THE CLAW OF THE TIGER - AN ASSESSMENT OF ITS MECHANICAL SHAPE OPTIMIZATION

Claws of carnivores may be exposed to extremely high loads when prey is taken or during fights with other animals. It is shown in this paper that the concave contour of the claw is a logarithmic spiral and that it is characterized by a constant stress state under "service" conditions. This means that no point is more susceptible to failure than another and furthermore, no superfluous material is contained in the claw. A similar high degree of shape optimization was achieved by a new computer method, CAO (Computer Aided Optimization), which is able to simulate biological growth. The same high degree of mechanical optimization has been found in the claw of the black bear (Ursus americanus), and probably, the same is true for short "bending bars" in biological structures. © 1991 Academic Press Limited.