WS 4.6 - Transparent Fish & Aliens Found Under Antarctic Sea Ice

Name:______Date:______Per:______

WS 4.6 - Transparent Fish & Aliens Found Under Antarctic Sea Ice

After drilling through Antarctica's Ross Ice Shelf, scientists have discovered microbes, crustaceans, and even several kinds of strange transparent fish living in water buried under nearly half a mile of ice. As recently as a decade ago, it was thought that nothing could survive beneath Antarctica's massive ice sheets. The water under the ice sheet is around 33 feet (10 meters) deep, and temperatures hover below freezing. The new finds include several kinds of fish that have big eyes, maybe because the animals live in darkness. Some were orange, others black, but the biggest fish of all had translucent skin through which the animal's internal organs could be seen.

"From a biological perspective, we got the first glimpse of life beneath the ice on the fifth largest continent on our planet—a continent that was previously thought to be nothing more than a benign body of ice," says study team member John Priscu, a professor of ecology at Montana State University. The new discoveries come courtesy of the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project, an interdisciplinary collaboration of more than 40 scientists.

After using a hot-water drill to punch through 2,400 feet (740 meters) of ice, the scientists lowered a remote-controlled submersible down the hole. This robot sent back images and video of life below the shelf. It's not clear yet if the new see-through fish represent a new species, but it's likely that they belong to the suborder Notothenioidei. Thanks to a combination of geothermal heat and the pressure created by the ice sheets above, these fish live in water that's perpetually 28°F (-2°C). That means the fish have had to develop numerous adaptations to survive.

"Their evolutionary success is related to key adaptations, such as antifreeze glycoproteins, which prevent their body fluids from freezing at subzero temperatures," said Hanel. As for being able to see their guts, Hanel said the fish are probably translucent as a result of the evolutionary loss of hemoglobin, the protein that makes blood red. This loss of Hemogloben would mean that the fish has a much lower metabolic rate than its warm water relatives. This is a possible adaptation to surviving under the low nutrient conditions found in the sub-ice water.

Finding bug-eyed fish was certainly a happy surprise, but some scientists are even more interested in the microbes. Last August, the WISSARD project colleagues published an article in Nature proving for the first time that microbial life existed beneath the West Antarctic Ice Sheet. The rock eating microbes where extracted from a lake buried a half mile below the surface of the West Antarctic Ice Sheet. This report is a landmark for the polar sciences as well as the science of astrobiology, the search for life on other worlds. In recent years, scientists have come to understand that life can thrive in a much wider range of environments than they once believed, including superheated water at the bottom of the ocean and ice caves in Greenland. That suggests that extraterrestrial life might also exist in places once thought uninhabitable.

This new identification of microbes in subglacial Lake Whillans, a 6-foot-deep, 20-square-mile body of water kept liquid by heat from the bedrock below and friction from glaciers moving over that bedrock "beg the question of whether microbes could eat rock beneath ice sheets on extraterrestrial bodies such as Mars."

The Lake Whillans microbes are chemoautotrophs, meaning they get their energy not from sunlight nor from other organisms that live on sunlight, but rather from chemicals dissolved in the water and contained in Antarctic rock, including nitrites, iron, and sulfur compounds. Given their ability to exist without light or access to organic food sources, the microbes could also be a model for life on Jupiter's ice-covered moon Europa or Saturn's Enceladus.

1. Was this research done in the north pole or the south pole?

1. What are 2 ways freezing water damages cells?

1. How are the fish found under the Ross Ice shelf adapted to survive in the freezing water?

1. How are the transparent fish adapted to survive the low nutrient conditions?

1. What were the primary producers found in Lake Whillans?

1. What was the source of the chemicals for the Lake Whillans chemosynthetic bacteria?