Why Turtles Bask
Aquatic turtles bask for multiple reasons. After riding out the winter months hibernating in the muddy, silty bottom of their aquatic habitats, turtles need to raise their body temperatures by soaking up some sun when spring arrives. Turtles are ectotherms, which means that their body temperature isn't internally regulated. Instead, they move to warm environments when cold and retreat to cooler environments when overheated.
"Springtime activities like feeding and egg development require higher body temperatures," Jack explains. "When a turtle emerges from the cold water, it fully extends its head and legs to capture the sun's heat. The webbed hind feet are stretched out like solar panels to capture a maximum amount of sun. Blood vessels under the skin dilate and their heart rate increases to quickly deliver warmed blood to the body core to rapidly raise body temperatures."
He adds, "The sun also dries out their skin and shell and helps to eliminate excessive algal growth or external parasites, like leeches. And turtles use ultraviolet rays from sunlight to make vitamin D, which is needed to metabolize calcium from their food to add to their bones and shell."
Prime Turtle Time
The platform has been well-received by turtles as well as passersby.
"I walk by the canal nearly every day and had seen the turtles basking on the trash booms before," says the Aquarium's Director of Field Conservation Charmaine Dahlenburg. "They've really taken to the new island. I've seen lots of turtles, along with groups of people stopping to look at them."
If you'd like to check out the basking turtles for yourself, Jack recommends any sunny spring day when temperatures are warm but not too hot.
"The water is cold, and these turtles haven't eaten since fall, so you will see them out in greater numbers and for long periods of time when it's sunny and warm," he says. "Once the water warms up and days get hotter, the turtles will bask less frequently and for shorter periods."
Maryland is home to 18 native species and subspecies of turtles, as well as three introduced species that have become naturalized. Several aquatic species can be found in the Inner Harbor, including natives such as Eastern painted, red-bellied cooters and snapping turtles, and non-native red-eared sliders. On rare occasions, eagle-eyed observers can spot Maryland's state reptile, the diamondback terrapin, in the harbor.
The Aquarium's involvement in this project aligns with our work on our waterfront campus, where we're constructing habitats to help re-create the many natural Chesapeake Bay microhabitats that were once plentiful in the heart of Baltimore City.