Juvenile Crabs on Purple-stripe Jelly

Crabs, such as the slender crabs seen here (Cancer gracilis), often spend their formative months in association with a jellyfish before assuming a benthic existence.  Chrysaora colorata seem particularly favored by these crustaceans.  It is not unusual to see an older, battle-worn Chrysaora with 50 or more tiny crabs hitching a ride.   Unfortunately for the jelly, the relationship is not totally benign.  The crabs dine on food that the jellyfish has labored to collect, and probably have no qualms about nibbling on delicate gelatinous flesh.  They even can enter the stomach of the jelly without apparent harm.  After drifting for many miles, the juvenile crabs somehow determine that the time is ripe to jump free and begin the perilous journey to the ocean bottom.  These in turn produce the planktonic zoea larvae that seek out gelatinous traveling hosts.    

 All photographs in the JelliesZone © David Wrobel and may not be used or copied without permission!