The Displacement Method of Weighing Living Quatic Organisms

IN 1927 a method was devised by which living aquatic organisms can be weighed without removing them from their environment. Two accounts of the method were published in 19381,2, but a much fuller account of the technique was published in 19423 and 19434. In outline the method is very simple since, in the case of a marine animal such as a prawn, it consists of placing it in a suitable density bottle which is otherwise full of sea water and weighing the whole. The exact volume of the bottle and the density of the sea water are readily obtainable, and it is then only necessary to know the exact volume of the prawn to ascertain its weight.