Document Detail

Ecology and behavior of Gecarcoidea natalis, the Christmas Island red crab, during the annual breeding migration.
MedLine Citation:
PMID:  11441973     Owner:  NLM     Status:  MEDLINE    
The terrestrial crab Gecarcoidea natalis is endemic to the forests of Christmas Island but must migrate each year to the coast to breed. During 1993 and 1995, radio-tracking, mark and recapture, and counting methods were used to establish the routes, walking speeds, direction of travel, and destinations of migrating crabs, as well as crab numbers and distribution. The density of crabs ranged from 0.09 to 0.57 crabs per square meter, which gave a population estimate of 43.7 million adult crabs on the island. During the dry season the crabs were relatively inactive but on arrival of the wet season immediately began their migration. The crabs generally walked in straight lines, and most crabs from around the Island traveled toward the northwest shore instead of simply walking toward the nearest shore. The maximum recorded distance walked by a red crab in one day was 1460 m, but the mean was 680 m per day in 1993 and 330 m in 1995. Comparing the 1993 and 1995 study seasons, there was a 3-week difference in the timing of the start of the migration, but the spawning date was fixed by the lunar phase and took place 17 to 18 days after mating. In 1993, late rain prompted a "rushed" migration and crabs walked directly to their shore destinations; in contrast, in 1995 most crabs made stops of 1 to 7 days during the downward migration. By giving the crabs a chance to feed along the way and minimizing the time that the population was concentrated near the shore, these stops may be important in ensuring that the animals have enough food after the long dry season. Furthermore, this behavior implies that the crabs are able to judge how far away they are from the shore during the migration.
A M Adamczewsk; S Morris
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Biological bulletin     Volume:  200     ISSN:  0006-3185     ISO Abbreviation:  Biol. Bull.     Publication Date:  2001 Jun 
Date Detail:
Created Date:  2001-07-09     Completed Date:  2001-12-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2984727R     Medline TA:  Biol Bull     Country:  United States    
Other Details:
Languages:  eng     Pagination:  305-20     Citation Subset:  IM    
Ocean Research Institute, University of Tokyo, Japan.
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MeSH Terms
Brachyura / physiology*
Emigration and Immigration
Sexual Behavior, Animal*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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