ALTERNATE MATING STRATEGIES OF POLYMORPHIC MALES OF LIBINIA-EMARGINATA APPEAR TO DEPEND ON METHYL FARNESOATE

The spider crab Libinia emarginata has six male morphotypes that diffe r with respect to their appearance and reproductive readiness. Large a braded males compete actively for females and have the largest claws a nd reproductive system indices and highest methyl farnesoate (MF) bloo d levels. Smaller abraded males with short claws attempt mating in the absence of large abraded males but employ the alternative tactics of sneak mating and female mimicry when large aggressive males are presen t. Unabraded morphs of any size do not attempt to mate, either in comp etition or in isolation with receptive females. Their MF levels are lo wer (usually one-half that of abraded males) indicating that they are in a state of reproductive diapause. Incompletely abraded males have i ntermediate levels of MF and are moderately active in reproduction. Th ese data suggest that MF may be involved in directing the reproductive behavior of different male morphotypes.