Everyone knows that most mammals breathe through the mouth and nose. Meanwhile, frogs can breathe through their skin. But what about turtles? How do these hard-shelled creatures get their oxygen?
You may have heard a strange rumor that turtles can breathe through their bottoms. But is this true?
Technically, turtles do not breathe through their selves. That’s because turtles don’t have “breeches”; Instead, they have a multipurpose opening known as the cloaca, which is used for sexual reproduction and egg laying as well as for expelling waste. However, they do participate in a process called cloacal respiration, which, in a less technical sense, can be interpreted as “butt breathing.”
During spotted respiration, turtles pump water through their patchy orifices and into two sac-like organs known as the bursa, which work somewhat like aquariums lungsCraig Franklin, a wildlife physiologist at the University of Queensland in Australia who has extensively studied conical breathing, told Live Science. The oxygen in the water then diffuses through the papillae, which are small structures that line the walls of the bursa, and into the turtle’s bloodstream.
Related: Why do turtles live so long?
However, closed breathing is very inefficient compared to normal aerobic respiration, and all turtles have the ability to breathe air with their lungs more easily. As a result, spotted breathing is only seen in a few freshwater species that rely on this unconventional method to overcome challenges in unique environments where air is difficult to breathe, such as fast-flowing rivers or frozen ponds.
clokal heroes
River turtles are the main group of turtles that have really mastered the cloacal breathing. Globally, there are about a dozen river turtles that can properly utilize cloacal breathing, about half of which live in rivers in Australia; These include the River Mary turtle (Elusor macrurus) and the white-throated turtle (Elseya Albagula), Franklin said.
However, some species of river turtles are much better than others at clump breathing. The undisputed hero is the Fitzroy River Tortoise (Ryudette Lokobes) from Australia, which can derive 100% of its energy through cloacal breathing. “This allows them to stay underwater indefinitely,” Franklin said.
But for all other species, spotted breathing only prolongs the amount of time they can stay underwater until they have to surface again for air. For example, instead of diving underwater for 15 minutes [while holding their breath]They can stay underwater for several hours.”
The ability to stay underwater for long periods of time is very beneficial for river turtles because going to the surface can be hard work. “For a turtle that lives in fast-flowing water, going to the surface to breathe is somewhat of a problem because you can get carried away,” Franklin said. He added that staying near the riverbed also made it easier to avoid predators such as crocodiles.
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Avoiding predators is especially important for small turtles, which can be targeted by birds and larger fish. “The greatest predation risk for a hatchling turtle is swimming through the water column to the surface,” Franklin said. As a result, juveniles are usually much better at closed breathing than adults, allowing them to spend more time near the river bed until they are old enough to begin venturing more frequently to the surface. Therefore, it is possible that additional river turtle species are also capable of thoracic breathing like juveniles but lose this ability later in life, Franklin said.
However, spotted respiration is much less efficient than aerobic respiration because pumping water into the pouch requires a lot of energy, reducing the net energy gain the turtles receive. “When we breathe air, there is virtually no need for energy” because gases It’s light and flows freely in and out of our lungs, Franklin said. “But imagine trying to sniff a sticky liquid back and forth.” He added that water also contains about 200 times less oxygen than an equal volume of air, so turtles have to pump out more of it to get the same amount of oxygen.
Related: How do animals breathe under water?
There is also another cost to cyanotic breathing. When oxygen diffuses through leather From the follicle and into the bloodstream, sodium and chloride ions (charged particles) within the papillae, which are vital for the functioning of cells, diffuses in the opposite direction into the water, stopping the cells from working properly. To counter this, turtles have developed special pumps that suck lost ions back into cells to maintain normal ion levels. This process, known as osmosis regulation, requires additional energy, further reducing the net energy gain from conical respiration.
stuck under the ice
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There are also about six or seven species of freshwater turtles hibernating across North America that are capable of A more limited form of cloacal breathing. These species, such as the blanding turtle (Emydoidea blandingii), spending months trapped under layers of ice covering puddles during winter. Some of these turtles have been under ice for more than 100 days without being able to breathe even once, Jackie Letzgos, a wildlife ecologist at Laurentian University in Ontario, told Live Science. Alternatively, these turtles can also absorb oxygen through their bursa, as well as by gargling with water in their throats, which is known as buccal infusion, Letzgos said.
However, Franklin said that the spotted breathing that hibernating turtles exhibit is much less complicated than what river turtles are able to do. Instead of actively pumping water into their pouch as their river-dwelling relatives do, hibernating turtles absorb oxygen, which passively diffuses through the skin in the pouch. This process is very similar to cutaneous respiration – when oxygen diffuses through the animal’s skin, which occurs in amphibians, reptiles, and, to a limited extent, some mammals, including Humans.
hibernating turtles escape this passive form of cloacal respiration because they experience significantly reduced breathing. metabolism modifier, which means they require less energy, and therefore less oxygen. While under the ice, these turtles don’t move much, and keep their body temperature It’s close to freezing and can switch to anaerobic respiration — the last resort for power generation without oxygen — when oxygen is low, Letzgus said.
Originally published on Live Science.