A Rhumba of Rattlesnakes

". . . the succession of curious adventure wore the impression on my mind of inchantment; at sometimes for a moment I thought it might be a dream."

Prairie Rattlesnake

tan rattlesnake on rocky ground

The Prairie Rattlesnake's Crotalus—"Little Bell"

Listen to the warning:

Borror Laboratory of Bioacoustics, Department of Evolution, Ecology, and Organismal Biology Ohio State University, Columbus, Ohio. All rights reserved.

The members of the Corps of Discovery must have hoped to hear a rattlesnake's warning in time to avoid the strike.

The Company They Keep

Map showing ranges of four species of rattlesnakes

Based on Findlay E. Russell, Snake Venom Poisoning (New York: J. B. Lippincott, 1980), as redrawn in Laurence M. Klauber, Rattlesnakes (Berkeley: University of California Press, 1982), 106-107.

The men saw only a few rattlesnakes while traversing the Columbia Plateau the autumn of 1805 because, Lewis surmised, the season was so far advanced. "Nor do I know," he concluded, "whether they are of either of the four speceis found in the different parts of the United states, or of that species before mentioned . . . the prairie rattler . . . peculiar to the upper parts of the Missouri and it's branches." It is not clear what other species he was referring to, but it is possible that they were the Northern Pacific rattlesnake, now classified as C. viridis oreganus; the timber rattlesnake, C. horridus horridus; and the canebrake rattlesnake, C. atricaudatus (ay-tree-cow-DAY-tus, meaning "tough as steel").

A Curious Adventure

It had been a long, exhausting day, filled with a succession of curious adventures, any one of which might have turned into misfortune instead of enchantment. Meriwether Lewis returned to the camp after dark that night, "much fortiegued, but eat a hearty supper and took a good night's rest." The next morning he awoke to find "a large rattlesnake coiled on the leaning trunk of a tree under the shade of which I had been lying at the distance of about ten feet."

It certainly wasn't the first rattlesnake seen on the trip, but he killed this one, and took time to study it. "They do not differ in colours," he observed, "from the rattlesnakes common to the middle Atlantic states, but considerably in the form and figures of those colours." Actually, he had found a new species, later designated viridis viridis, of the genus Crotalus. Crotalus is Greek for "little bell," referring to the rattly bell with which this reptile warns creatures it deems threatening. The species name, viridis, a form of the Latin word for "green," refers to the greenish-gray tinge around the dark brown markings on the snake's back. The common name for Crotalus viridis viridis is prairie rattlesnake. The similar reptile he had seen back home in the middle Atlantic states could have been one of three species of the timber rattlesnake, C. horridus horridus, the canebrake rattlesnake, C. horridus atricaudatus, or the largest of all rattlesnakes, the Eastern diamondback, C. adamateus, which is said to reach from six to nine feet in length.

On this specimen Lewis counted "176 scuta on the abdomen and 17 half formed scuta on the tale." Herpetologists don't use the term scuta today, but call those parts ventral [belly] scales.  The number of ventral scales corresponds to the number of vertebrae. Those on the tail are called subcaudal—beneath the tail—scales.1 Scutella, properly speaking today, are large, heavy scales found on the back of the rattlesnake's head.2

Where did Lewis learn to count "scuta"? From one of his pre-expedition mentors in Philadelphia, such as Benjamin Smith Barton? From Thomas Jefferson, who was also something of a naturalist? From childhood rambles near his homes in Virginia and Georgia?

Or did he glean it from the reference work published in London in 1764, Owen's Dictionary, which was in their portable library? There, the "Rattle-snake" was described as

a genus of serpents, having scuta that cover the whole under-surface of the body and tail, and having the extremity of the body terminated by a kind of rattle, formed of a series of urceolated [urn-shaped] articulations, which are moveable, and make noise. Of this serpent, there are two species, the greater one with scuta of the abdomen a hundred and seventy-two, of the tail twenty-one; and the lesser rattle-snake, having the scuta of the abdomen a hundred and sixty-five, of the tail twenty-eight. The larger is a very terrible, and at its full growth, a very large serpent, growing to eight feet in length, with a proportionable thickness. . . . This serpent is frequent in the woods of America: the bite is fatal, but it is easy to avoid it, the creature being sluggish, unless provoked, and giving notice before it bites by shaking its rattle.

The lesser species of this serpent grows to about seven feet in length, and in most particulars is like the former one, and its bite is equally mischievious.3

The emphasis on size and fearsomeness reflected the popular fascination during the seventeenth and eighteenth centuries with "charismatic" wild creatures such as this one.

 

1. Information of George R. Zug, National Museum of Natural History, Smithsonian Institution, June 23, 2003.

2. Roland Bauchot, ed., Snakes: A Natural History (New York: Sterling Publishing Co., Inc., 1994), p. 14. Scutellum is a form of the Latin word for "shield"; it is also used in other natural sciences for elements characterized by that shape or function.

3. A New and Complete Dictionary of Arts and Sciences; comprehending all the branches of useful knowledge, with accurate descriptions as well of the various Machines, instruments, tools, figures, and schemes necessary for illustrating them, as of the classes, kinds, preparations, and uses of natural productions, whether animals, vegetables, minerals, fossils, or fluids. &London: Printed for W. Owen, at Homer's Head, in Fleet-street. MDCCLIV, s.v. "Rattle-snake."

Funded in part by a grant from the Montana Cultural Trust