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Natural HistoryReptiles
 

'Twixt Plated Decks

"All the thoughts of a turtle are turtles,
and of a rabbit, rabbits."
— Ralph Waldo Emerson (1893)

ewis and Clark must have seen a great many turtles along the rivers and streams they followed or crossed, and the hunters may have encountered a few more in the tributaries and uplands away from the rivers, but the two captains, as well as the other journalists, evidently gave them no more than a casual glance.

In lieu of Lewis's promised book on the expedition's results in natural history, Nicholas Biddle managed to assemble one long chapter (Chapter 25, 53 pages) on "Botany and Zoφlogy" of Lewis's descriptive paragraphs. It consisted of 33 plants, 38 animals, 56 birds, 11 fish, 7 crustaceans, and just 4 reptiles — horned lizard, snail, garter snake, and rattlesnake — but not one turtle. It may be, as some writers have speculated, that the explorers didn't come across any turtles or tortoises that they hadn't seen back home.1

On the other hand, from a turn-of-the-century point of view, and considering the American public's thirst for the mystery and wonder of the unknown West, there was nothing about turtles and tortoises that imbued them with the nobility of an elk, the ferocity of a grizzly, the magnificence of a pronghorn — "they are all Keenly made, and is beautiful" — or the clarion call of a meadowlark. Their reputations are safely ensconced in their shells, and "all the thoughts of a turtle are turtles."

Taxonomically, turtles and tortoises belong to the class Reptilla (reptiles) and the order Testudines (turtles), sometimes termed Chelonia (from chelone, the Greek word for tortoise). The shells that enclose their bodies consist of two parts, the upper or dorsal (back) one called a carapace (possibly from the Latin word capa, "cape"), the lower or ventral (abdominal) one called a plastron (an Old French word denoting a breastplate of armor). The carapace is made of bony plates that are fused with the bones of the spine and rib cage. The plastron consists of plates called scutes, which in some species are hinged to enable the turtle to completely enclose its body for protection after retracting its most vulnerable members — neck, head, legs, and feet. The shell also is fire-resistant.

A Bale of Turtles2

Epicurean Soup

Diamonback Terrapin
Northern Diamondback Terrapin
Malaclemys terrapin terrapin (Schoepf, 1793)

ear White Bear Islands, above the Great Falls of the Missouri, on  June 25, 1805, Meriwether Lewis remarked that he had seen "a number of water tarripens [terrapins]." However, those turtles he saw that day in the Missouri River could not have been terrapins because they do not live inland. The Malaclemys terrapin terrapin, which is the species Lewis most likely would have been familiar with, thrives only in the brackish water of estuaries and deep bays along the Atlantic Coast between Cape Cod and the Gulf of Mexico.3 What he most likely saw, say some herpetologists, were painted turtles, Chrysemys picta (see next picture). But if they were, how could Lewis have failed to notice the differences in coloration of the head and neck, which are strikingly obvious, and between the markings on their respective carapaces by which keen-sighted turtles are believed to recognize their relatives? He had proved himself capable of some remarkably subtle comparisons between animals he saw en route, and similar ones he remembered from back home. Consider his treatment of the western meadowlark, for instance.

The generic name, Malaclemys (mal-uh-clem-eez), is from Greek words malakos, "soft," and clemmys, "turtle." Terrapin (tare-a-pin) is a derivation of torope, the Algonquin Indian word for turtle.4

The only predators against which the terrapin's sturdy carapace is utterly ineffectual are humans. During the 18th century they were harvested to provide inexpensive food to slaves. In the 19th century, terrapin soup — concocted of chicken stock, cream, egg-yokes, butter, flour, salt, paprika, half a glass of madeira or sherry wine, and of course terrapin meat — was an epicurean prelude to every festive meal. Despite the enactment of a law by the State of Maryland limiting the seasons when terrapins could be captured in Chesapeake Bay, that gustatory appeal combined with the species' low reproductive rate resulted in the severe decimation of its population. Today, terrapin hunting is more or less strictly controlled by state laws.

Breathless Beauty

Painted Turtle
Painted Turtle
Chrysemys picta (Schneider 1783)

ainted turtles, which are classified under the genus Chrysemys, are the most common aquatic turtles in North America. Their native turf extends from southern Canada to northern Mexico. They often are seen in groups, basking on logs in the sun, sometimes one atop another.

