Sexual dimorphism II
Examples of differences in the appearance of males and females of the same species of arthropods, birds and mammals (compare on successive photos).
Uca tangeri West African fiddler crab
Portugal, distrito de Faro, Alvor.
The genus Uca shows strong sexual dimorphism manifested by extensive development of one of male's claws. Large claw, that represents almost a half of body weight, is used for territorial fighting and for a waving display.