Some aspects of the respiratory physiology of polychaete body fluids - A study in adaptation

Abstract

This thesis comprises a study of the physiological characteristics of the haemoglobins of several worms in relation to their habitats and life-styles.

A method for measuring oxygen-equilibrium in microlitre quantities of whole blood is described. Equilibrium data were determined for the vascular bloods of the polychaetes Cirriformia tentaculata, Terebella lapidaria, Arenicola marina, and Neoamphitrite figulus. Coelomic haemoglobins were studied in T. lapidaria, Notomastus latericeus, Capitella capitata and the echiuroid Thalassemia neptuni. These bloods differed in oxygen affinity (p50) and the shape of the equilibrium curve (N).

Magelona is unique in the annelids in having haemerythrin and some physico-chemical properties are compared with the sipunculid pigment in Golfingia elongata. Some physico-chemical properties of chlorocruorin, a pigment peculiar to polychaetes, were obtained from Sabella penicillus, Mercierella enigmatica, and Pherusa plumosa and their properties compared.

Assumptions of in vivo pH values were critically examined and large intra-and interspecific differences were measured, some being outside the pH range used in Bohr shift studies.

Carbonic anhydrase kinetics of Arenicola marina blood were compared with a bovine preparation. Inhibition with acetazolamide suggested participation in the removal of metabolic CO₂. The enzyme was looked for in several other polychaete tissues using a micro method developed for this study.

The possibility of a storage function of a coelomic haemoglobin was examined in T. lapidaria. Aerial respiration rates in CO₂-free and 2.5% CO₂ atmospheres at several temperatures were determined. The use of CO₂ buffers is thought to be an innovation.

The effect of temperature on the p50's of T. lapidaria, A. marina, and Neanthes virens haemoglobins was analysed according to the van't Hoff integration. No molecular adaptations reducing temperature sensitivity were found.

The emergent theme was that the polychaetes studied were not so much adapted to a range of environmental variables (since they often created their own environment) but rather to a way of life.