The painted turtle shown above is the eastern species. The specimens Lewis is thought to have mistaken for terrapins would have been the western painted turtle, C. p. bellii (Gray, 1831), which has light green markings on the head and body, and sometimes light yellow lines on the carapace. In any case, apparently he never thought of them as belonging to a separate species, much less a new one.

The name of the genus, Chrysemys, comes from the Greek word khrysos, meaning "golden, yellow or light green," and emys, the Greek word for turtle. The species name (specific epithet) picta is Latin for "painted"; bellii, the designation for this subspecies, is for Thomas Bell, (1792-1880), a dental surgeon and naturalist, who for a time was professor of zoology at King's College, London.

Chrysemys is believed to be the most thoroughly studied freshwater genus in the world. One of the more recent discoveries is that although this is essentially an air-breathing animal, it is capable of spending the long winter months buried in the mud or sand of a stream or pond without breathing air, and thus without oxygen. The bones in its shell produce buffering agents to neutralize the deadly lactic acid that builds up in the blood of any animal that is deprived of oxygen.5

Spiny Softshell Turtle
Spiny Softshell Turtle
Apalone spinifera (Le Sueur, 1827)

ewis reported on May 26, 1805, that on a creek he saw "several softshelled Turtles which were the first that have been seen this season; this I believe proceeded reather from the season than from their nonexistence in the portion of the river from the Mandans hither." He was probably correct. This turtle is known now to spend the months from October to April in a state of dormancy while buried in sand or mud beneath the surface of a stream or pond, but at the beginning of the 19th century spring commenced two to three weeks later than it does now, owing to the continuing influence of the Little Ice Age. Lewis appropriately named the stream "Soft Shell Turtle Creek"; it has since been renamed Bullwhacker Creek.6 On the expedition's return trip, in July of 1806, Clark recognized one on the lower Yellowstone River.

Those specimens probably were western spiny softshells, Apalone spinifera hartwegi. The taxonomic name of the genus, Apalone, comes from the Greek word apalos, meaning "soft"; the Latin word spinifera means "bearing spines or thorns"; hartwegi is Norman Hartweg (1904-1964), curator of herpetology, University of Michigan. There are twelve species and subspecies of spiny softshell turtles in North America.7 Today there is a large population of A. s. hartwegi in the Missouri River basin in Montana. The eastern subspecies is Apalone spinifera spinifera (Le Sueur, 1827).

Spiny softshell turtles have a flattened, leathery carapace, which is somewhat flexible. Those little nodules, the "spines," on the fringe of the carapace are properly called tubercles. Softshells can breathe under water for long periods, their bodies drawing oxygen from the water. At other times, the peculiar-looking nose functions as a snorkle which, extended on its long neck, enables the softshell to breathe fresh air while buried safely in the sand or mud. Their three-clawed feet8 are webbed for swimming, and, as with most other turtles, are tipped with sharp claws to help them climb ashore. Females may grow to between 12 and 17 inches in length; males are smaller.

The female A. spinifera lays up to 38 eggs, sometimes nesting more than once in a season on a sand or gravel bar near water. Offspring that survive predation by raccoons, herons, and fish until they reach maturity, at between 8 and 10 years of age, may live for up to 50 years or more.

Lewis and Clark didn't say whether they ate any of the spiny softshells they found, but the meat is considered not only delicious and nutritious, but also, in China and Southeast Asia, medicinally potent.

Image from: http://en.wikipedia.org/wiki/Spiny_Softshell_Turtle

the terms carapace and plastron were unknown to Lewis and Clark's generation; they entered the herpetologist's lexicon only during the second half of the 19th century. The science of herpetology — from a Greek word meaning "creeping thing" or reptile — slowly took root in the U.S. around the turn of the 19th century, from intellectual seedlings that had recently sprouted in Europe. The name itself first appeared in print during the 1730s as herpetography, "a Description of creeping Things," according to the Oxford English Dictionary. Noah Webster, in his Compendious Dictionary of the English Language, published in 1806, defined tortoise merely as "a genus of amphibious reptiles, covered with a crust," and gave almost the same definition 22 years later in his two-volume American Dictionary of the English Language.

