It is evident,therefore, that elasmobranchs do have the physiological capacity to drink and will do so when there is a requirement to rapidly increase plasma osmolality following transfer from a hypoto a hyper-osmotic medium. Clearly euryhaline elasmobranchs would face such an acute change in environmental osmolality as they migrate from FW to SW and it is probable that these animals would utilise a drinking response as part of their overall osmoregulatory strategy as they enter the marine environment.