EFFECTS OF MAGNETIC FIELDS ON REGENERATION IN FIDDLER CRABS

After autotomy, fiddler crabs ( Uca pugilator and U. pugnax) were placed in magnetic fields (in the 100 Oersted range) produced by ceramic plate magnets in such a way that some crabs were in proximity to the N pole, and others to the S pole. Control crabs were several feet away from the magnets. Regardless of the number of limbs autotomized, direction of the field, species, or salinity of the water, crabs in proximity to the S pole regenerated and molted sooner than con trols, and those by the N pole were delayed in relation to controls. Factors such as magnetic effects on enzymatic reactions and ionic flux, orientation of animals within the magnetic field, and production of electric currents in the limb stumps may be involved in these effects. The opposite responses to N and S poles may be due to the opposite direction of the gradient vector. Regeneration of juvenile crabs, and of adult crabs during the summer months, was not significantly affected by the magnetic fields.