Within the group of vertebrates we find the order Testudines, which includes all turtles, both aquatic and terrestrial. Without a doubt, they are very peculiar animals, because their shell, regardless of the species, makes them always easily recognizable. On the other hand, they are full of various curiosities, which with the advancement of science have become much better known. One of these data and what else raises doubts is his way of breathing.
In this article on our site we will explain how sea and land turtles breathe, so you will find out if they are able to breathe under the water or not.
How do tortoises breathe?
Land turtles are vertebrates that have pulmonary-type respiration, so it is through these organs that they carry out their breathing process. Now, although tortoises breathe through lungs, their anatomy is very different from other vertebrates, so their breathing process also changes.
The turtle shell is a thoracic cage that has been modified and forms part of its spinal column, where the ribs have also been fused, which has as a consequence that in the process of inspiration and exhalation an expansion of the thorax region does not occur, as is common in other vertebrate animals. This anatomical constitution means that the lungs, in their upper region, are glued to the shell, while the lower part is attached to other organs. This position limits their expansion.
But life in general uses complex processes that offer necessary alternatives so that the species can develop properly, and in this the turtles have not been left out. To overcome the limitation of the expansive movement of the lungs, which allows the mobilization of air, turtles use the abdominal and pectoral muscles as if they were a diaphragm, therefore that make the air enter and leave the lungs thanks to two types of movements: one that pushes the air into the lungs and the other that takes it out, so that gaseous exchange can occur in the animal.
Certain studies [1] suggest that this ventilation mechanism that occurs in turtles was possible through the anatomical evolution of the same, where there was a division of labor carried out by structures such as the ribs and muscles located in the trunk, in which, due to the limitation of their movements, their function was replaced by other muscles, such as the abdominals. As for the widening of the ribs, these became the main means of stabilizing the trunk of the animal. It is estimated that this entire transformation process must have occurred about 50 million years ago, before the evolution of the shell to a fully ossified structure took place.
Respiration of sea turtles
Sea turtles and also those that live in freshwater bodies are still vertebrate animals that, in fact, belong to the same order as land turtles. In this sense, aquatic turtles also breathe through lungs, so they need to come to the surface to take in air
Now then, both marine and freshwater turtles have developed other mechanisms to be able to carry out gaseous exchange underwater and thus be able to take in oxygen. In general, vertebrates, regardless of the type of respiration they have, due to the metabolic demands they have on their bodies, have little tolerance for the absence or deficiency of oxygen, and for a sea turtle, for example, it would be a limitation to have to rise every few minutes to the surface to breathe. Likewise, it would also be limiting for species of freshwater turtles, which develop brumation processes under water, as is the case of the red-eared slider (Trachemys scripta). If you don't know what brumation is, in this article we explain what this process consists of: "What is brumation?".
So how do terrapins breathe? It is common for turtles with aquatic habits, whether in marine or freshwater environments, to have a bimodal type respiration, that is, they dothrough its lungs , but also through the cloaca , which is the final part of the animal's digestive system and connects with the outside, so that it is lined with branched papillae that allow gas exchange. In this sense, cloacal breathing is possible because the animal contracts a series of muscles that allow the pumping of water inside through the hole located in the cloaca. Subsequently, the water reaches structures known as "cloacal bags", which are shaped like bags and have a specialized tissue where gas exchange occurs, that is, it is the place where the turtle can take oxygen from the water to pass it to the blood and transport it to the rest of the body.
Since there are hardly any absolute rules in nature, there are turtles with exceptional behavior in relation to breathing. Thus, for example, the painted turtle (Chrysemys picta) carries out cloacal respiration very efficiently, which allows it to spend long periods of time underwater, even in aquatic bodies with very little or almost no oxygen, as in which freezes the top layer, preventing gas exchange through the lungs.
Do sea turtles have gills?
Gills are organs used by different aquatic life animals to be able to breathe underwater. However, these structures are not part of the turtle's anatomy, therefore, sea turtles do not have gills.
However, there are vertebrates that do have them, apart from fish, such as amphibians in their larval phase, which have similar gill structures that are usually lost in metamorphosis. However, there are cases where they remain in adults, such as the Mexican salamander.
How long can a turtle last underwater?
The time a turtle can last underwater can vary, but thanks to its cloacal respiration, in some cases there are individuals that can last much longer than any other lung-breathing vertebrate can. Thus, for example, the Fitzroy tortoise (Rheodytes leukops) can last from about 10 hours to about three weeks underwater Another example is found in the painted turtle, which can stay underwater for up to more than four months
In general, we can say that a resting turtle can spend between 4 and 7 hours under water. However, when they are on the move or under stress, they need to come to the surface more continuously for air because their metabolic demand increases.
If you love these animals, don't miss this other article with more Curiosities about turtles.
Decompression syndrome in sea turtles
Decompression syndrome is a pathology that originates when an individual submerged at a certain depth ascends rapidly and the atmospheric pressure drops abruptly, causing nitrogen to pass from the lungs into the blood and form bubbles that cause this syndrome and its complications.
Sea turtles, to avoid suffering from this, limit the passage of blood to the lungs, so the nitrogen does not dissolve and they can quickly rise to the surface without any problem. However, if the turtle is stressed, such as when it is trapped in a net, it cannot limit the passage of blood to the lungs, so when it is filled with this liquid, gas exchange occurs and nitrogen produces the formation of bubbles that have fatal consequences for the animal, which can cause death once it is abruptly removed from the water.
In this way, the decompression syndrome in turtles originates mainly due to fishing when trawling nets are used where they are trapped. Unfortunately, there are not a few sea turtles that suffer from this syndrome and end up dying. Fortunately, there are associations and foundations that are responsible for treating them to rehabilitate them and return them back to their habitat, such as the Fundación CRAMThis foundation is dedicated to the rescue, rehabilitation and liberation of marine animals that are injured, a task that is undoubtedly essential for sea turtles that suffer accidents with boats or are trapped in nets. We can help in this work by supporting the foundation through donations, which can be monthly or specific and of the amount that we want. With just €1 a month, we help a lot!
