Black-knobbed Map Turtle

Graptemys nigrinoda

Reptiles & AmphibiansIn the app

Their head is small and dark brown with yellow stripes. They have yellow crescents behind the eye facing towards the posterior end of the turtle. The stripes continue on…

How to identify

Their head is small and dark brown with yellow stripes. They have yellow crescents behind the eye facing towards the posterior end of the turtle. The stripes continue on the legs of this turtle. As noticed, the underside of the leg is considerably lighter than the dorsal surface. Their carapace is dark olive-brown. Within each pleural of the shell are yellow-green circular rings. These are then are outlined in black. The hatchlings are similar in colour to the adults, but their colours tend to be more vibrant and contrasting. Lastly, the females are about twice the size of males but the males have longer tails.

Range

This specie can be found below the Fall Line in the Alabama, Tombigbee, Black Warrior, Coosa, Tallapoosa and Cahaba rivers of Alabama and northeastern Mississippi.

Habitat

Their habitat includes sand and clay-bottomed streams with moderate currents. They also have a lot of basking sites like brush piles, logs and other debris. Their diet is made up of mostly insects. Some have also been seen eating crustaceans like molluscs and small fish. Their mating period starts in May and reaches climax from Mid-June to Mid-July. This ends in early August and it lasts about 72 days. Their clutch size ranges from 3 – 7 eggs and incubation can last close to 63 days.

Variations

Graptemys nigrinoda nigrinoda (Northern Black-knobbed Sawback) Graptemys nigrinoda delticola (Southern Black-hooded Sawback)

Similar species

Graptemys barbouri: Also known as Barbour’s Map Turtle grows to about 90 – 140 mm in total length. They have black-tipped spines on their second, third and fourth vertebral scutes. Graptemys caglei: Also known as Cagle’s Map Turtle. The males grow to about 100 mm while the females grow to about 180 mm in total length. Graptemys oculifera: Also known as Ringed Map Turtle. The males grow to about 100 mm while the females grow to about 220 mm in total length.