Zoological Studies

Vol. 61, 2022

(update: 2022.10.18)

Unique Behavioral Strategies Adopted by Gravid Ocypode gaudichaudii to Overcome Dehydration Stress while Minimizing Predation Risks

Adeline Y.P. Yong1 and Shirley S.L. Lim1,*

1Ecology Lab, Natural Sciences and Science Education, NIE, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore. *Correspondence: E-mail: shirley.lim@nie.edu.sg (Lim) or shirley.limsl@ntu.edu.sg (Lim).
E-mail: ADELINE-YONG@e.ntu.edu.sg (Yong)

Received 26 February 2022 / Accepted 7 October 2022
Communicated by Benny K.K. Chan

Semi-terrestrial crabs require continual access to water to maintain life-sustaining processes such as circulation and feeding. When they emerge from their burrows during low tide to forage, they face the problem of dehydration as they leave the dampness of their burrows. While foraging above ground, water uptake is elicited through capillary action via the hydrophilic setae near the base of the crab’s body. Extruded eggs that are borne on the abdominal flap of females tend to obstruct the contact of the setae with the wet sediment. The behavioral adaptations of how the gravid female painted ghost crab, Ocypode gaudichaudii, overcomes dehydration stress and minimize predation risks at a sandy shore Playa Venao, Panama was studied by field observations. Comparison of the morphometric measurements of setal tufts between 30 male and 30 female crabs were made to determine if there are morphological adaptations. Analysis of the water uptake behavior from video footages, showed that gravid crabs spent a longer duration on water uptake than crabs that do not carry eggs. Masquerading behavior of a gravid O. gaudichaudii to minimize the detection by predators through freezing movement next to a stone enroute to the lower shore during the day was observed for the first time. There was no sexual dimorphism in the length and width of the setal tufts between the male and female adult crabs. The results of this study provide the first evidence that the water-uptake behavior in gravid O. gaudichaudii is dependent on behavioral adaptations as setal tuft morphology does not differ between the sexes.

Key words: Behavioral adaptation, Masquerade behavior, Setal tufts, Trade-off, Water uptake.

Citation: Yong AYP, Lim SSL. 2022. Unique behavioral strategies adopted by gravid Ocypode gaudichaudii to overcome dehydration stress while minimizing predation risks. Zool Stud 61:81.