FISHES AS MESSMATES 171 
afforded by a slender form (/%erasfer) living in the gullet of a 
kind of Sea-Cucumber, which does not appear to gain anything 
by way of return for its hospitality. Some of the giant sea- 
anemones living on the Great Barrier Reef of Australia harbour 
gaily-coloured little fishes belonging to the Perch family, a given 
species of anemone being the home of a particular species of 
fish. The fish-guest (Amphoprion percula) of one such obliging 
zoophyte (Discosoma Kentz) is orange-red in colour, marked by 
three cross-bands of pearly white, these and the fins being 
edged with black. An allied anemone (D. Haddonz) entertains 
a little fish (A. dzcinctus) which differs from its relative in 
possessing two bands only, while the black edging is absent. 
Fig. 1124.—Indian Rock Perch (Minous inermis) with Commensal Polypes (Stylactis minoi) 
The same anemone also extends its hospitality to a red-and- 
white Prawn (Palemon). In these cases the fishes not only find 
a secure shelter, the stinging properties of which ward off 
attack, but also probably filch some of the food of their living 
homes. On the other hand, it is possible, as suggested by 
Saville Kent, who has described the associated animals, that 
the bright tints of the guests serve as “lure colours”, enticing 
animals which serve as food for the anemones. 
The relations just described are occasionally reversed, as when 
a fish serves as a moving home to zoophytes. Alcock describes 
a Rock Perch (A/inous tnermzs, fig. 1124), native to the Indian 
Ocean, as being always more or less encrusted with small polypes 
(Stylactis minoz), which, being of course carried about from place 
to place, have a better chance of getting abundant food than if 
they were attached to a stone or sea-weed. The fish may perhaps 
derive some protection from the stinging properties of its guests. 
