Ever seen turtles sunning themselves—often in groups on top of a stump in the middle of a marsh—and wondered why they need to warm themselves up like that?
Remember that turtles are reptiles. Like snakes and lizards, their body temperature depends on their surroundings. They are “poikilothermic”—or cold-blooded. The UV rays produced by the sun allow reptiles to absorb vitamin D3, which is essential for metabolizing calcium in order to ensure good bone development and aid digestion.
Under the shell
Painted turtlesare distinguished by their colours, which range from orange-yellow to orange-red along the edges of the shell, on the plastron and on the legs. They have yellow stripes and a yellow spot on either side of the head, behind the eyes. The painted turtle’s body is enclosed in a bony case consisting of the carapace on top and the plastron underneath, connected by a bridge on either side. Openings in the shell allow the head, legs and tail to poke out. The shell is fused to the turtle’s backbone and ribs. Turtles also have a rigid beak and no teeth, like birds.
Surviving our winters
The painted turtle is adapted to the Québec climate. By late summer, as the photoperiod (hours of sunlight) diminishes, it takes its cue to prepare for a long hibernation. After the spring thaw comes the breeding season. The female digs a hole in a good place for her eggs to develop. Although the young hatch in September, they don’t leave the nesting site until the following spring. During their first winter, buried underground, these tiny turtles endure temperatures as low as -10°C, thanks to a unique survival mechanism: they produce a natural antifreeze that prevents their cells from freezing (and breaking) while the water around them does. This phenomenon occurs only in their first year. In order to survive in subsequent years, they must find a spot in the mud at the bottom of a pond or a marsh that will not freeze.
Hibernating at the Biodôme
Here at the Montréal Biodôme, our four painted turtles experience artificial hibernation. We prepare them by removing them from their habitat and placing them in an isolation room. We give them a veterinary exam, during which we record their weight, check their body mass and look at the condition of their shell. In the following two-and-a-half months, the animal keepers make sure they put on a bit of weight ahead of their two-month hibernation (January and February). The turtles are then placed in a container of water in a large refrigerator, where the temperature hovers around the 4°C mark. The hibernation cycle is crucial to their health and wellbeing.
Spring at last!
Once out of hibernation, the turtles are given another once-over by veterinary staff. They will have lost a bit of weight due to fulfilling their minimal metabolic needs while asleep. The keepers then prepare the turtles for the next step: returning to the marsh in the Laurentian Maple Forest ecosystem in mid-May. If you have a keen eye, you should see them during your visit—perhaps sunbathing!