The Fauna associated with the Crinoids of a Tropical Coral Reef: with especial reference to its colour variations

Abstract

[From introduction] Although so much attention has been devoted to the phenomena of mimicry and protective resemblance displayed by land animals, in only one case has the colour resemblances of a marine animal been exhaustively studied. I refer to the classical instance of Hippolyte varians, illustrated by a long series of ingenious observations made by Gamble and Keeble. Briefly stated, the story is as follows: The young Hippolyte is free-swimming and colourless, but it becomes virtually a sedentary animal, anchoring itself to a seaweed or hydroid in the Laminarian zone, on which it finds both food and shelter. The prawn has the power of forming red, yellow, and blue pigments and by altering their relative proportions in the chromatophores it can acquire a green, brown, blue, or red ground-colour, and is thus able to adapt itself to the varied colours of the seaweeds and hydroids. The pigment may be laid down in longitudinal stripes or horizontal bars and in this way a colour scheme can be formed matching whatever seaweed the prawn shelters in. In early life a change in habitat is followed by a readjustment of the pigment altering the colour scheme, but this power is soon lost.