| Paramoera walkeri | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Malacostraca |
| Superorder: | Peracarida |
| Order: | Amphipoda |
| Family: | Pontogeneiidae |
| Genus: | Paramoera |
| Species: | P. walkeri |
| Binomial name | |
| Paramoera walkeri (Stebbing, 1906) | |
| Synonyms [1] | |
Atylus antarcticus Contents | |
Paramoera walkeri is an amphipod of the genus Paramoera . It lives around Antarctica. [2]
Like all amphipods, P. walkeri are sexually dimorphic: [3] the males may grow up to 21.7 millimetres (0.85 in); females, 22.8 millimetres (0.90 in). Newborns are approximately 2.5 millimetres (0.098 in). Males mature after 14–15 months, at about 50% their final size. [4] Juvenile P. walkeri are more sensitive to hydrocarbons, such as from oil spills, than older specimens. [5]
P. walkeri live in the benthic zone of the Southern Ocean, all around Antarctica, down to a depth of 310 metres (1,020 ft). [2] During the early winter, P. walkeri migrate upward to the ice, and many congregate around patches of algae, [6] in such abundance that they nearly cover the underside of the sea ice sheets. [7] They are also found in the sublittoral zone, and the bottom level of other shallow locations around the Antarctic coast. [8]
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. [9] Predators include Trematomus borchgrevinki , T. newnesii , T. bernacchii , Notothenia corriiceps neglecta , and Adélie penguins. [4]
During a female's second (occasionally third) winter, she releases pheromones, picked up by a male's antennae, signaling that readiness to mate. [4] The male then clings on to the female until she molts. The male releases its sperm into the female's marsupium, and the female releases up to 200 eggs. [3] [7] 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. [7] [2] [3]
This species was discovered by Thomas Roscoe Rede Stebbing in 1878, named Atylus antarcticus in 1903, and described as Atylus walkeri in 1906. [10] [1] [11] It was named after Alfred O. Walker, a fellow of the Linnean Society. [10]
The leopard seal, also referred to as the sea leopard, is the second largest species of seal in the Antarctic. Its only natural predator is the killer whale. It feeds on a wide range of prey including cephalopods, other pinnipeds, krill, birds and fish. It is the only species in the genus Hydrurga. Its closest relatives are the Ross seal, the crabeater seal and the Weddell seal, which together are known as the tribe of Lobodontini seals. The name hydrurga means "water worker" and leptonyx is the Greek for "thin-clawed".
Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from 1 to 340 millimetres and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far described. They are mostly marine animals, but are found in almost all aquatic environments. Some 1,900 species live in fresh water, and the order also includes terrestrial animals and sandhoppers such as Talitrus saltator.
The Weddell seal is a relatively large and abundant true seal with a circumpolar distribution surrounding Antarctica. The Weddell seal was discovered and named in the 1820s during expeditions led by British sealing captain James Weddell to the area of the Southern Ocean now known as the Weddell Sea. The life history of this species is well documented since it occupies fast ice environments close to the Antarctic continent and often adjacent to Antarctic bases.
The Reverend Thomas Roscoe Rede Stebbing FRS, FLS was a British zoologist, who described himself as "a serf to natural history, principally employed about Crustacea". Educated in London and Oxford, he only took to natural history in his thirties, having worked as a teacher until then. Although an ordained Anglican priest, Stebbing promoted Darwinism in a number of popular works, and was banned from preaching as a result. His scientific works mostly concerned crustaceans, especially the Amphipoda and Isopoda, the most notable being his work on the amphipods of the Challenger expedition.
Phliantidae is a family of isopod-like amphipod crustaceans chiefly from the southern hemisphere.
Cumacea is an order of small marine crustaceans of the superorder Peracarida, occasionally called hooded shrimp or comma shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans. They live in soft-bottoms such as mud and sand, mostly in the marine environment. There are more than 1,500 species of cumaceans formally described. The species diversity of Cumacea increases with depth.
Corophium volutator is a species of amphipod crustacean in the family Corophiidae. It is found in mudflats of the northern Atlantic Ocean. It is native to the north-east Atlantic Ocean, and has been introduced to the north-west Atlantic.
Gammaridae is a family of amphipods. In North America they are included among the folk taxonomic category of "scuds", and otherwise gammarids is usually used as a common name.
Zykov Island is a small island between Fulmar Island and Buromskiy Island in the Haswell Islands, near Queen Mary Land on Antarctica. It was discovered and first mapped by the Australasian Antarctic Expedition under Douglas Mawson of 1911–14 but mistakenly identified as part of Fulmar Island. Remapped by the Soviet expedition of 1956, it was named for Ye. Zykov, a student navigator who died in Antarctica on February 3, 1957.
Phronima sedentaria is a species of amphipod crustaceans found in oceans at a depth of up to 1 km (0.6 mi). They are large in size relative to other members of the family Phronimidae. Individuals may be found inside barrel-like homes, created most commonly from the tunics of select species of tunicate, where they rear their young. P. sedentaria is known to employ multiple feeding strategies and other interesting behaviors, including daily vertical migration. The species is also known by the more common names “pram bug” and “barrel shrimp.”
Curnonidae is a small family of sea slugs, nudibranchs, shell-less marine gastropod molluscs, in the clade Euthyneura.
Abludomelita obtusata is a brown colored species of amphipod crustacean. It may grow up to 9 millimetres (0.35 in) long and lacks a rostrum. It lives in marine sediments of any grain size, but with a preference for a mud content of 10%–40%, around the coasts of the southern North Sea.
Nototropis falcatus is a species of amphipod crustacean. It is whitish in colour, with brown patches, and grows to a total length of around 7 mm (0.3 in). It lives on soft sediment such as fine sand at depths of 10 to 50 metres, from northern Norway to the west coast of Ireland, including the North Sea, and as far south as the southern Bay of Biscay.
Stegocephalidae is a little-studied family of amphipods belonging to the suborder Gammaridea.
Themisto is a genus of marine amphipods in the family Hyperiidae. Their distribution is cosmopolitan.
Metapenaeus stebbingi, the peregrine shrimp is a species of marine crustacean from the family Penaeidae. It is native to the Indian Ocean but in the second half of the 20th Century it was found to have invaded the Mediterranean Sea.
Phyllophora antarctica is a species of red alga in the family Phyllophoraceae. It is native to Antarctica where it grows in dim light on the underside of sea ice. Some of it becomes detached and accumulates in drifts on the seabed. Many different organisms live attached to the fronds or among them.
Bathyporeiidae is a family of amphipods in the order Amphipoda. There are two genera in Bathyporeiidae:
Helleria brevicornis, the sole species of the monotypic genus Helleria, is a terrestrial woodlouse endemic to the islands and coastal regions of the northern Tyrrhenian sea. H. brevicornis is of interest due to its endemism, unique ecology and basal position in the suborder Oniscidea.