Eating Habits of Reptiles ( Part 4)

The alligator snapper is a big, dun-coloured turtle with a three-keeled shell, a huge lumpy head, strong jaws, and musculature that snaps the jaws forward and shut in a lightning-fast strike. Other turtles are able to strike as fast and powerfully, but the alligator snapper has something extra to draw prey within reach. In murky water it looks like a lump of mud or part of the bottom. Its shell and swollen head are generally scarred, eroded, and bearded with algae. Even its eyes are camouflaged by a broad turret of skin that protrudes from the margins of the orbit and partly surrounds the eye, which thus peers out from the depths of a little hole. The device is strikingly like that of the turreted eye of and African chameleon and evidently serves the same general function. The small area of iris visible is spread with black spots, each comparable to the pupil in size, and the excess of these renders the pupil itself meaningless to the observer. At least, that is the way it looks to a human observer and the alligator snapper certainly seems to use this equipment as useful camouflage in feeding. It spends a great deal of its time lying in the murk with its jaws wide open, sometimes still, sometimes with its head swaying slowly back and forth. Look inside its mouth, and if the light is good enough you will see what appears to be the two ends of an earthworm fastened in the middle by a short stalk from the floor of the mouth. The object looks like a worm, and it is quite clearly used as lure to attract fishes into striking distance. It is under complete muscular control, and can be pointed in any direction and extended and contracted in ways strikingly similar to the contortions of an earthworm that finds itself in water. I have never seen a fish grab this bait, but others have. And many times I have seen an alligator turtle open its jaws wide the instant a fish came near, then move the “worm” about suggestively in a way that ought to appeal deeply to any fish not aware that this was actually part of a fish-eating turtle.

The matamata is the most thoroughly inanimate-looking of all turtles-perhaps of all vertebrate animals. Its weird appearance is not simply a misfortune, but rather a clearly utilitarian adjustment to a way of getting food. The matamata not only looks like a pile of debris, but its limbs and grotesquely flattened head are fringed and festooned with shreds and filaments of itself that should, and must, seem to a small fish like edible refuse. In any case, small fishes do come up and nibble and snatch at these projections, and are often quickly sucked in by a remarkable sort of hydraulic trap the matamata uses in place of the strike and jaw hold of the snappers and soft-shelled turtles. The matamata’s jawbones are weak and rubbery, serving as little more than a hoop-like support for the front edge of the greatly distensible mouth and throat. As the head shoots forward at the prey the jaws open wide, the throat distends tremendously, sucking a quick flood of water into the mount, and washing in anything in the neighbourhood that is not strongly anchored.

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