Geoscience Reference
In-Depth Information
Figure 7-16.
Freshly constructed crayi sh burrow
distinguished by a chimney-like structure of mud built
above the ground surface. This is the favored habitat
for Graham's crayi sh snake (
Regina grahamii
). Comb
is
Figure 7-15.
Northern painted turtle (
Chrysemys picta
),
ventral (bottom) view (see Color Plate 7-15). The
brilliant colors form an intricate pattern on the plastron
and bottom edges of the carapace. This species thrives
in shallow marsh pools and eats both plant and animal
foods; adults prefer plants and juveniles are more
carnivorous (Collins and Collins 2006). Photo by S.W.
Aber; central Kansas, United States.
5 inches (12.5 cm) long. Photo by J.S. Aber; wet
meadow in Cheyenne Bottoms, central Kansas, United
States.
∼
the Western massasauga (
Sistrurus catenatus
tergeminus
). Despite the common fear of snakes,
most snake species are relatively harmless and
many are benei cial for humans (Sievert and
Sievert 2006). As carnivores, snakes play impor-
tant roles in controlling overpopulation among
other small animals; they are themselves prey
for still larger predators and, so, are integral
parts in many wetland ecosystems (Collins and
Collins 2006).
Alligators and crocodiles (order Crocodylia;
see Figs. 7-2 and 7-10) are among the oldest
living reptiles with a fossil record that goes back
to the late Triassic, 230 million years ago (Elgin
2004). Many types of crocodilians evolved
during the Age of Dinosaurs ( Jurassic and Cre-
taceous) for terrestrial, fresh-water aquatic, and
marine environments. But only three families
survive today in the suborder Eusuchia
-
Crocodylidae, Alligatoridae and Gavialidae
(gharials). Crocodiles and alligators are wide-
spread in tropical and subtropical environments
of the Old and New Worlds, although gharials
picta
), eastern river cooter (
Pseudemys concinna
),
and red-eared slider (
Trachemys scripta
).
Snakes (order Squamata) are carnivores that
consume a variety of vertebrates and inverte-
brates. The jaw can open widely, and the left
and right sides of the jaw move independently,
which allow snakes to swallow whole prey
animals of considerable size (see Fig. 7-13).
Given the productivity of wetlands, prey is
abundant, and snakes are common. Most snakes
are opportunistic for their diets, but some
species are quite particular about what they eat.
Graham's crayi sh snake (
Regina grahamii
), as
the name suggests, feeds primarily on crayi sh;
it rests in the shade of crayi sh burrows during
hot summer days and retreats into these same
burrows to hibernate in winter (Fig. 7-16).
Rattlesnakes are perhaps the best known of
all venomous snakes; most species inhabit dry
uplands, but some prefer wetlands, such as
