Crocodiles cannot breathe underwater. As reptiles, crocodiles need to breathe with their lungs—they are not like fish with gills. They also cannot breathe through their skin or scale as they are not amphibians.
However, crocodiles can stay underwater for a long time. While there really is no accepted consensus as to how long they can stay underwater, the generally accepted number is eight hours, but only if the water is cold.
How Long can a Crocodile Hold Its Breath?
The average time a crocodile can hold its breath is only 15 minutes, however, if they are not stressed, they can stay underwater for two hours. Many crocodiles will stay submerged for a long time to avoid predators.
They can stay under cold water for eight hours because they do not consume a lot of energy. In warm water, their bodies burn more fuel, so they also consume more oxygen.
In saltwater, crocodiles tongues help them get rid of excess salt from their bodies.
Under extreme cases where a crocodile is under stress, crocodiles can do extended dives. There are records of crocodylians that survived underwater for eight hours, and the water was near-freezing at that point.
What this observation indicates is that temperature is also an important aspect of the crocodile’s physiology. If the water is cold, the crocodile has a lower metabolic oxygen consumption rate. As such, the colder the water, the longer the crocodile could last in it.
Related Article: Do Alligators and Crocodiles Have Gills or Lungs?
Can a Crocodile Drown?
A crocodile can drown, just like any other air-breathing animal. While many scientists quote that crocodiles can last up to two hours underwater, it is not something that crocodiles do under normal circumstances.
Normally, a voluntary drive can only last up to 15 minutes. The usual dive time, based on studies, is only between four and six minutes.
There are studies where scientists held crocodiles underwater to see the maximum amount of time they could stay submerged before dying, and this is probably where many people got the two-hour time frame. However, this is not a crocodile’s natural behavior.
Also, many studies about how long crocodiles can last underwater involved resting crocodiles. In real life, these animals can get stressed and be more active. As such, they will use up more oxygen and need to go back to the surface faster than what scientists have observed.
In truth, a struggling crocodile can drown in less than 30 minutes. Many people who attempted to capture crocodiles can attest to this—the crocs drowned because they could not go back to the surface. Smaller crocodiles will also drown faster than adult ones.
Do Crocodiles Have Gills?
Crocodiles do not have gills. Like humans and many other animals, they have lungs and need to breathe air to stay alive. Crocodiles’ respiratory systems are more similar to birds than mammals.
Birds and crocodiles breathe in a unidirectional manner. Humans and many animals, however, breathe in what is called a bidirectional way.
Read More: Are Crocodiles Considered Amphibians?
In bidirectional breathing, the respiration is two-way. The movement of air requires inspiration and expiration or inhaling and expiration. Humans breathe this way.
Once air comes in, it goes to the lungs, in the bronchi, then finally to the alveoli. It is in the alveoli where the gas exchange happens. The blood that flows in the alveoli deposits carbon dioxide and then takes the oxygen from the air. Finally, the air is exhaled.
Crocodiles do not breathe like this. They breathe in a loop, like birds. The difference between crocodiles and birds is that birds have air sacs, but crocodiles don’t.
Do Crocodiles Breathe Through Their Skin?
Crocodiles do not breathe through their skin because they are reptiles, not amphibians. Amphibians are the only animals that can breathe through their skin.
Amphibians like frogs also have glands that secrete mucus to the skin, keeping it wet. If an amphibian’s skin gets too dry, it cannot absorb oxygen from the water, and it will die. Crocodiles do not need water to breathe.
How Do Crocodiles Breathe?
Crocodiles breathe like birds. The process is called unidirectional breathing, which means they can breathe in and exhale at the same time, in a continuous loop. This helps them conserve energy and minimize their movements in the water.
What it means is that they can inhale and exhale at the same time. As such, they do not consume a lot of energy to swap gases (carbon dioxide and oxygen). Since they can breathe continuously, they can also get a lot of air consistently.
Read Also: Do Crocodiles Lay Eggs?
Do Crocodiles Breathe Through Their Mouths?
Crocodiles can breathe through their mouths when on land, but when crocodiles are in the water they close their mouths and breathe through their nostrils, which remain above the surface.
The crocodile has a valve in its throat, called the palatal valve. On land, crocodiles open this palatal valve so they can get more air. When crocodiles bask under the sun, they tend to breathe more through their mouths than their noses.
In water, they close this valve and breathe through their noses, but only if the snout is on the surface.
Crocodiles do not open the valve underwater, as it can lead to drinking the water and, eventually, drowning. Even if they are holding their prey with their teeth, the valve remains close.
Do Crocodiles Sleep Underwater?
Crocodiles can not sleep underwater because they can not breathe underwater. During freezing conditions, some crocodiles can enter a semi-dormant state called brumation where they keep 90% of their bodies underwater, but leave their snouts poking up through the ice to breathe.
Crocodiles sleep on land, and when they do, they sleep with half their brains awake. It is why they also have one of their eyes open. They have evolved to do this to protect themselves. If a person approaches a sleeping crocodile, it will know and defend itself.
Crocodiles do not breathe underwater; they do not have the means to do this. They breathe through their mouth and lungs, and they need to be in the air to do it. Crocodiles are not amphibians, and they cannot breathe through their skin.
They can stay underwater for 15 minutes, but the longest recorded under a stressful condition is eight hours. However, the average duration by which they stay submerged in a voluntary dive is only between four and six minutes.
Stuart is the editor of Fauna Facts. He edits our writers’ work as well as contributing his own content. Stuart is passionate about sustainable farming and animal welfare and has written extensively on cows and geese for the site.