Ocypode ceratophthalma (Pallas)

Horn-eyed Ghost-Crab (Ocypode ceratophthalma)

The Horn-eyed Ghost-Crab is indigenous to the Indo-Pacific, where it occurs from the coasts of East Africa far into Polynesia, where the animals run about the beaches in search for edible things, including washed up dead fish, or dead sea birds, but also newly hatched sea turtles.

It is a quite large species with a carapace size of up to 8 cm in diameter. It can be distinguished from other related crabs by the eyestalks extending beyond the eyes into long points, those stalks are longer in males, and shorter or almost absent in females.

In Samoa, the species is called avi’ivi’i resp. pa’a.

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ocypode-ceratophthalma-jp

Photo: J. Poupin; by courtesy of J. Poupin

http://decpoda.ecole-navale.fr/index.php
http://decapoda.free.fr

Ptychognathus easteranus Rathbun

Easter Island Crab (Ptychognathus easteranus)

The Easter Island Crab, described in the year 1907, was originally thought to be restricted to the waters around Easter Island, but was later found to occur on other Polynesian islands as well.

The species is restricted to estuaries and shallow stagnant waters, for example tide pools, but regularly enters freshwater streams and thus, is mentioned here.

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References:

[1] Gérard Marquet: Freshwater crustaceans of French Polynesia: taxonomy, distribution and biomass (Decapoda). Crustaceana 61(2): 125-140. 1991

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ptychognathus-easteranus-jp

Photo: J. Poupin; by courtesy of J. Poupin

http://decpoda.ecole-navale.fr/index.php
http://decapoda.free.fr

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edited: 14.02.2017

Macrobranchium lar (Fabricius)

Tahitian Prawn (Macrobranchium lar)

The Tahitian Prawn is a Indopacific species, its native area stretches from the rivers of the coastal regions of East Africa well into Central Polynesia.

The species shows some sexual dimorphism, with the males being larger than the females.

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In Wallis and Futuna the species is cultivated commercially in taro fields.

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On the Cook Islands the species is called koura-vai ti’aka, in Samoa all prawn species, including this one, are named ula vai.

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References:

[1] Gérard Marquet: Freshwater crustaceans of French Polynesia: taxonomy, distribution and biomass (Decapoda). Crustaceana 61(2): 125-140. 1991
[2] N. Mary; A. Dutartre; P. Keith; G. Marquet; P. Sasal: Biodiversité des Eaux Douces de Wallis et Futuna; Mission d’Octobre 2004. Rapport Final, Ministère de l’Outre-Mer 2006

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macrobranchium-lar-sh

Photo: S. Hashizume, 2008

http://jocv183199.web.fc2.com

Geograpsus severnsi Paulay & Starmer

Hawaiian Land Crab (Geograpsus severnsi)

This species was scientifically described in the year 2011.

Subfossil remains of land crabs have been found on the major Hawaiian Islands for many years, but their identity was not clear. Researchers identified the crab as a new species by comparing physical characteristics with specimens from various collections.

The Hawaiian Land Crab is now known to have occured on all of the larger islands in the Hawaiian chain. The species reached a carapace size of about 6 cm and was therefore probably the largest in its genus.

The Hawaiian land crab species vanished at about 1000 A.D., shortly after the arrival of the first Polynesian settlers resp. of the new animals that the Polynesians brought to the islands (chickens, dogs, pigs and rats).

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References:

[1] Gustav Paulay; John Starmer: Evolution, Insular Restriction, and Extinction of Oceanic Land Crabs, Exemplified by the Loss of an Endemic Geograpsus in the Hawaiian Islands. PLoS ONE, 2011; 6(5): e19916 DOI