Blood respiratory properties in a sea snake and a land snake

Abstract

Haematocrit, haemoglobin concentration, oxygen capacity, haemoglobin-oxygen affinity (Hb-O2) and buffer capacity of whole blood are examined in the banded sea snake, Laticauda colubrina, and the terrestrial black snake, Pseudechis porphyriacus, two ecologically divergent, but phylogenetically close, species. Oxygen capacity is indistinguishable between both snakes and, in general, there is no distinct trend toward high values in diving reptiles. Hb-O2 affinity is slightly higher in the sea snake. The Bohr effect is smaller in sea snake blood but haem-haem interaction is similar in both species. However, it is proposed that moderate differences in the Bohr shift and haem-haem interaction are of little importance to oxygen transport in most reptiles. Plasma bicarbonate is moderately high in both snakes and there is no difference in non-carbonic buffer capacity. In general, the respiratory properties of the blood of sea snakes are not greatly different from those of terrestrial snakes and lizards.