Nasal Salt Excretion and the Possible Function of the Cloaca in Water Conservation

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Science  06 Dec 1963:
Vol. 142, Issue 3597, pp. 1300-1301
DOI: 10.1126/science.142.3597.1300


Secretion of concentrated salt solutions from the nasal region was observed in several terrestrial birds and reptiles. In the secreted fluid potassium usually exceeded sodium concentrations, with chloride and bicarbonate as the major anions. It is suggested that the extrarenal excretion of salts is related to the reabsorption of water in the cloaca, that it is necessary for the production of urine with a particularly low water content, and perhaps was prerequisite for the evolution of efficient cloacal water conservation.