Heart and scaphognathite activity in the shrimpPalaemon adspersusRathke

Abstract

The general behaviour of the hean and scaphognathites of Palaemon adspersus was investigated at different oxygen tensions and at different salinities. Compared with other species reported on, the organ activities of P. adspersus show few arhythmic events such as cardiac arrests and scaphognathite apnoeas. Heart rate decreased directly with hypoxia whereas scaphognathite rate increased over the range pO₂ 150-40 mm Hg and rapidly fell at pO₂ levels < 40 mm Hg. Reoxygenation after hypoxia produces an immediate acceleration of organ rates to normal levels. Heart rate was not shown to be salinity dependent - the animals displaying similar organ frequencies when adapted to a wide range of salinities and when subjected to salinity shocks.