Search

Heart beats of unrestrained Carcinus maenas L. have been recorded by means of aspiration electrodes. The heart rate shows a clear dependence upon the oxygen content of the sea water under otherwise constant conditions. There is a high degree of correlation between heart rate and oxygen concentration in the range between 0 cm and ca. 6 cm O/I sea water. From this point upwards no further dependence could be found. Very low (beneath 0.5 cm O/I water) and very high (over 12 cm O/I water) concentrations lead to arrhythmia and often to long lasting intervals in the heart beats. It is suggested that this correlation is due to the oxygen-dependent excitability of the neurones generating the beats in the neurogenic hearts of crustaceans. [ABSTRACT FROM AUTHOR]