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The Forces Exerted by the Tube Feet of the Starfish During Locomotion

1953; The Company of Biologists; Volume: 30; Issue: 4 Linguagem: Inglês

10.1242/jeb.30.4.575

1477-9145

G.A. Kerkut,

Cephalopods and Marine Biology

ABSTRACT Doubt has existed as to whether the tube feet of a starfish in locomotion act as a system of levers or whether they form a traction system, attaching to the substratum and contracting so as to pull the animal along. This problem has been investigated by recording the forces exerted by a single tube foot. The recording apparatus is described. It is shown that both lever and traction methods can be used according to circumstances. When the starfish is walking on a horizontal surface it is shown that the tube feet certainly act as struts and that they probably also act as levers. When the starfish is climbing upon a vertical surface (or meeting with resistance upon a horizontal surface) the tube feet attach themselves to the substratum and form a traction system.