Field Observations of Moulting and Moult Increment in the Red Land Crab, Gecarcoidea Natalis (Brachyura, Gecarcinidae), on Christmas Island (Indian Ocean)

Crustaceana ◽  
2004 ◽  
Vol 77 (1) ◽  
pp. 125-128 ◽  
Author(s):  
Peter Green
Keyword(s):  
Indian Ocean ◽  
Field Observations ◽  
Land Crab ◽  
Christmas Island ◽  
Gecarcoidea Natalis

Phylogeography of the Christmas Island blue crab,Discoplax celeste(Decapoda: Gecarcinidae) on Christmas Island, Indian Ocean

2012 ◽  
Vol 93 (3) ◽  
pp. 703-714 ◽  
Author(s):  
Lucy M. Turner ◽  
J. Paul Hallas ◽  
Michael J. Smith ◽  
Stephen Morris
Keyword(s):  
Indian Ocean ◽  
Habitat Destruction ◽  
Conservation Strategies ◽  
Ecosystem Change ◽  
Anthropogenic Factors ◽  
Genetic Structuring ◽  
Land Crab ◽  
Christmas Island ◽  
Number Of Factors ◽  
The Indian Ocean

The land crab,Discoplax celeste(Gecarcinidae) is endemic to Christmas Island in the Indian Ocean. Due to a freshwater-dependant life history, in which the megalopae migrate from the ocean up freshwater streams to their adult terrestrial/freshwater habitat,D. celesteinhabits only a few isolated locations on the island. This restricted distribution is one of a number of factors which has previously highlighted the vulnerability of this species to outside threats. A number of anthropogenic factors including the introduction of multiple invasive species and habitat destruction have led to drastic ecosystem change on Christmas Island. The aim of this study was to investigate whether the restricted geographical distributions ofD. celestepopulations contribute to significant genetic structuring across Christmas Island, with an objective to inform future conservation strategies for this species on Christmas Island. Fragments of the mitochondrial cytochrome oxidase I gene and the control region were sequenced from 95 individuals collected from all five locations on Christmas Island known to be inhabited byD. celeste. Analyses using analysis of molecular variance revealed no evidence of population sub-structuring, indicating that despite any geographical isolation, there is a single population ofD. celesteon Christmas Island. This lack of population differentiation is probably explained by the oceanic dispersal of larvae, rather than terrestrial migration ofD. celeste. Therefore, based on these results, for conservation purposes,D. celesteon Christmas Island can be considered a single management unit.

Red crabs in rain forest, Christmas Island: removal and relocation of leaf-fall

1989 ◽  
Vol 5 (3) ◽  
pp. 337-348 ◽  
Author(s):  
Dennis J. O'Dowd ◽  
P. S. Lake
Keyword(s):  
Rain Forest ◽  
Forest Floor ◽  
Field Experiments ◽  
Single Species ◽  
Leaf Fall ◽  
Land Crab ◽  
Temporal And Spatial Patterns ◽  
Christmas Island ◽  
Temporal And Spatial ◽  
Gecarcoidea Natalis

ABSTRACTField experiments comparing leaf-fall in the presence and absence of the red land crab, Gecarcoidea natalis, in rain forest on Christmas Island, Indian Ocean showed that, by eating and returning leaves to their burrows, they significantly reduced accumulation of leaf-fall on the forest floor. Red crabs removed 30–50% of the leaf-fall at the experimental sites during the study. Differences in leaf-fall mass between crab-access and exclusion quadrats were positively correlated with the density of foraging red crabs. Red crabs also generated spatial heterogeneity in the distribution of litter on the forest floor by returning litter to their burrows. Leaves lined chambers of 64% of excavated burrows and litter biomass around the entrances was significantly greater than that on off-burrow locations. This was reflected in the significantly higher concentrations of organic matter and nutrients (N, P, K, Ca, Na, and Mg) associated with soils near burrow entrances. These results suggest that a single species, G. natalis, is the major processor of leaf-fall in rain forest on Christmas Island and may affect (1) the temporal and spatial patterns of nutrient availability and (2) the diversity and biomass of the litter fauna.

