The swimming of whales and a discussion of Gray's paradox.

The swimming of whales, whose well-authenticated maximum speed is 15 knots or more, is of interest not only to the biologist but also to those who would emulate this performance by artificial means. Fundamental to such a study is a knowledge of the swimming movement, which is not easily observed and has long been disputed. In this paper we give an account of this movement based on two separate lines of evidence: a morphological study (published in detail elsewhere) of the swimming muscles and associated structures of two species of whale; and an examination of a film of living porpoises for which we are greatly indebted to the Marine Studios, Florida, and extracts from which we publish here by their kind permission. Based on this account of the swimming movement it is possible to give a theoretical treatment of the dynamics of swimming, which may guide future experiment. Such a treatment involves a consideration of the drag of moving whales and this in turn leads to a discussion of Gray's Paradox: the big discrepancy which Gray (1936) showed to exist between the power apparently needed to overcome this drag at high speed, and the maximum power to be expected from the swimming muscles. THE SWIMMING MOVEMENT