Active Regulation of Chloride in Metapenæus monoceros Fabricius

Abstract

Metapenæus monoceros is a widely distributed Indo-Pacific prawn often met with in shores and estuaries liable to great variations in salinity. At Madras, it is a common inhabitant of the saline part of the Adyar and Cooum Rivers, and sexually mature as well as post-larval prawns have been obtained in brackish water¹. Dakin² has recently reported that the Australian species of Metapenæus, which is usually known under the name M. monoceros but is believed to be different, breeds in the coastal lakes and estuaries unlike other Penseids. As part of a programme of study on the osmotic regulation in Penæid prawns, we have recently examined the changes in the chloride content of blood in this prawn by employing the micro-modification of the Volhard titration as described by Wigglesworth³. The results obtained appear to be of considerable interest since powers of active regulation of chloride are developed to a very high degree in this prawn (see graph).