ZOU, E.; Nicholls State University, Thibodaux, LA: External Features of Several Sexually Abnormal Fiddler Crabs, Uca pugilator

Like other brachyuran crustaceans, fiddler crabs, Uca pugilator, are normally gonochoristic, exhibiting striking sexual dimorphism. Males are characterized by a pair of extremely asymmetrical chelipeds and a narrow abdomen while females typically have a pair of small, identical claws and a broad abdomen, which virtually covers the entire sternum. I report herein five sexually abnormal fiddler crabs, representing four different forms of sexual abnormalities. In one form of sexual anomalies, male-type chelipeds and female-type abdomen occur on the same specimen, suggesting that the endocrine mechanism underlying the occurrence of asymmetrical claw is different from that for the development of male-type pleopods. All these crabs were obtained from the Gulf Specimen Marine Laboratories, Inc., Panacea, Florida. At present, it is still unknown whether there is an environmental etiology behind these sexual aberrations.