Fascinating facts on Sea Turtle Biology

Let’s explore a little about the biology of this amazing species. Their size, shape, ecology and other factors make sea turtles unique and amazing.

The biology of sea turtles tells us a lot about dinosaurs. It is a way to get to know them. They, like dinosaurs, are large in size and migrate very long distances. They also share with these large reptiles the lack of metabolic processes to generate heat, unlike mammals and birds.

The Shell

Let’s start by getting to know its shell. In all species of turtles, except the leatherback, the carapace is formed by shields, made up of plates of dermal origin. It is composed of a protein very similar to the one that makes up our nails and hair (keratin). The shell covers the bones of turtles and is formed as soon as the turtle is in the egg stage. The carapace of leatherback turtles does not have keratin scutes, but is covered by a leathery skin over a loose mixture of thin bony plates connected by soft cartilage, giving it the appearance of “leather”.

The Plastron

The plastron is the ventral part or underside of sea turtles. It is connected to the shell by lateral bridges, which are hard shell plates. It also develops in the embryonic phase of the species, i.e. while in the egg. It is composed of a series of plastron bones that resemble the chest in humans.

Both the carapace and the plastron have functions of protection against predators, protection of vital organs and temperature regulation.

The Skeleton and the Brain

The skeleton of sea turtles is like that of few other creatures on earth; they have an internal skeleton and an external skeleton (the carapace and plastron). The internal skeleton is composed of thick bones and helps them maintain their shape; the muscles of the internal skeleton are fused to the external skeleton.

Their brain is relatively smaller than their large body; however, it has a great adaptation that allows them to live and continue to function in environments with very little oxygen for long periods of time and also research conducted by scientists from several Mexican universities, showed that they have a neural system that allows them to perceive the earth’s magnetic field, which allows them to know their geographical location in the ocean and on land.

Jaws and Beaks

Instead of teeth, sea turtles have horny beaks covering their upper and lower jaws, made of the same protein as the shell (keratin). The shape of their beaks varies among species and is specialized for the type of diet of each species. For example, in the green turtle, the beak is serrated like a knife to cut seagrass, while in the hawksbill turtle it is pointed like a hawk’s to remove pieces of sponge from corals. Beaks can be used for species identification


The flippers are perfectly adapted for the aquatic environment, although they also work wonders when digging their nests on the beach. The front flippers serve to propel them, and the hind flippers, more like a rudder, to steer their way. Many species have one or two claws on each front fin that are easily visible.

Desalination System

Sea turtles have a very specialized system for desalinating water. Their esophagus, which connects the mouth to the stomach, is adapted to eliminate the salt they take in from seawater and their diet. In addition, they have a gland that helps them excrete salt that their kidneys cannot process. This gland is close to their eyes, which has inspired the myth that “turtles cry” because apparently they do.

Diving Capacity

To conclude this tour through the biology and anatomy of sea turtles, we must highlight their fabulous diving capacity. In fact, they are much more similar in this respect to marine mammals than to other reptiles. They spend most of their time submerged, leading a fairly active underwater life, searching for food, sleeping or even hibernating in the mud, as happens in winter in some places in the Florida Keys or the Gulf of California in Mexico. The leatherback turtle earns the award of the best diver, as it has been reported that it can dive up to 900 meters.

We invite you to continue exploring the world of these fascinating creatures, we know that through knowledge we will make progress and raise awareness to conserve our sea turtles.

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