. “How this unique biodiversity will respond to the globally changing climate is unknown,” said Craig Cary, who is a co-author on the review.
For now however, scientists hope that calling to attention the unique diversity of life in Antarctica will help fuel future conservation efforts.