220 MARINE ANIMALS 



Diodoji and Tetrodon). In spite of stony skeleton and stinging cells, 

 these fishes browse on the coral; up to 1 kg. of coral, in rather large 

 pieces, has been found in the stomach of Diodon. 



The competition, amongst so great a number of animals in a 

 limited habitat, is extreme. Protective devices are accordingly evident, 

 more than elsewhere in the rock habitat. All the hiding places are 

 utilized, including the disused holes of the deceased borers. Many 

 forms permit themselves to be overgrown by coral (the snails Magilus 

 and Vermetus, the lamellibranch Coralliophaga, and the annelid Sipun- 

 culus) . Others bore into the coral — sea urchins, boring lamellibranchs, 

 the barnacle Pyrgoma. Crabs mask themselves with sponge. Fishes 

 and cephalopods adapt their colors to the background. Small shrimps 

 and fishes (pomacentrids: Amphiprion, Trachichthys, and Psenes) 8 * 

 seek protection among the stinging tentacles of sea anemones {Stoichac- 

 tis and others) , which they resemble in coloration, even seeking shelter 

 in the enteric cavity. Trigger fishes lock themselves into crevices. The 

 bright colors of some reef fishes may be interpreted as warning colora- 

 tion; many such fishes are actually poisonous. This may also be the 

 case with the opisthobranch snail Bulla, whose emerald green color, 

 with orange spots, as well as its unpleasant musk-like odor, indicate 

 its unpalatability. The riot of color and pattern displayed by coral 

 reef fishes may be due in part to the presence of rich food supplies 

 and innumerable places of refuge which permit colors to vary relatively 

 unchecked by natural selection. 



The richness of the reef fauna is not everywhere the same. The 

 Tuamotu Archipelago, farthest east toward the open Pacific, shares 

 the poverty of the latter. The number of species of corals is smaller 

 than elsewhere in the same latitudes, and the accompanying fauna is 

 similarly impoverished. The fleshy alcyonarians are notably absent, 

 and the gorgonians poorly developed; there are few sponges; and the 

 Tridacna of 15 to 45 cm. are dwarfs in comparison with those of 

 Queensland. 85 Gorgonians and alcyonarians are noticeably absent in 

 Tahiti also. The rich fauna of Indo-Pacific fishes reaches its maximum 

 in the East Indies, and is much reduced in number of species in eastern 

 Polynesia. The total effect of a coral reef is overpowering in its wealth 

 of life and splendor of color. The Dutch refer to them in the East 

 Indies as "gardens." Haeckel speaks of "fascinating coral groves, 

 where every animal becomes a flower." 



In spite of many common characters, the general appearance of 

 the reefs is not everywhere the same. While the reefs at Tur (Red 

 Sea) are marked by the predominance of warm colors, yellow, orange, 

 red, and brown, green is the dominant tone in the coral gardens of 



