Decorating behavior begins immediately after metamorphosis in the decorator crab Oregonia gracilis

摘要

Behavioral transitions during metamorphosis are critically important for juvenile survival, but often poorly studied relative to morphological and habitat transitions. We used manipulative laboratory experiments paired with scanning electron microscopy imaging to examine the ontogeny of a specific behavior (decorating behavior) during and after metamorphosis in the decorator crab Oregonia gracilis. We found that the hooked setae required for decoration were absent in the megalopa stage, but present in the first instar juvenile stage. The onset of decorating behavior was tightly coupled with this morphological transition: megalopae did not decorate, but first instar juveniles began active decoration immediately. Megalopae and early instar juvenile O. gracilis both displayed strong habitat selection behavior, likely driven by the availability of decorating materials and plentiful hiding places. We also observed an ontogenetic change in decorating behavior between early instar juveniles and adults: first instar juveniles actively decorated with organic debris, rather than any of the offered materials commonly used by sub-adults and adults. Organic debris may be easier for the small juveniles to handle and retain, it may provide better camouflage in microhabitats commonly used by juveniles, or it may act as a partial food cache. The ontogeny of decorating behavior is a useful system for exploring how behavior, morpho logy, and habitat transitions can be coordinated by O. gracilis during metamorphosis.