METHYL FARNESOATE AND THE EFFECT OF EYESTALK ABLATION ON THE MORPHOGENESIS OF THE JUVENILE FEMALE SPIDER CRAB LIBINIA-EMARGINATA

The effect of eyestalk ablation on morphogenesis and levels of methyl farnesoate (MF) in the hemolymph were investigated in juvenile females of the spider crab Libinia emarginata. The ablated crabs had signific antly increased levels of MF in the hemolymph as early as 7 days post- ablation, which continued to increase during premolt. In the intact co ntrols, MF levels in the hemolymph remained low throughout the intermo lt and premolt periods. All ablated animals molted to giant juveniles, while the intact controls molted to the adult form. These results str ongly suggest that there is a period of the molt cycle which is sensit ive to elevated levels of MF in the hemolymph, and that MF has a juven ilizing effect on morphogenesis in L. emarginata and probably in other crustaceans as well.