page_title: McMurdo Sound
section_title: Life below the ice
hierarchical_section_title: McMurdo Sound / Life below the ice
caption_attribution_description: English: Research diver Dug Coons reaches towards a jellyfish, one of the varieties of sea life that thrive in the -1.5 degree centigrade salt water of McMurdo Sound. Français&#160;: Un chercheur tend la main vers une méduse, l'un des organismes qui vit dans l'eau -1,5ºC du Détroit de McMurdo.
context_page_description: McMurdo Sound and its ice-clogged waters extends about 55 kilometres long and wide. The sound connects the Ross Sea to the north with the Ross Ice Shelf cavity to the south via Haskell Strait. The strait is largely covered by the McMurdo Ice Shelf. The Royal Society Range rises from sea level to 4,205 metres on the western shoreline. Ross Island, an historic jumping-off point for polar explorers, designates the eastern boundary. The active volcano Mount Erebus at 3,794 metres dominates Ross Island. Antarctica's largest scientific base, the United States' McMurdo Station, as well as the New Zealand Scott Base are on the southern shore of the island. Less than 10 percent of McMurdo Sound's shoreline is free of ice. It is the southernmost navigable body of water in the world.
  Captain James Clark Ross discovered this sound, which is about 1,300 kilometres from the South Pole, in February 1841, and he named it after Lt. Archibald McMurdo of HMS Terror. The sound today serves as a resupply route for cargo ships and for airplanes that land on the floating ice airstrips near the McMurdo Station.
context_section_description: A rich sea life thrives under the barren expanse of McMurdo Sound's ice pack. For example, frigid waters that would kill many other fish in the world sustain the Antarctic notothenioids, a bony "ice fish" related to walleyes and perch. The notothenioids feature an Antifreeze protein in their bloodstream that prevents them from freezing. Notothenioids account for more than 50 percent of the number of fish species in the Antarctic coastal regions and 90 to 95 percent of the biomass, according to the National Academy of Sciences for the United States.
  What some sea creatures lack in numbers, they make up for in their visual presentation. McMurdo Sound divers encounter colorful examples of sea life, including bright yellow cactus sponges and green globe sponges. Starfish, sea urchins, and sea anemones are also present. The latter is noted for its wispy tentacles. Large sea spiders inhabit the deeps of the sound and feed on sea anemone, whereas swarms of Antarctic krill flourish in the upper depths of the icy waters. The shrimp-like krill is a key species in the Southern Ocean food chain for sea life ranging from the baleen whale to penguins. The sound is also home to soft coral, whose flexible form allows the creature to bend so as to feed off the ocean floor.
  Antarctic penguins, famous for their waddling walk on surface ice, transform themselves into graceful and powerful swimmers underwater. The emperor penguins' pursuit of squid, fish, and crustaceans leads them to dive as deep as 500 metres (1,600 ft). However, the emperor can go deeper. Scientists have found that the penguin can reach 600 metres (2,000 ft) for short durations. The much smaller Adélie penguin is less ambitious. It feeds underwater for up to two minutes at a maximum depth of 170 metres (560 ft).
  The Weddell seal out-dives even the emperor penguin. The seal can hold its breath for up to 80 minutes and reach a depth of 700 metres (2,300 ft) (Underwater Field Guide to Ross Island & McMurdo Sound). Scientists diving in McMurdo also encounter the leopard seal, and crabeater seal. The many-storied leopard seal is a ferocious predator that preys on warm-blooded animals, such as other seals and penguins, whereas the more sedate crabeater uses its unusual multilobed teeth to sieve krill from the water.
  Seals have a natural enemy in the orca or killer whale of McMurdo Sound. The killer whale's voracious appetite leads it to consume up to 227 kilograms (500 lb) of food daily. The orcas feature black and white coloring, a large dorsal fin up to 1.8 metres (5.9 ft), and enormous strength and size — males can be 8 metres (26 ft). The whales travel in pods of up to 30 individuals and can swim up to 46 kilometres per hour (29 mph).
caption: A research diver reaches towards a jellyfish that thrives in the −1.5 °C (29.3 °F) salt water of McMurdo Sound.
exif: {}