Paramoera walkeri
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Superorder: Peracarida
Order: Amphipoda
Family: Pontogeneiidae
Genus: Paramoera
Species:
P. walkeri
Binomial name
Paramoera walkeri
(Stebbing, 1906)
Synonyms[1]

Atylus antarcticus
(Walker, 1903)
Atylus walkeri
(Stebbing, 1906)
Bovallia walkeri
(Stebbing, 1906)
Paramoera antarcticus
(Walker, 1903)

Paramoera walkeri is an amphipod of the genus Paramoera. It lives around Antarctica.[2]

Description

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]

Distribution

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]

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.[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]

Taxonomic history

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]

References

  1. 1 2 De Broyer, Claude; Lowry, Jim (2010). "Paramoera walkeri (Stebbing, 1906)". WoRMS. World Register of Marine Species. Retrieved July 27, 2017.
  2. 1 2 3 De Broyer, C., J.K. Lowry, K. Jazdzewski and H. Robert 2007 Catalogue of the Gammaridean and Corophiidean Amphipoda (Crustacea) of the Southern Ocean, with distribution and ecological data. In C. De Broyer (ed.), Census of Antarctic Marine Life: Synopsis of the Amphipoda of the Southern Ocean. Vol. I. Bulletin de l'Institut royal des Sciences naturelles de Belgique van het koninklijk Belgisch Instituut voor Natuurwetenschappen. Biologie 77(suppl.1):1–325 — via Sea Life Base. Retrieved July 27, 2017.
  3. 1 2 3 Ruppert, E.E., R.S. Fox and R.D. Barnes 2004 Invertebrate Zoology. A functional evolutionary approach. 7th Ed. Brooks/Cole, Thomson Learning learning, Inc. 990 p. — via Sea Life Base. Retrieved July 27, 2017.
  4. 1 2 3 Sagar, P. M. (March 25, 1980). "Life Cycle and Growth of the Antarctic Gammarid Amphipod Paramoera walkeri (Stebbing, 1906)". Journal of the Royal Society of New Zealand. Christchurch: Zoology Department, University of Canterbury: 259–270 – via Google Books.
  5. ↑ Alexander, Frances Jane (January 1, 2016). The toxicity of physically and chemically dispersed fuels to Antarctic marine invertebrates (Thesis). National Library of Australia.
  6. ↑ Ferris, J.M.; Burton, H.R.; Johnstone, G.W.; Bayly, I.A.E. (December 6, 2012). Biology of the Vestfold Hills, Antarctica: Proceedings of the symposium, Hobart, August 1984. Springer Science & Business Media. p. 147. ISBN 9789400930896 – via Google Books.
  7. 1 2 3 Sims, D.W.; Southward, Alan J. (September 26, 2006). "Amphipods". Advances in Marine Biology. Academic Press. 51: 243, 259, 289. ISBN 9780080464527 – via Google Books.
  8. ↑ Arntz, Wolf E.; Clarke, Andrew (December 6, 2012). Ecological Studies in the Antarctic Sea Ice Zone: Results of EASIZ Midterm Symposium. Springer Science & Business Media. p. 94. ISBN 9783642594199 – via Google Books.
  9. ↑ Węsławski, Marcin; Opaliński, Krzysztof W. (1997). "Winter and summer metabolic rates of Arctic amphipods. Preliminary results" (PDF). Polish Polar Studies. 24th Polar Symposium, Warsawa: 315. Retrieved July 27, 2017.{{cite journal}}: CS1 maint: location (link)
  10. 1 2 Stebbing, Thomas Roscoe Rede (1906). Amphipoda I. Gammaridea. Vol. 21. Berlin: Friedländer. p. 728 – via Internet Archive.
  11. ↑ Walker, A. O. (1902). "Mr. A. O. Walker on Amphipoda of the 'Southern Cross' Expedition: Genus Atylus, Leach, 1817". Zoological Journal of the Linnean Society. Linnean Society of London. 29: 58 – via Internet Archive.
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