The systematics of land crabs of the genus Gecarcoidea and recognition of a pseudocryptic species, G. humei, from the eastern Indian Ocean (Crustacea : Decapoda : Gecarcinidae)

2017 ◽  
Vol 31 (4) ◽  
pp. 406 ◽  
Author(s):  
Joelle C. Y. Lai ◽  
Hsi-Te Shih ◽  
Peter K. L. Ng
Keyword(s):  
Indian Ocean ◽  
Morphological Characters ◽  
Eastern Indian Ocean ◽  
Valid Species ◽  
West Pacific ◽  
Land Crab ◽  
Christmas Island ◽  
Extant Species ◽  
Land Crabs ◽  
The Family

The gecarcinid genus Gecarcoidea H. Milne Edwards, 1837 is currently represented by two species from the Indo-West Pacific – the widely distributed purple land crab, G. lalandii H. Milne Edwards, 1837, and the red crab endemic to Christmas Island, G. natalis (Pocock, 1889). One species, G. humei (Wood-Mason, 1874), described from the Nicobar Islands, has had a confused taxonomic history, but was treated as a junior synonym of G. lalandii by Türkay (1974) in his revision of the family. In this study, using molecular as well as morphological characters, we show that G. humei is a valid species. Gecarcoidea lalandii and G. humei have distinct non-overlapping distributions throughout much of their range, with G. lalandii occurring in most of South-east Asia and the West Pacific, while G. humei is known only from the eastern Indian Ocean. On Christmas Island, in the eastern Indian Ocean, however, all three species are present. As a result, Christmas Island is the only locality where all extant species of Gecarcoidea are found. The three species can also be separated by differences in live colours and patterns, as well as proportions of the carapace, male abdomen, ambulatory legs and third maxillipeds, and details of the orbits and male first gonopods.

EXERCISE IN THE TERRESTRIAL CHRISTMAS ISLAND RED CRAB GECARCOIDEA NATALIS - BLOOD GAS TRANSPORT

1994 ◽  
Vol 188 (1) ◽  
pp. 235-256 ◽  
Author(s):  
A Adamczewska ◽  
S Morris
Keyword(s):  
Gas Transport ◽  
Lactate Production ◽  
Circulatory System ◽  
Indirect Evidence ◽  
Blood Gas ◽  
Christmas Island ◽  
Exercise Period ◽  
Gas Measurements ◽  
Gecarcoidea Natalis ◽  
O2 Delivery

The respiratory and circulatory physiology of the terrestrial Christmas Island red crab Gecarcoidea natalis was investigated with respect to exercise in the context of its annual breeding migration. Red crabs were allowed to walk for predetermined periods of up to 45 min. During this exercise period, blood gas measurements were made on venous, pulmonary and arterial samples to assess the function of the lungs in gas exchange and the performance of the circulatory system in gas transport and to determine the role and importance of the haemocyanin. The lungs of G. natalis were very efficient at O2 uptake, pulmonary blood being 80­90 % saturated throughout the 45 min exercise period. The maximum O2-carrying capacity was 1.1 mmol l-1, and haemocyanin (Hc) delivered 86 % of oxygen in resting crabs and 97 % during exercise. Oxygen delivery to the tissues was diffusion-limited during exercise. Indirect evidence, from the changes in haemolymph pH during transit through the lungs, suggested that the lung is the site of CO2 excretion. The Bohr shift was high at high pH (pH 7.8­7.5, phi=-1.23) but decreased at low pH (pH 7.1­6.8, phi=-0.48). The decreased Hc affinity for O2 during the exercise period facilitated O2 delivery to the tissues without impairing O2 loading at the lungs. The decrease in pH was sufficient to explain the change of affinity of Hc for O2 during the exercise period. The marked acidosis (0.8 pH unit decrease) was largely metabolic in origin, especially during sustained locomotion, but less than could be predicted from concomitant lactate production.

The order Zoraptera (Insecta) from Christmas Island, Indian Ocean

1995 ◽  
Vol 9 (2) ◽  
pp. 243 ◽  
Author(s):  
TR New
Keyword(s):  
New Species ◽  
Indian Ocean ◽  
Christmas Island ◽  
Insect Order ◽  
A New Species

A new species of Zorotypus Silvestri, Z. lawrencei, sp.nov., is described from female specimens collected on Christmas Island, marking the first species of the insect order Zoraptera from an Australian territory.

40 Ar/ 39 Ar geochronology and the paleoposition of Christmas Island (Australia), Northeast Indian Ocean

2015 ◽  
Vol 28 (1) ◽  
pp. 391-406 ◽  
Author(s):  
Rajat Taneja ◽  
Craig O'Neill ◽  
Mark Lackie ◽  
Tracy Rushmer ◽  
Phil Schmidt ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Christmas Island ◽  
Ar Geochronology
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