One of the 41 turtles and tortoises on WAnimals

Reptiles · Testudines · Emydidae

Northern Map Turtle

Graptemys geographica

Least Concern

The species is abundant and widely distributed; it faces no significant short-term risk. See full glossary

The northern map turtle owes its name to the pattern of fine pale lines on its shell, reminiscent of the contour lines of a map. It shows one of the most extreme cases of sexual dimorphism among turtles: the females are far larger than the males and have a disproportionate head, adapted to crushing molluscs.

Weight

500 g – 2.5 kg

Size

10 cm – 27 cm

Lifespan

30 years

Diet

Omnivore

Combines animal and plant food depending on availability.

Activity

Diurnal

Active mainly during the day.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Easy

Fun facts

  • Males and females eat different things: the females, with their huge heads and jaws, crush clams and snails; the males, far smaller and narrow-headed, eat aquatic insects. It is niche separation within a single species.
  • Females can weigh up to ten times as much as males, one of the most extreme cases of sexual dimorphism among the chelonians.
  • They are seen lined up on logs and rocks basking in large groups, and slide into the water all at once at the slightest movement on the bank.

Life cycle & biology

Skeleton type
Vertebrate - internal bony skeleton with a shell (reptile)
Habitat & environment
Large rivers and lakes with current and stony bottoms in eastern North America
Size at birth
About 3 cm of carapace on hatching
Sexual maturity
14 years
Gestation / incubation
70 days of incubation
Litter / clutch size
12 eggs

Sources consulted: https://www.iucnredlist.org/ | https://animaldiversity.org/ | https://es.wikipedia.org/

Best time: From April to September in rivers and lakes of eastern North America, when it basks in groups on floating logs.

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