by Vince Sheidt
Reprinted from the newsletter of the San Diego Herpetological Society, Vol.25, No.9, September 2003.
Originally published in the SDHS Newsletter, December 1985.
Southwestern Africa’s great Namib Desert is truly one of the earth’s most peculiar environments. Stretching for 12,000 miles along the Atlantic Coast from Angola in the north through all of western Namibia to the Olifanants River in South Africa’s Cape Province. This cold, windy, and al.most rain-free (.5 to 2 inches per year with frequent rainless years) habitat is home for a variety of unique plants and animals. All have adapted in one way or another to the harsh and inhospitable climate. Succulent shrubs and herbs blanket the coastal strip, like many plants and animals here, deriving virtually all of their required moisture from a blanket of omnipresent fog nearly 1000 feet thick. The fog saturates this western part of the desert. Temperature year-round within this belt normally varies only a few degrees between 50 and 60°F. Only along the inland margins do summer temperatures approach typical low-latitude temperature extremes of 80 to 100°F. Large areas of the Namib are completely soilless and lifeless. Soils that do occur are frequently high in saline or otherwise unsuitable for substantial plant growth. But much of the desert is covered with large sand dunes. Individual dunes in this system can extend uninterrupted for 10 to 20 miles and can reach 800 feet above the barren bedrock. Smaller, constantly moving dunes frequently fill the gaps between major dune fields. And it is here in this sandy, wind blown environment that one of the world’s smallest vipers thrives in an amazingly well-adapted manner.
Bitis peringueyi has several common names: Peringuey’s Desert Adder, The Side-Winding Adder, Namib Dwarf Sand-Adder, and others. In many ways, it is similar to our Rattlesnake, Crotalus cerastes. This truly diminutive Bitis normally averages 8 to 10 inches in total length. B. peringueyi is typically a nondescript gray, grayish-white, or beige snake dorsally, with three longitudinal rows of elongate darker blotches. Ventrally, it is uniformly white with or without small dark spots and often with dark reddish brown spots on the sides. About 25% of adults have tail tips which are coal black, the rest having normally pigmented (to match the dorsal coloration) tails.
The characteristic which gives B. peringueyi its most diagnostic and distinctive feature is the presence of dorsally placed eyes. Situated nearly on the top of the head, they give this tiny viper the bizarre appearance of perpetual star-gazing. This is not unlike a flatfish in overall look. This, of course, is principally an aid in hunting. The snake lies buried just beneath the surface of the sand with only its tail-tip and ocular region exposed. When a lizard happens to pass by, possibly having been attracted by the exposed, grub-like tail tip, it is grasped and envenomated until sufficiently quiescent so as to allow easy swallowing.
As one of its common names implies, this species is able to locomote rapidly across blowing sand dunes in a manner similar to Crotulus cerastes. It can climb up slopes in excess of 45 degrees. In order to drink in this rainless environment, the viper flattens its body to collect fog condensation, which forms on its roughly keeled surface.