This is Nicky. She is a kind of water turtle called a river cooter. She has been my pet for 29 years. In the picture, she is sitting in the sun to warm herself.
Temperature is important to turtles.
Turtles are ectothermic animals. They need to be warm to move around and eat. If they get too cold, everything in the body will slow down. Then they can't eat and digest food. The heart slows down and the lungs do too.