Programming of Molting in a Male Fiddler Crab, Gelasimus hesperiae (Crane, 1975): Ecological and Biochemical Approach

In fiddler crabs, molting and its stage wise characteristics remain poorly understood. This study demonstrated the programming of molting in male fiddler crab, Gelasimus hesperiae inhabiting mangroves along estuaries of Kerala, India by adopting ecological and biochemical approach. By the onset of premolt, epidermal retraction and sign of setogenesis was microscopically visible in epipodite matrix of third maxilliped. Hemocyte count in the epipodite matrix was maximum during premolt (D2) stage, then it showed a significant decrease (P < 0.05) as the premolt stage attained late stages (D3/D4). The hemolymph total protein increased significantly from intermolt to early premolt (D0/D1) (P < 0.001) stage, then showed a substantial decrease towards late premolt (D3/D4) (P < 0.05); contrary to this, hemolymph ecdysteroid titre was found maximum (20.67 ± 1.00 ng/mL) at late premolt stages. The recorded average annual molting rate ranged 12.5–68.5%. May–June showed high (>55%) molting rate and least (<15%) in August–September. Season wise difference in molting rate was also significant (P < 0.05). The molting was high, when the rainfall between 0–617.0 mm, salinity 12–34‰ and water temperature 28–30.2°C. Overall results from the present studies provide insights to address the questions how fiddler crabs are adapted to their habitat.