Giant Star Fish and More in Antarctica
Posted on March 21, 2008 Comments (2)
Photo by John Mitchell, New Zealand’s National Institute of Water and Atmospheric Research. Read a great deal about the New Zealand Census of Antarctic Marine Life project: 26 scientists and 18 crew took a 50-day voyage aboard RV Tangaroa in February-March 2008.
Slow growth rates, late reproductive maturation, prolonged periods of embryonic development, and low predation rates that are typical of Antarctic waters contribute to long life-spans for many species and can also result in large size animals. Animal physiology is thought to play a role as well, as those groups that require large amounts of calcium should not, in theory, grow well in Antarctic waters. This is because the calcium carbonate (needed for growth of shells, or starfish ‘tests’) has low solubility in very cold seawater. Yet starfish, which have a calcareous exoskeleton or ‘test’ which needs lots of calcium, can reach much larger sizes than found in New Zealand waters, as seen in [photo].
Another crucial part of the story is that the low sea temperatures allow more oxygen to be dissolved in the sea water than in warmer latitudes. Sea spiders for example are not only larger, but reach more than 1000 times the weight of most temperate species. Amphipod crustaceans in the Southern Ocean are also large; more than five times as long as the largest temperate species.