Thermal Vent Clam ( Calyptogena magnifica ) Hemoglobin

Abstract
A heterodont bivalve mollusk Calyptogena magnifica, from the East Pacific Rise and the Galápagos Rift hydrothermal vent areas, contains abundant hemoglobin in circulating erythrocytes. No other known heterodont clam contains a circulating intracellular hemoglobin. The hemoglobin is tetrameric and has a relatively high oxygen affinity, which varies only slightly between 2° and 10°C. The presence of hemoglobin in the clam may facilitate the transport of oxygen to be used in chemoautotrophic hydrogen sulfide metabolism.