e-ISSN 2231-8542
ISSN 1511-3701

Home / Regular Issue / JTAS Vol. 37 (3) Aug. 2014 / JTAS-0583-2013


Demographics of Horseshoe Crab Populations in Kota Kinabalu, Sabah, Malaysia with Emphasis on Carcinoscorpius rotundicauda and Some Aspects of its Mating Behaviour

Robert, R., Muhammad Ali, S. H. and Amelia-Ng, P. F.

Pertanika Journal of Tropical Agricultural Science, Volume 37, Issue 3, August 2014

Keywords: Carcinoscorpius rotundicauda, horseshoe crab, mating behaviour, population structure, Tachypleus gigas, Tachypleus tridentatus.

Published on:

Survey results of two populations of Carcinoscorpius rotundicauda at a fishing ground and within a protected area were compared so as to establish effects of human activities on the species. Tachypleus tridentatus and Tachypleus gigas were also found in both sites but in substantially less abundance. The operational sex ratios were male-biased at both sites; 5.50 (n = 52) at the fishing ground (Site 1) and 2.58 (n = 68) at the protected area (Site 2). Size distributions at both sites were similar of which females were approximately 16% larger than males. A captive experiment was conducted where pair-forming behaviour of C. rotundicauda was observed for 30 days. Amplexus were most frequently formed when the sex ratio was balanced, lasting for 2.44 ± 2.03 days, and eight days maximum. Female body size and amplex-forming frequency were positively correlated ( r = 0.678, n = 7, p = 0.10), attributable to fitness projected by the phenotype. Solitary males did not exhibit aggression towards paired males, allowing the latter to retain mate exclusivity for considerable periods. Anthropogenic pressures caused an unnatural shift in the population structure of local horseshoe crabs that could lower their reproductive success, making eventual extirpation possible.

ISSN 1511-3701

e-ISSN 2231-8542

Article ID


Download Full Article PDF

Share this article

Recent Articles