I have personally observed a female saltwater crocodile spend nearly two hours submerged. So how are crocodilians which include every species of crocodile, alligator, caiman and gharial able to perform this amazing feat?
A handful of physiological adaptations allow crocodilians to remain submerged underwater — including a specialized heart and a unique metabolic system. Crocodilians have a four-chambered heart — just like people! And just like the circulatory system in people, the heart takes in deoxygenated blood from the body, sends it to the lungs to become oxygenated, the blood comes back to the heart, where it will then be pumped to the rest of the body.
Pretty straightforward. After a short period of time underwater, the oxygen in the lungs is gone crocodilians will typically expel air in order to sink, anyways. Crocodilians have a small opening called the Foramen of Panizza between their left and right aorta of the heart. Skipping all the technical jargon — it means that blood does NOT have to unnecessarily flow to the lungs when the crocodilian is underwater.
This same adaptation is interestingly also linked to efficient digestion. They are members of the order Crocodilia, which also includes caimans, gharials and alligators. There are 13 species of crocodiles, so there are many different sizes of crocodile. The smallest crocodile is the dwarf crocodile. It grows to about 5. The largest crocodile is the saltwater crocodile. The largest one ever found was They can weigh up to 2, pounds kg.
Crocodiles are carnivores, which mean they eat only meat. In the wild, they feast on fish, birds, frogs and crustaceans. At the zoo, they eat small animals that have already been killed for them, such as rats, fish or mice.
They also eat live locusts. In the wild, crocodiles will clamp down on their prey with their massive jaws, crush it, and then they will swallow the prey whole. They do not have the capability to chew or break off small pieces of food like other animals. To help with digestion, crocodiles swallow small stones that grind up the food in their stomachs. Thanks to their slow metabolisms, crocodiles can survive for months without food.
During the Mesozoic Era , about million years ago, the Crocodilia order was one of the top animals on the food chain. Today, crocodiles are found in the tropical habitats of Africa, Asia, Australia and the Americas. They normally live near lakes, rivers, wetlands and even some saltwater regions. One of the largest known populations of American crocodiles is found in the Dominican Republic's at a large saltwater lake called Lago Enriquillo, according to National Geographic.
Crocodiles live in tropical climates for a reason. They are cold-blooded and cannot generate their own heat. This gait allows the crocodile to exert more force in each step, thereby increasing its speed and ground clearance. Depending on the surface, a crocodile can reach speeds of 5 to 10 kph using this technique.
Crocodiles often use the higher speed belly crawl to escape potential threats, usually into a body of water. In high walking locomotion, the crocodile positions its legs erect beneath its body and lifts its entire body and nearly half its tail off the ground. It can travel at speeds of between kph in this way, with short bursts of up to 5kph. The crocodile can do this because it can rotate its feet 90 degrees forward rather than facing out sideways, and holding its legs upright and close to its body when it adopts this gait.
A galloping crocodile is a terrifying sight indeed. This lumbering beast can propel its body at speeds of up to 18kph. It does this by lifting the front of its body up and throwing its front limbs out and forward as the hind limbs thrust the body forward.
It then lands on its front limps first and repeats the process. A crocodile can maintain this speed for a distance of no more than meters before it becomes exhausted. When swimming, the crocodile places its limbs against its body and propels itself by swinging its sinuous, laterally flattened tail from side to side in a wavelike motion. At slow speeds, only the tail moves, and its limbs are used to steer and stabilise it through the water.
But as its speed increases, the crocodile folds its limbs against its body and undulates its body too from side to side, magnifying the trust force its exerts on the water. It steers by using its head as a rudder. By varying the volume of air in its lungs, the crocodile can control its buoyancy.
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