On a dark, cool, and drizzly September afternoon, the first day that felt like Fall, we decided to take one last swim in the lake. (Actually, it was my husband’s idea and I—somewhat bravely, I think—agreed to tag along.) Gone from the T-Dock were the spirited summer crowds, replaced by solitary fishers and a bundled-up couple who seemed alarmed when we began undressing. Gone, too, were the turtles from the log at the marina’s perimeter. The log, our usual swimming destination, is populated in the summer by a phalanx of 6 to 10 turtles basking in the summer sun. Where, I wondered, did they go?
While the study of turtles is called cheloniology, what follows here is a google of facts I collected to satisfy my curiosity. Turtles are reptiles, cold-blooded creatures (ectotherms) whose internal temperature varies according to the outside environment. They breathe air and lay eggs and are omnivores, feasting on fish, worms, insects, and aquatic plants. Their existence on Earth pre-dates snakes and crocodiles.
The turtles we see in Leschi and at Seward Park are either the native painted turtle (distinguished by a black top shell and red or yellow stripes on the neck and legs) or the non-native red-eared slider, which boasts a red or yellow blotch behind its eyes.
And what do they do in the winter when the sun no longer warms them? They bromate. Like many of us endotherms, they get slow and sluggish, but unlike us, they can’t warm up by eating, moving, or layering-on down jackets. So, they submerge themselves in the lake’s bottom or along its banks and as the outside temperature drops, their body temperature drops as well so that their energy needs decrease dramatically.
Mary Hopson on Turtlepuddle.org sums it up: “Most water turtles go deep into the pond and snuggle down into some mud and leaves at the bottom. Then they let themselves get cold. Their bodies slow down, so they don’t need to eat anymore. Their hearts slow down too so that they beat only once every few minutes. They stop breathing through their lungs. Because their bodies are running at such a slow speed, they don’t need much oxygen, but they do need some. They can get the small amount of oxygen they need from the water. It sinks in through some specialized skin cells that are just inside the tail opening...They “breathe” through their tails!”
Turtles are also remarkable for their ability to convert stored glycogen to energy and balance the resulting lactic acid build up with minerals including calcium pulled from their shells. In Canada (so perhaps here?) they return to the same places every winter to bromate and do so in groups.
Dogs and raccoons are the chief predators of our hard-shelled denizens which are at their most vulnerable when they slowly begin moving around again in spring. Another reason to keep your dogs on a leash when appreciating the Leschi shoreline. So, to answer my original question—these incredible creatures are not gone at all. Let’s protect and respect them.