The deep-sea clam, Calyptogena magnifica, is found in the eastern Pacific Rise from 21N to 22S and along the Galapagos Rift. Their occurrence is spotty; abundant at some sites and entirely absent at others. Like the deep-sea mussel, C. magnifica is also dependent on energy produced by sulfur-oxidizing bacteria in their gills. These clams produce large yolky eggs, leading researchers to predict that this species has limited dispersal capabilities. However, a study using anonymous, single-copy nuclear DNA markers revealed high rates of gene flow, indicating that larvae can disperse effectively throughout their known range (Karl et al 1996).