A Red-eared Slider in a Koi Pond on the campus of Texas Woman’s University in Denton, Texas.
Wikipedia describes Red-eared Sliders as follows:
Turtles also have a complete skeletal system, with partially webbed feet that help them to swim and that can be withdrawn inside the carapace along with the tail. The head can also be completely withdrawn inside the carapace. The red stripe on each side of the head distinguishes the red-eared slider from all other North American species and gives this species its name, as the stripe is located behind the eyes where their ears would be. These stripes lose their color over time. Some individuals can also have a small mark of the same color on the top of their heads. The red-eared slider does not have a visible outer ear or an external auditory canal; instead, they rely on a middle ear entirely covered by a cartilaginous tympanic disc.
The main internal organs of these reptiles are the lungs, heart, stomach, liver, intestines and the urinary bladder, in addition to the cloaca and the tail, which are important external organs. The tail is important as it helps an individual to steer as it is swimming.