Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 30, Number 7;   July, 2003

Venomous and Sublime: The Viper Tells Its Tale

by Natalie Angier

Many New World vipers have elaborate rattles, a posterior shingling of fingernail-like plates that can shake a warning at 50 beats a second.

Whereas most snakes lay eggs, a great majority of vipers give birth to live young, a fact reflected in the family name, taken from the Latin words vivo, meaning live, and partus, birth. Dr. Harry W. Greene of Cornell and his coworkers describe cases of parental behavior among black-tailed and pygmy rattlesnakes that defied all their presumptions.

"We'd expected that after giving birth the mothers would crawl one way and the babies another," Dr. Greene said. "But instead, we'd find a mother basking with her young day after day or guarding the entrance to a burrow while the babies were inside." Once, he said, he saw a little viper start to emerge from its hold, apparently against its mother's better judgment. "She put her head on him and nudged him back inside."

The researchers propose that parental behavior has evolved among some vipers, together with delayed skin shedding. While most baby snakes shed their skins as soon as they are born, viper newborns, which are comparatively larger, do not discard their birthday suits until they are about 10 days old. While they are shedding that skin, their eyes are beclouded, they are susceptible to water loss, and they are extremely vulnerable. Hence the need for a mother's watchful care.

Dr. Randall S. Reiserer of Vanderbilt University in Nashville tenders evidence that vipers can in fact learn from experience and fine tune their hunting strategies to suit new circumstances. He took 10 young massasauga vipers into his laboratory, some from swampy regions of the Eastern United States and others from the Arizona deserts. As a rule. Eastern massasaugas lure fast-moving frogs by giving undulatory wiggles of their tail, which resembles a worm. But when they see a slower-moving lizard, they do not risk a tail nip and instead pursue on their bellies.

Western massasaugas, by contrast, are faced with fast-darting desert lizards. So they use their tails as lures, while they ignore the few frogs in the area as too toxic. Dr. Reiserer showed that despite their different origins Western vipers could learn to hunt like Easterners, with tail wagging for frogs and pouncing on slow lizards, and Easterners could be trained to wag for lizards and eschew frogs.

Beyond behavioral findings, herpetologists also continue to be impressed by viper physiology. Dr. Akira Mori of Kyoto University and his colleagues describe the hypothermal prowess of the hime-habu, a short stout bodied nocturnal viper that does not recoil from the cold, found on Okinawa and other islands of the Ryukyu Archipelago. The hime-habu viper has evolved the ability to continue feeding in spurts from December through March, even when temperatures dip into the 40's. With that capacity, unrivaled among vipers and, possibly, among all snakes, the hime-hibu can take advantage of a rich source of food unexploited by competing reptiles, two species of frogs that gather near mountain streams by the hundreds for a few frenzied days of breeding.

The vipers somehow knew exactly when the frog fest was scheduled and they appeared at the right spot at the right time and then quickly gulped down five or more frogs in an evening. They spend the next couple of weeks digesting the meal, despite the measurable chilliness of their bodies.

The northernmost snake in the world is a viper. which is found in the Arctic Circle, in Scandinavia. The southernmost snake is also a viper, living in Patagonia. The two snakes species that live at the highest elevation in the world are both vipers, one in the Himalayas, another in the mountains of Mexico. Dr. Harvey B. Lillywhite and his coworkers at the University of Florida in Gainesville describe their discovery in a number of viper species of what Dr. Lillywhite has termed "adaptive constipation." They report that, among some of the ground-dwelling vipers, defecation is a shockingly rare event. Gaboon vipers of Africa, for example, will go for a year or more without disposing waste, even as they continue to feed regularly on rodents. Ground dwelling vipers store up so much offal, the researchers calculated, that their body mass ends up being as much as 20% fecal matter, the vast bulk of it concentrated in the posterior. Dr. Lillywhite suggests that a land-based viper retains feces because it is a great ballast. It helps anchor the lower body to the ground and thus enables the snake to strike its head out toward prey with great speed and accuracy. Best of all, feces is metabolically inert. Extra muscle, bone or fat require energy to sustain them, while feces sits there for free. *  CHS Editor's Note: Coral snakes and Black Mambas are not Vipers, but members of the family Elapidae, which also inclues cobras.