The Zoological Society's Expedition to the Zambesi, 1927: No. 2. Observations on the Natural History of the Land-Crab Sesarma meinerti, from Beira, with special reference to the Theory of Warning Colours.


  • *The first published results of the Expedition appeared in the Report on the Zoological Society's Expedition to the Zambesi, 1927, Proc. Zool. Soo, 1928, pt. iv. p. 923.


  • 1The crabs belonging to the genus Sesarma show a wide range of variation in habits and in the conditions under which they live. S. meinerti is a species that has largely adopted terrestrial habits. A colony of the crabs was found at Beira, living on dry ground near mangrove-swamps. The habits of the species are described.
  • 2An attempt has been made to show that the colour of S. meinerti has an aposematic function. The vivid colour of the crab, its aggressive behaviour and power of self-defence, its tough physique and well-developed power of regeneration, and the relative freedom from the persecution of enemies in which it lives, all point to this conclusion.
  • 3The boldness of the species and its ability to defend itself from attack have been adopted in response to the requirements of a more or less terrestrial mode of life, and the aposematic coloration is correlated with the exigencies of this habitat; conspicuousness being useful to the ciabs. the origin and development of the warning colours are to be explained by the operation of natural selection.