Planner graph on Kemp Ridley and Olive Ridley turtles' carapace

Kemp's Ridley or Lepidochelys kempii is the smallest of all sea turtle species. Reaching maturity at 2–3 feet (61–91 cm) long and averaging only 45 kilogram. It's carapace contains five vertebral scutes running down the midline, while five pairs of costal scutes border them. The resulting planar graph due to this scalation is 3-regular 28 vertices and 42 edges. Exactly same as as that of Loggerhead or Caretta Caretta.



Olive Ridley or Lepidochelys olivacea is also one of the smallest turtle species. its heart-shaped carapace is characterized by four pairs of pore-bearing inframarginal scutes on the bridge, two pairs of prefrontals, and up to nine lateral scutes per side. Scalation can be asymmetrical i.e. 6 lateral scutes on one side and 8 on the other.

Planner graph on Loggerhead Turtle's carapace

The Loggerhead sea turtle or Caretta Caretta is the world's largest hard-shelled turtle. It's carapace contains five vertebral scutes running down the midline, while five pairs of costal scutes border them. The resulting planar graph due to this scalation is 3-regular 28 vertices and 42 edges.

Planner graph on Green Turtle's carapace

In graph theory, a planar graph is a graph that can be embedded in the plane, i.e., it can be drawn on the plane in such a way that its edges intersect only at their endpoints.

A graph is said to k-regular if all the vertices of the graph has dgree k.



The Green sea turtle or Chelonia mydas has a dorsoventrally flattened body. Its carapace is composed of five central scutes flanked by four pairs of lateral scutes. The resulting planner graph is 3-regular with 24 vertices and 36 edges.

Graph on sea turtle carapace

Sea turtles belong to the superfamily Chelonioidea and inhabit all of the world's oceans except the Arctic. There are seven species of sea turtles.

Family Cheloniida

Chelonia mydas or green turtle
Eretmochelys imbricata or hawksbill turtle
Natator depressus or flatback Turtle
Caretta caretta or Loggerhead Sea Turtle
Lepidochelys kempii or Kemp's Ridley turtle
Lepidochelys olivacea or Olive Ridley turtle

Family Dermochelyidae

Dermochelys coriacea or leatherback turtle



The above Image shows how to identify species of a sea turtle based on its carapace or the back. Anyone with idea of Graph theory would immediately recognize the graphs drawn on the carapace of different turtle species. I believe this is a good criterion for automated species identification from sea turtle photographs.