A clump of Bathymodiolus thermophilus seen during the East Pacific Rise Expedition.
Image taken with the submersible Alvin; courtesy of Woods Hole Oceanographic Institution.
B. thermophilus mussels are found at vent sites from 13N to 22S along the East Pacific Rise and along the Galapagos Rift. These mussels depend almost entirely on symbiotic bacteria within their gills to supply energy. Larvae of this species are thought to be actively feeding (planktotrophic) and therefore have high dispersal capabilities (Lutz et al. 1986). Previous studies using mitochondrial DNA and allozyme information have found few differences between individuals at different sites along the East Pacific Rise. Researchers have concluded that high rates of gene flow occur between populations of these mussels throughout their known range (Vrijenhoek 1997).