Data from: Thermoregulation as an alternate function of the sexually dimorphic fiddler crab claw

Fiddler crabs are highly sexually-dimorphic. Males possess one small (minor) feeding claw and one greatly enlarged (major) claw; females possess two small claws. The major claw is used to attract mates and for burrow defense but is costly for the male to possess. We tested the hypothesis that the major claw also functions as a thermoregulatory structure, a function that would allow males to spend a greater amount of time on the surface, foraging and attracting potential mates. Fiddler crabs, Uca panacea, were exposed to a source of radiant heat and body temperatures were monitored. Four groups of crabs were tested: intact males, males with the minor claw removed, males with the major claw removed, and females. Males without the major claw increased in body temperature more rapidly and reached higher temperatures than males with the major claw intact, but were similar to females. These results support the hypothesized thermoregulatory function of the major claw. The major claw may function as a heat sink, transferring heat away from the body and dissipating it into the air. Enhanced thermoregulatory ability provided by the major claw may partially ameliorate the energetic costs of possessing such a large claw.招潮蟹（Fiddler crab）具有高度的性别二态性。雄性个体拥有一枚小型（辅助取食的）螯足与一枚显著膨大的雄性螯足（major claw）；雌性个体则拥有两枚小型螯足。该雄性螯足可用于吸引配偶与洞穴防御，但雄性持有该螯足需付出高昂的代谢与生存代价。 本研究验证了一项假说：该雄性螯足同时具备体温调节功能，这一功能可使雄性在地表停留更长时间，用于觅食与吸引潜在配偶。实验对象为帕纳塞招潮蟹（Uca panacea），将其暴露于辐射热源环境中，并监测其体温变化。实验共设置四组受试个体：完整雄性组、切除小型螯足的雄性组、切除雄性螯足的雄性组以及雌性组。 与保留完整雄性螯足的雄性个体相比，切除雄性螯足的雄性个体体温上升更快，且最终体温更高，但其体温变化模式与雌性个体无显著差异。上述结果支持了雄性螯足具备体温调节功能的假说。该雄性螯足或可作为散热结构，将热量从躯体转移并散逸至空气中。该螯足所赋予的更强体温调节能力，可部分抵消拥有该巨型螯足所带来的能量消耗成本。