Pheromones and the gregarious settlement of marine invertebrate larvae

Information on gregarious settlement and metamorphosis of larvae is reviewed for cirripedes, echiuroids, sabellarid polychaetes, and echinoids to determine if the use of adult-derived chemical cues is consistent with the concept of pheromonal communication as applied to other types of animals. Examples of several species of marine invertebrates in which adult-derived chemical cues may be utilized in gregarious settlement and metamorphosis are listed. In appears this mechanism of habitat selection is similar in many respects to communication common in insects and vertebrates where chemicals released to the environment elicit behavioral, physiological, or developmental responses from conspecifics. Evidence is not available to determine if this form of communication in marine invertebrates has specialized beyond adaptive responses of larvae to adult-associated chemicals, to true chemical signalling.