Bacteria induce settlement and metamorphosis of Janua (Dexiospira) brasiliensis Grube (Polychaeta:Spirprbidae)

Larvae of the spirorbid Janua (Dexiospira) brasiliensis Grube settle on multi-species microbial films grown in laboratory aquaria. Bacteria appear to be responsible for inducing metamorphosis. Larvae of Janua rarely settled on films of the diatom Nitzchia. The larvae settled on pure culture films of bacteria isolated from the green macroalga Ulva lobata, a common natural substratum for Janua (Dexiospira) brasiliensis. Individual bacterial strains varied in their capacity to induce settlement and metamorphosis. Our data suggest that the metamorphic cue is associated with the surface of selected bacterial species.