Functions of invertebrate hemoglobins with special reference to adaptations to environmental hypoxia

Abstract

The oxygen-binding properties and some associated structural features of invertebrate hemoglobins (Hb) are reviewed together with the environmental conditions (particularly in stressful habitats) that influence oxygen-binding functions in nature. Compared to the vertebrates invertebrate Hbs display a spectacular variation in functional properties, which is manifest within the major systematic groups of animals and within the different histological and molecular categories of the pigment. This variability is seen primarily to represent adaptations to the wide range of environmental conditions to which Hb-bearing invertebrates are subjected in nature but also to reflect certain organismic functions, which determine the internal conditions under which the Hbs work in life. These adaptations appear to be uniquely directed towards optimizing the transfer of oxygen from the environmental source to the mitochondrial combustion sites. The immense structural and functional complexity of invertebrate Hb systems may well compensate for a decreased organization at the organ level compared to that in vertebrates shifting more of the regulatory burden to the molecular level. © 1980 by the American Society of Zoologists.