Larval metamorphosis of Phestilla spp. in response to waterborne cues from corals

Many marine invertebrates depend on their larvae for dispersal and to settle and metamorphose in the appropriate habitat for adult survival, yet the mechanisms of habitat selection remain poorly understood. In Hawaii, the nudibranch Phestilla sibogae only feeds on Porites compressa and requires a water-soluble cue from this coral for metamorphosis. On Guam, we tested three different species of Phestilla to determine if their larvae require water-soluble compounds from corals to induce metamorphosis. Larvae of P. sibogae metamorphosed at high rates to waterborne cues from multiple species of corals in the genus Porites. Larvae of Phestilla minor could distinguish among waterborne compounds from different species of Porites, but also had high rates of metamorphosis in filtered seawater and in response to corals that adults did not eat. Larvae of Phestilla sp. 2 could distinguish among water-soluble cues from different species of Goniopora and consistently had the highest rates of metamorphosis in response to waterborne cues released from Goniopora fruticosa. P. minor was the only species studied that did not require waterborne cues for larval metamorphosis.