Guardian Nature School Team Contact Blog Project Noah Facebook Project Noah Twitter

A global community of nature enthusiasts
photographing and learning about wildlife

Join Project Noah!
nature school apple icon

Project Noah Nature School visit nature school

Northern Map Turtle, common map turtle

Graptemys geographica

Description:

The northern map turtle gets both its common and scientific names from the markings on its carapace, which resemble contour lines on a map or chart. These lines are usually shades of yellow, tan, or orange, and are surrounded by dark borders, with the rest of the carapace being olive or greyish brown. However, the carapace markings tend to fade as the animal matures, and in older individuals are usually only visible when the shell is wet. The carapace has a hydrodynamic appearance and is broad with a moderately low keel. The rear of the carapace is flared and the rear marginals form serrations. The plastron is yellowish and is marked by a central dark blotch (plastral figure) that follows the sutures of the plastral scutes and fades with age so that many adults lack a pattern all together (i.e., the plastron is immaculate). The head, neck, limbs and tail are dark green with thin yellow stripes, and an oval or triangular spot is located behind each eye. Like other map turtles, this species exhibits extreme sexual size dimorphism; males are 10–16 cm (3.9–6.3 in) in carapace length and weigh between 150–400 g (5.3–14.1 oz), while females are 18–27 cm (7.1–10.6 in) in carapace length and weigh around 0.67–2.5 kg (1.5–5.5 lb). Females have a much wider head than males and this is associated with differences in feeding. Males have a narrower carapace with more distinct keel, narrower head, and a longer, thicker tail. Unlike females, the opening of the cloaca is beyond the rear edge of the carapace. Young map turtles have a pronounced dorsal keel. Hatchlings have a round greyish-brown carapace that is about 2.5 cm (0.98 in) long.

Habitat:

small wetland surrounded by a band of forest/schrubland and some prairie. a larger adjacent lake includes islands that are home to a natural great egret and blue heron rookery.

Notes:

these were far enough away that I couldn't even tell what they were through my 300mm lens. But I saw some movement, so I snapped some shots and sure enough when I cropped and enlarged them was pleased with what I discovered.

Species ID Suggestions



Sign in to suggest organism ID

No Comments

jazz.mann
Spotted by
jazz.mann

Joliet, Illinois, United States

Spotted on Jul 3, 2021
Submitted on Jul 11, 2021

Noah Guardians
Noah Sponsors

Join the Project Noah Team Join Project Noah Team