Riftia pachyptila and Tevnia jerichonana from the East Pacific Rise
Riftia pachyptila, the giant tubeworm, is found at all known vent sites along the East Pacific Rise and the Galapagos Rift. Tevnia jerichonana is also found in the East Pacific Rise from 13N to 21S. These worms are entirely dependent on sulfur-oxidizing, symbiotic bacteria that supply them with energy. Both these species of tubeworms are thought to be early colonizers of vent sites (Lutz et al 1994). The fact that these tubeworms are very common and are early colonizers may explain their high levels of genetic diversity. The high rates of extinction and recolonization that deep-sea mussels and clams experience may reduce their genetic diversity.