Paramoera walkeri
Paramoera walkeri is an amphipod of the genus Paramoera. It lives around Antarctica.
Description
Like all amphipods, P. walkeri are sexually dimorphic: the males may grow up to ; females,. Newborns are approximately. Males mature after 14–15 months, at about 50% their final size. Juvenile P. walkeri are more sensitive to hydrocarbons, such as from oil spills, than older specimens.Distribution
P. walkeri live in the benthic zone of the Southern Ocean, all around Antarctica, down to a depth of. During the early winter, P. walkeri migrate upward to the ice, and many congregate around patches of algae, in such abundance that they nearly cover the underside of the sea ice sheets. They are also found in the sublittoral zone, and the bottom level of other shallow locations around the Antarctic coast.Behavior
As omnivores, they eat phytoplankton, cryophilic flora, and Diphyllobothrium tapeworms, among other organisms, under the top level of ice. During the summer, their metabolism increases by 80% compared to winter levels. Predators include Trematomus borchgrevinki, T. newnesii, T. bernacchii, Notothenia corriiceps neglecta, and Adélie penguins.During a female's second winter, she releases pheromones, picked up by a male's antennae, signaling that readiness to mate. The male then clings on to the female until she molts. The male releases its sperm into the female's Brood [pouch (Peracarida)|marsupium], and the female releases up to 200 eggs. When the sea water becomes diluted, the eggs may swell up, to keep the total salinity around the embryos constant. They develop for four-and-a-half months, then hatch in the marsupium. The brooding young remain there for up to a month.