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Western Cottonmouth swallowing Western Ribbon Snake (April 1, 2007) Montgomery County, Texas Western Cottonmouth (Agkistrodon piscivorous leucostoma, the large snake in the photo) Highly venomous, Capable of striking at objects within half the length of its body, though the normal strike is no more than 10-12 inches even for mature specimens. BE EXTREMELY CAUTIOUS, DO NOT APPROACH THIS SNAKE; DECAPITATED SPECIMENS REMAIN CAPABLE OF INFLICTING DEADLY BITES. Western Ribbon Snake (Thamnophis proximus proximus, the smaller snake the cottonmouth is preparing to swallow) Harmless, Inoffensive (may bite but the tiny teeth pose no danger) Photos courtesy of Anita M.; text by Jerry Cates The western cottonmouth snake preys on small vertebrates, a few invertebrates, and birds and their eggs. Snakes, salamanders, lizards, and other reptilians make up a considerable portion of its diet, so the sight Anita's children beheld isn't out of the ordinary.
The high resolution image Anita sent made it possible to enlarge the head of the cottonmouth, so that details of that portion of the body can be studied. Note that the head is remarkably flat on top--that's an important identifying feature of this snake, especially when combined with the flat, vertical face on each side of the angular head. Harmless nerodian water snakes have rounded heads, quite unlike this one. Also, notice the pronounced brow-ridge above the eye that forms a protective shelf extending out, laterally; this is another characteristic of the cottonmouth (and some other snakes, but not the nerodians). The cat's eye pupil isn't obvious, because the lower portion of the pupil is indistinct: what IS obvious is that this snake's eye doesn't have a round pupil, which is what you should look for. If you cannot see a large, round pupil, always assume it is a cat's eye instead, just to be safe. And, of course, keep in mind that the cat's eye pupil usually means the snake is venomous.
This cottonmouth seized the ribbon snake at its neck, just behind the head (the portion of the ribbon snake in the upper left quadrant of the photo, above; its eyes are visible on each side of the head).
The body markings of the cottonmouth are often described as obscure, dark, and lackluster. The adult has broad, poorly-defined crossbands, which coloration alternates in gray-brown, dark brown, and black. Each separate band has a light-colored center edged in a darker color, often with white edging that is more pronounced toward the belly. In many cases, as with this one, the crossbands are vaguely similar to the hourglass markings on the southern copperhead (no surprise, since the copperheads and cottonmouth share the same genus). Small dark splotches are often found inside each of these hourglass markings. The scales have indistinct, weak keels, and are arranged in 25 rows at mid-body. In this specimen. It is possible to make out 12-13 rows on the side facing the photographer, as expected (which means the lowest row is adjacent to the belly scales). Many thanks to Anita, the photographer, who took time to send me high-resolution images of this snake so the above details would be of the best possible quality. |
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