The science of herpetology expanded considerably in depth and scope toward the latter part of the century, and especially during the 1900s, including a great deal of popular interest in sea-turtles owing no doubt to their relatively large size — up to 450 pounds — and their photogenic qualities. Nevertheless, much remains to be learned about Testudines of every species. For instance, although nearly all turtles "bask," little is known about either the causes or the benefits of that conduct. Similarly, much remains to be learned about turtles' aural sense, which seems to be limited to low-frequency vibrations such as boat noises in water or footsteps on land. They lack external ear openings, but have scale-covered eardrums surrounded by bony boxes called otic capsules.

The average swimming speed for most turtles is 10 to 12 miles per hour, and at least one of the larger among the world's 300 species of turtles is capable of streaking through the ocean at a blazing 22 mph. On land, soft-shell turtles are comparatively sprightly in the short run, and some tortoises can sprint at the average walking rate of a human, but most amble along at a much more relaxed pace — say, between .13 and .30 mph, or roughly one city block in an hour.9

That brings up another story. Even though their respective carapaces and plastrons are quite light, the short legs, large feet, and broadly extended stance with toes pointed outward (like those of all footed reptiles), combined with their comparatively slow and deliberate pace, give them the appearance of laboring under a great weight, which may have been the inspiration for the ancient legends among many cultures that their lands were supported on the back of a huge turtle.10

-- Joseph Mussulman, 12/06

1. See Keith R. Benson, "Herpetology on the Lewis and Clark Expedition: 1804-1806," Herpetological Review 3 (1978): 87 – 91.

2. Once the expression for a group of turtles, from a 15th-century Book of Venery, a gentleman's guide to hunting and the good life. James Lipton, An Exaltation of Larks (New York: Viking, 1991), 62.

3. "Diamondback Terrapin," in Chesapeake Bay Program, http://www.chesapeakebay.net/info/diamondback_terrapin.cfm. Accessed December 1, 2006.

4. The original description of this species was written in 1793 by the German botanist and zoologist Johann David Schoepf (1742-1800), from a type specimen sent to him by the Reverend Gotthilf Ernst (1753-1815), of Lancaster, Pennsylvania. In 1844 It was reassigned to the genus Malaclemys by the eminent American naturalist Asa Gray (1810-1888).

Ellin Beltz, Scientific and Common Names of the Reptiles and Amphibians of North America — Explained at http://ebeltz.net/herps/etymain.html. (Accessed December 7, 2006.) This is an extremely useful resource for students (and teachers) of herpetology. It includes translations of scientific names, common names, dates and authors of original descriptions, biographies, and mythological references. It covers salamanders, frogs and toads, turtles, alligators and crocodiles, lizards and snakes of America north of Mexico. It also explains that when the name and date following the binomial are in parenthesis, this signifies that the present genus is different from the genus in the original description.

5. Ronald Orenstein, Turtles, Tortoises and Terrapins: Survivors in Armor  (Buffalo, New York: Firefly Books, 2001), 10.

6. This creek bed, which today dries up during the summer and fall, is in country that Clark, on the same date, described as "the Deserts of America,...as it is deficent in water, Timber & too Steep to be tilled."

7. Beltz, "Scientific and Common Names."

8. Around Lewis's time the official name of this species was Trionyx, meaning three claws.

9. Rachel Shweky, "Speed of a Turtle or Tortoise," in Glenn Elert, ed., The Physics Hypertextbook; An Encyclopedia of Scientific Essays, at http://hypertextbook.com/facts/1999/RachelShweky.shtml. Accessed December 3, 2006.

10. The rich history of turtles and tortoises in popular culture is outlined in Wikipedia at http://en.wikipedia.org/wiki/Turtles_and_tortoises_in_popular_culture. See also Gregory McNamee and Luis Alberto Urrea, A World of Turtles: A Literary Celebration (Boulder, Colorado: Johnson Books, 1997).

Funded in part by a grant from the National Park Service, Challenge-Cost Share Program.


 
From Discovering Lewis & Clark ®, http://www.lewis-clark.org © 1998-2014
by The Lewis and Clark Fort Mandan Foundation, Washburn, North Dakota.
Journal excerpts are from The Journals of the Lewis and Clark Expedition, edited by Gary E. Moulton
13 vols. (Lincoln: University of Nebraska Press, 1983-2001)