Sea Turtle Anatomy
Class: Reptilia
Order: Testudines
Family: Cheloniidae (all sea turtles with scutes covering their shells) and Dermochelyidae (scute-less turtles, really only referring to the leatherback turtle).
Marine, air-breathing reptiles…
Sea turtles are oxygen-breathing animals. They surface to take breaths regularly, though in a resting state, they can hold their breath for several hours.
Dorsal Anatomy of a Sea Turtle
(Top Shell or Carapace)
Witherington, B. E., & Witherington, D. (2024). Our sea turtles: A practical guide for the Atlantic and Gulf, from Canada to Mexico. Pineapple Press.
Color Key
Blue: Marginal Scutes
Yellow: Nuchal Scutes
Pink: Costal (lateral or pleural) Scutes
Green: Vertebral (Central) Scutes
Orange: Pygal (supracaudal or postcentral) Scutes
Fun fact: Though the limbs in the hind part of a sea turtle are often called back or rear flippers, the proper terminology is to refer to them as hind limbs. For a flipper to be considered so, it needs to be responsible for aquatic locomotion, or propulsion. The hind limbs are primarily responsible for stabilizing their movements.
Ventral Anatomy of a Sea Turtle
(Bottom Shell or Plastron)
Witherington, B. E., & Witherington, D. (2024). Our sea turtles: A practical guide for the Atlantic and Gulf, from Canada to Mexico. Pineapple Press.
Color Key
Blue: Marginal Scutes
Dark Blue: Pectoral Scutes
Yellow: Inframarginal Scutes
Brown: Abdominal Scute
Purple: Intergular Scutes
Pink: Femoral Scutes
Red: Gular Scutes
Orange: Interanal Scutes
Salt Glands
Sea turtles ingest salt water while foraging, and have evolved a way to remove the excess from their bodies
They have salt glands located near their eyes that are used to excrete the excess salt
The excretion of salt can appear as tears - this is a continual process that is happening both on land and in water. The reason the tears appear more prominent in nesting turtles, is because they are not being washed away as they would be in the water.
Magnetite Crystals
Evidence of magnetite crystals has been found in the brains of sea turtles
This suggests that these may be a prominent influencer of their ability to navigate back to their natal beach for breeding
It is believed that they use these crystals to orient themselves with the Earth’s magnetic field similar to how salmon and some bird species navigate as well