Printed in Great Britain THE CARDIAC RESPONSES TO SHELL OPENING AND CLOSURE IN THE BIVALVE

• Main Authors: Arctica Islandica (l, A. C. Taylor, Port Erin, Isle Of Man
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1975
• Subjects: Arctica islandica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.543.882; http://jeb.biologists.org/content/64/3/751.full.pdf

Shell closure in Arctica islandica is followed by an exponential decrease in the oxygen tension of the mantle cavity water and is accompanied by an initial increase in heart rate which is followed at lower oxygen tensions by a brady-cardia. Prior to shell opening there is a slight increase in heart rate before any movement of the shell valves can be detected. However, once the shell opens and pumping activity recommences there is a rapid increase in heart rate, often to levels above normal. Perfusion of the mantle cavity with water of high and low oxygen tension resulted in the cardiac responses normally associated with shell opening and closure. Recordings of the POf of the blood in the ventricle, made simul-taneously with cardiac recordings, showed that the changes in heart rate were recorded only after the POg of the blood had changed. These ex-periments suggest that changes in the POf of the mantle cavity water may be primarily responsible for the cardiac responses to shell closure in Arctica.