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Arthropods, 2013, 2(3): 111-125
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Reproductive characteristics of a brachyuran crab, Grapsus tenuicrustatus (Herbst, 1783) (Decapoda: Grapsidae) found in Talim Bay, Batangas, Philippines

Michael A. Clores1, Gliceria B. Ramos2
1Ateneo de Naga University, Naga City, Philippines
2Biology Department, De La Salle University, Taft Avenue, Manila, Philippines

Received 7 March 2013;Accepted 10 April 2013;Published online 1 September 2013
IAEES

Abstract
The study determined some reproductive characteristics of a brachyuran crab, Grapsus tenuicrustatus (Herbst, 1783), one among the most widespread and diverse groups of invertebrates. Results revealed that there were more males (52.94%) than females (47.06%) collected at the study sites with a sex ratio of 1:1.13. Thirty percent (30%) of the samples were ovigerous females. Ovigerous females have the largest caraface length, CL, (31.25 ¡À 1.43) compared with the males (22.14 ¡À 0.726) and non-ovigerous females (26.63 ¡À 1.12). Based on one-way ANOVA, the differences were significant. Difference between non-ovigerous and ovigerous females was also found significant based on t-test for independent samples. There was a non-conspicuous bi-modal size distribution for all the crabs, with non-normal distributions for all crabs and for males, but not when all females or ovigerous females only were grouped together. The size-frequency distributions of males and females are significantly different from each other similar with that observed between the size-frequency of ovigerous and non-ovigerous females. There were more ovigerous crabs belonging to the first year age class (CL = 16 - 33) (53.13 %) than those that belong to the older class (CL = 34 - 43) (46.88 %). Fecundity ranged from 4400 (CL = 16 mm) to 26400 (CL = 43 mm) eggs. Egg volume ranged from 0.40 ml to 2.40 ml, egg diameter from 1.1 ¦Ìm to 5.0 ¦Ìm with an average diameter of 3.170 ¦Ìm and egg count from 4400 to 26400 with a mean of 12684 eggs. Egg number was positively correlated with female size.

Keywords Grapsus tenuicrustatus;brachyuran crab;fecundity;ovigerous;reproductive characteristics.


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