Graptemys


Graptemys is a genus of aquatic, freshwater turtles, known commonly as map turtles or sometimes sawback turtles, which are endemic to North America.

Geographic range

in the genus Graptemys are found throughout the eastern half of the United States and northward into south eastern Canada.

Description

Graptemys species superficially resemble many other species of aquatic turtles, including sliders and cooters. However, they are distinguished by a keel that runs the length of the center of the carapace. In some southern species, the keel can result in vertebral spines, resulting in the map turtle's other common name — "sawback". They also typically grow to a smaller size at maturity. They are given the common name "map turtle" due to the map-like markings on the carapace. Map turtles are known for intricate head markings and strong sexual dimorphism with mature females twice the length and 10 times the mass of mature males.

Feeding morphology

Females of all map turtle species can be partitioned into three groups based on head width and corresponding ecology and phylogeny.
  1. Microcephalic females are narrow headed, sympatric with a broader headed species, and consume few mollusks. Microcephalic species include yellow-blotched, black-knobbed, ringed, Ouachita, and Sabine map turtles.
  2. Mesocephalic females have moderately broad heads and tend to eat mostly mollusks along with softer bodied prey. Mesocephalic species include Cagle's, northern, false, Mississippi, and Texas map turtles.
  3. Megacephalic females have exceptionally broad heads, and feed almost exclusively on mollusks. Megacephalic females include Barbour's, Escambia, Pascagoula, Pearl River, and Alabama map turtles.
Males do not fit neatly into the three groups describing head width, with differences in head width likely not influencing diet.
Due to these differences in head size and jaw strength, females tend to eat much larger prey than the males such as snails, clams, and crayfish whereas the males eat insects and smaller crustaceans.

Courtship behavior

Adult Graptemys males have greatly elongated claws on the front feet, which are used in courtship behavior. The male faces the considerably larger female and "fans" her face, vibrating his foreclaws against her head to induce her to cooperate in mating.

Longevity

Average life expectancy of map turtles ranges from 15 to 100 years, depending on species.

Pet trade

Throughout the pet trade, Mississippi, common, and Ouachita map turtles were bred and hatched out by the thousands in the 1970s. Various other turtles were available, but as the salmonellosis Four-inch Law was established, map turtles and others slowly decreased in popularity. Today, these same three still hold the title for most common among the pet trade. Other species being captive-bred more often include the Texas map turtle, Cagle's map turtle, and the black-knobbed map turtle. Some harder-to-find map turtles include the yellow-blotched map turtle and the Pearl River map turtle.

Species

The following species and subspecies are recognized as being valid.
Nota bene: A binomial authority or trinomial authority in parentheses indicates that the species or subspecies was originally described in a genus other than Graptemys.