The species on the right is remarkable for the development of long leaf-like processes all over the body, causing the fish to bear a very close resemblance to the seaweed amongst which it dwells.
The Coffer-fishes derive their name from the box-like cuirass in which they are invested. This is formed by numerous closely fitting, hexagonal bony plates, forming a mosaic, and leaving only the fins and hind part of the tail free. This bony case varies greatly in form, in some species being three-ridged, in others four- or even five-ridged; while in some long horns are developed, making the defensive armature still more complex. More than twenty species are known, all confined to tropical and sub-tropical seas.
The Globe-fishes and Sun-fishes constitute the last family of this really extraordinary assemblage. The covering of the body consists either of minute scales or large spines, which can frequently be raised or depressed at will. All the members inhabit tropical or sub-tropical seas, and a few occur in the fresh-waters of the same regions.
The Globe-fishes have short, thick bodies, covered either with small spines, as in the Toad-fish, or very large ones, as in the Porcupine-fish, or Sea-hedgehog. They are remarkable for their habit of filling the gullet with air, and then distending the body to an enormous size. This device enables the fish to escape its enemies; for when so inflated it rises to the surface and floats belly-upwards, and, the inflated portion projecting above the water, the fish is blown along by the wind to more secure regions. The more heavily armed species become still more formidable when inflated, as the spines are then fully erected. Escaping from enemies below by flight, they are thus secure from enemies above by reason of their armature. Globe-fishes have been found floating alive and unhurt within the stomachs of sharks which had swallowed them, and one has even been known to eat its way out through its captor's side, and so killing its would-be devourer! When a globe-fish desires to return to its normal elongated shape, it expels the air from the gullet through the mouth and gills, the expulsion causing a curious hissing sound.
Extremely unlike the foregoing members of the group of comb-gilled fishes, the Sun-fish is nevertheless quite as remarkable in form, looking as if it had undergone the amputation of its hind parts. The singular shape of the other members of the comb- and tuft-gilled fishes are undoubtedly adaptations to avoid enemies, either by rendering the animal inconspicuous, or hurtful by reason of its powerful armature. The form of the sun-fish appears to be an adaptation for the capture of food, as this fish preys largely upon the fry of other fishes which inhabit enormous depths, and consequently can only be obtained by diving. Sun-fishes inhabit the surface-waters, but as divers have few equals.
Photo by W. Saville-Kent, F.Z.S.] [Milford-on-Sea.
SEA-HORSES.
Attaching themselves to marine plants by twisting their tails around them.
