I found this juvenile male Western painted turtle (Chrysemys picta) today. He was full of energy after eating the sardine bait in the hoop trap. You might be wondering how you determine the sex of these colorful creatures. There are three ways to distinguish the sex of a turtle: 1) length of front nails; 2) body size; and 3) vent position on tail.
Males typically have longer front nails and smaller body weights and carapace lengths. In case you were wondering, carapace isn’t referring to his codpiece, but his shell, so I’m not trying to demean their manhood! Longer nails are used chiefly for courtship and mating. It’s ironic that this trait would be a sign of femininity or poor hygiene with human males, altogether unattractive to the fairer sex! Conversely, females have shorter nails with larger bodies to allow more room for a clutch of 1- 25 eggs. The best way to determine the sex at any life stage (hatchling, juvenile or adult) is to check the position of the vent on the tail in relation to the shell edge. When you flip the turtle over and pull the tail back, don’t be surprised if he/she dumps a present on you after all this excitement! If the vent opening (also known as the cloaca in anatomical jargon) is within or at the marginal of the shell, it’s a female, if it is past the outer edge, it’s a male.
Once the turtle has been sexed, measured and weighed, we file a unique notch on the marginals of his/her shell so he/she can be identified again in future surveys. This does not hurt the turtle and is analogous in humans to filing down finger or toe nails. It’s always wonderful when you release them back into the lake and see a blur of tie-dyed reds, yellows and greens swimming aerodynamically underwater, painting a world within a world for you to discover and explore.