Turtle's Anatomy - Shell

Figure 1: Shell of a red-eared slider turtle

The shell which can be seen in Figure 1 consists of bony plates that are mostly covered with shields called scutes (osteodem). The shields are entirely made of keratin. The shell of the turtle is divided into 2 sections:

• Upper or dorsal carapace
• Lower, ventral carapace or plastron

These are similar to scales and they are derived from the red-eared slider’s epidermis. However, the top layers of the scute will fall off when the red-eared slider begins to shed. A bridge connects the carapace and the plastron.

The carapace (top shell) is nicely rounded and smooth. The carapace has a black and yellow pattern. Hatchlings start with a bright green carapace that is slightly soft whereas adult red-eared sliders have a darker green carapace. As the red-eared sliders age, the colour of the carapace will grow darker and the patterns will be less visible. Hence, this is one way to determine the age of the red-eared slider. The carapace of a red-eared slider can be seen in Figure 2.

Figure 2: Carapace, upper section of the shell

The plastron is similar to the carapace. it is also smooth but it is usually yellow in colour with a distinct and unique pattern that can be seen in Figure 3.

Figure 3: Plastron, lower section of the shell

Let’s go in depth on the carapace and the plastron. Both section of the shells have their own specific name at all corners of the shell which can be seen in Figure 4.

Figure 4: Illustrative structure of carapace and plastron scutes respectively

Carapace Scutes

• Vertebral scutes cover the spinal region of the turtle.
• Pleural scutes cover the ribs of the turtle.
• Marginal scutes are located at the outermost scutes of the turtle.
• Supramarginal scutes fall between the marginal and pleural scutes.
• Cervical scutes cover the neck region of the turtle.

Plastron Scutes

• Intergular scutes cover the throat of the turtle and the anal scutes.
• Gular scutes are the first lateral scutes followed by the humeral scutes.
• Pectoral scutes are laterally paired near to the pectoral girdle of the turtle.
• Abdominal scutes cover the abdomen of the turtle.
• Femoral scutes cover the femur of the turtle.

Reference

1. Newman, S. (2016). Red-Eared Slider Turtle Facts, Habitat, Diet, Pet Care, Pictures. [online] Animalspot.net. Available at: http://www.animalspot.net/red-eared-slider-turtle.html [Accessed 23 Apr. 2016].
2. Virginiaherpetologicalsociety.com. (2016). Red-eared Slider. [online] Available at: http://www.virginiaherpetologicalsociety.com/reptiles/turtles/red-eared-slider/red-eared_slider.php [Accessed 23 Apr. 2016].