Yesterday was quite warm and several turtles took advantage of the conditions to do a little basking. Why do they bask? In part to get rid of pesky little critters like leeches.
We have at least six different species of aquatic leeches in the millpond. I have seen them attached to turtles, frogs, submerged logs, and the occasional canoe.
This one was not actively feeding, it was just hitching a ride on the turtle's carapace. In its contracted state it was a tad wider than my thumb and about an inch and a half long. Bet it would have been impressive all stretched out.