Level of ecdysteroids in the hemolymph of the freshwater prawn,Macrobrachium rosenbergii (Crustacea: Decapoda) in relation to the phenomenon of cheliped autotomy in males

Ecdysteroid titers were determined in the hemolymph of adult freshwater prawn,Macrobrachium rosenbergii, during various stages of the molt cycle, using radioimmunoassay. A comparison was made between hormone levels in males which undergo normal molt and dominant males of the population which periodically commit cheliped autotomy. The latter is a recently discovered phenomenon whereby a male voluntarily sheds off both its long claws at molt, once the ratio between body length and combined claw length reaches a ceiling level of about 1∶3. Shortly before an autotomizing molt, hormone levels were about three times higher than on the eve of a normal molt.