Simultaneous measurement of the rates of heat dissipation and oxygen consumption in marine invertebrates having and lacking hemoglobin

1.1. To determine how animals having and lacking hemoglobin partition their metabolism into aerobic and anaerobic processes at different ambient oxygen tensions, rates of heat dissipation and oxygen consumption were measured simultaneously with a flow-through differential calorimeter/respirometer (design and construction details are provided).2.2. Animals studied were Enoplobranchus sanguineus and Lysilla alba, polychaetes having and lacking hemoglobin in circulating erythrocytes, respectively; Tellina alternata and Tagelus plebeius, bivalves having and lacking cytoplasmic hemoglobin in neuroglia, respectively; and Solemya velum, a bivalve having cytoplasmic hemoglobin and sulfur-oxidizing symbionts in gills.3.3. Differences in metabolic responses to low PO2 were displayed between species having and those lacking hemoglobin.