Keys to Nature
Key to Calumet Region Turtles

© Alan Resetar - Keys to Nature Project

Key to Calumet Region Turtles
Alan Resetar
Lay people, citizen scientists and natural resource professionals can use this key to identify Calumet Region turtles. A one page field guide to the amphibians and reptiles of southeastern Chicago and northwestern Indiana can be found at Thanks to Jennie Kluse and Bil Alverson for all of their advice and assistance.


Key Structure:
Key to Calumet Region Turtles

1a. Exposed strip of skin widely separating the hard, horny shields
on midline of plastron (belly portion of shell); tiny, fleshy barbels on chin;
two thin, light stripes on side of head of most individuals . . . Common
musk turtle (Sternotherus odoratus)
1b. Exposed strip of skin not separating most of the horny shields
on plastron (one narrow, transverse strip of skin functions as hinge
on plastron in two species) or entire plastron covered with
leather-like skin . . . 2

2a. Plastron hinged . . . 3
2b. Plastron not hinged . . . 4

3a. Carapace (domed shell) keeled along midline in most individuals;
each carapace scute with yellow to orange spots and blotches . . .
Eastern box turtle (Terrapene c. carolina)
3b. Carapace not keeled, each carapace scute with small, light-colored
flecks; bright yellow chin and throat . . . Blanding's turtle
(Emydoidea blandingii)

4a. Snout snorkel-shaped; carapace and plastron soft, flexible and
skin covered; small spines on anterior margin of carapace . . .
Eastern spiny softshell (Apalone s. spinifera)
4b. Snout not snorkel-shaped; carapace and plastron hard; lacks spines
on anterior margin of carapace . . . 5

5a. Plastron small, leaving withdrawn limbs exposed; rear edge of
carapace saw-toothed; tail length at least 40% of carapace
length . . . Common snapping turtle (Chelydra s. serpentina)
5b. Plastron large, completely covering withdrawn limbs; rear edge
of carapace smooth or moderately saw-toothed; tail length less than
40% of carapace length . . . 6

6a. Carapace black with distinct yellow spots; orange or yellow
markings on head . . . Spotted turtle (Clemmys guttata)
6b. Carapace not distinctly spotted . . . 7

7a. Large, dark blotch along plastron midline; carapace
not keeled . . . Painted turtle (Chrysemys picta)
7b. Plastron randomly marked or almost unmarked and without blotch
along midline; carapace keeled or not . . . 8

8a. Carapace distinctly keeled along midline; small yellow spot
behind eye; plastron nearly unmarked . . . Common map turtle (Graptemys geographica)
8b. Carapace not distinctly keeled in medium and large individuals;
typically a large red patch behind eye . . . Red-eared slider
(Trachemys scripta elegans)


Barbel – small, fleshy skin protuberance on chin.
Carapace – top shell of a turtle.
Keeled – raised ridge along the midline.
Plastron – lower shell of a turtle.
Scute – one of the individual horny shields covering a turtle’s


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This page was last modified on: Mon, 27 Sep 2010 15:42:11 -0500.