VIII 
ORIGIN AND USES OF COLOUR IN ANIMALS 
209 
Professor E. S. Morse of Salem, Mass., found that most 
of the New England marine mollusca were protectively 
coloured ; instancing among others a little red chiton on rocks 
clothed with red calcareous algae, and Crepidula plana, liv¬ 
ing within the apertures of the shells of larger species of 
Gasteropods and of a pure white colour corresponding to its 
habitat, while allied species living on seaweed or on the 
outside of dark shells were dark brown. 1 A still more 
interesting case has been recorded by Mr. George Brady. He 
says: “ Amongst the Nullipore which matted together the 
laminaria roots in the Firth of Clyde were living numerous 
small starfishes (Ophiocoma bellis) which, except when their 
writhing movements betrayed them, were quite undistinguish- 
able from the calcareous branches of the alga; their rigid 
angularly twisted rays had all the appearance of the coralline, 
and exactly assimilated to its dark purple colour, so that 
though I held in my hand a root in which were half a dozen 
of the starfishes, I was really unable to detect them until 
revealed by their movements.” 2 
These few examples are sufficient to show that the principle 
of protective coloration extends to the ocean as well as over 
the earth ; and if we consider how completely ignorant we 
are of the habits and surroundings of most marine animals, it 
may well happen that many of the colours of tropical fishes, 
which seem to us so strange and so conspicuous, are really 
protective, owing to the number of equally strange and 
brilliant forms of corals, sea-anemones, sponges, and sea¬ 
weeds among which they live. 
Protection by Terrifying Enemies. 
A considerable number of quite defenceless insects obtain 
protection from some of their enemies by having acquired a 
resemblance to dangerous animals, or by some threatening or 
unusual appearance. This is obtained either by a modifica¬ 
tion of shape, of habits, of colour, or of all combined. The 
simplest form of this protection is the aggressive attitude of 
the caterpillars of the Sphingidse, the forepart of the body 
1 Proceedings of the Boston Soc. of Nat. Hist., vol. xiv, 1871. 
- Nature, 1870, p. 376. 
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