Body Orientation in Crustacea

Abstract

THERE is, I think, a fallacy which is frequently made in many of the problems dealing with the body orientation of Crustacea. I believe that practically all biologists dealing with this subject have accepted the idea that the position of the centre of gravity is a matter of great importance. Thus, to quote just one of the many statements which have been made along these lines: S. R. Williams¹ says, “A sinking animal, like a lifeless body, always falls with the heavy end downwards.” Lifeless bodies do not sink with the heavy end downwards unless their specific gravity is considerably greater than the liquid in which they are sinking. Not only can this be demonstrated by experiment but also it is in agreement with standard text-book hydrodynamics.