Larval dispersal of a deep-sea hydrothermal vent bivalve from the Galapagos Rift

The prodissoconch morphology of an unclassified mytilid from a hydrothermal vent on the Galapagos Rift indicates from presence of a planktotrophic larval stage with long-range dispersal capabilities. Recorded abyssal currents are probably sufficient to transport such larvae hundreds of kilometers. It is suggested that one or more aspects of the unusual biological or physico-chemical conditions (such as high microbial densities, elevated water temperatures, and hydrogen sulfide concentrations) encountered at vents, provide a stimulus to larval settlement. Such a behavioral response, perhaps coupled with a "gregarious settling" response, would provide a means of concentrating relatively organisms in an around these restricted, geographically isolated regions.