Crocodiles use the water, sun and shade to maintain their preferred body temperature of 30–33 °C. When basking, they orientate their bodies to ensure the maximum surface area is exposed to the sun. Crocodiles are unable to sweat. To avoid over-heating they may return to the water or lie with their jaws agape, allowing cool air to circulate over the skin in their mouths. This process of heating and cooling their bodies is called thermoregulation and is crucial for many bodily functions including digestion and locomotion, and ultimately for their survival.
Often observed basking on the banks of watercourses where they are generally inactive, crocodiles are less likely to be seen when they are in the water. Although livelier in the water, crocodiles are able to swim just below the surface, with only their eyes and nostrils visible.
Crocodiles are one of the few reptiles to have a four-chambered heart (like mammals). They can also stay underwater for extended periods of time because they have the ability to slow their heart rate, allowing them to hold their breath.
A unique feature of crocodiles is their inability to maintain strenuous activity for extended periods of time. They can easily become exhausted while capturing prey or fighting other crocodiles. Extreme exertion is carried out anaerobically (without oxygen) and must be followed by a period of rest so that the "oxygen debt" can be repaid to their muscles. The result of anaerobic activity is a build-up of lactic acid in the blood. Although crocodiles can withstand higher levels of blood acidity than other animals, sometimes it can be fatal.
By this,you have never thrust a crocodile smile.A crocodile has a constant supply of new teeth. Each time an old tooth falls out a new one will replace it.Crocodiles have growing spurts during the hot wet months. This creates distinct growth rings in the crocodiles' bones that can be used to estimate their ages. Based on an analysis of growth rings, one adult male freshwater crocodile was estimated to be about 70 years old, so it is possible that they could reach 100 years of age.
Estuarine crocodiles are unique in the reptile world in that they use their blood system to remove salt from their body. Salt glands embedded in their tongue tissue excrete excess salt when the animal is living in a highly saline environment.Crocodiles use physical displays, chemical and vocal signals to communicate. They have no vocal chords so forcing air from their lungs through the back of the throat or nostrils is how they make their vocal noises.
Crocodiles are large and skilful predators that hunt by stealth. Their muscular tail propels them through the water and allows them to lunge forward with great power and speed. It can also be used to thrust them vertically to capture a bat or bird in mid-flight or in foliage.
Crocodiles are able to see underwater due to a transparent lid that closes over their eye for protection. They also have excellent night vision, thanks to a specialised retina, as well as a keen sense of smell. Small sensory buds around the top and bottom jaws allow crocodiles to detect vibrations - crucial when hunting in murky water.
Crocodiles are opportunistic feeders that feed on a variety of animals. Their jaws have immense crushing power, enabling them to easily break through skulls and other bones. Prey is not chewed but swallowed as large chunks. If the items are too big to swallow whole, the crocodile may roll several times or shake its head in an attempt to break off a more manageable piece. Although their stomach secretions are highly acidic, they cannot digest some items, such as fur, hooves and turtle shells. These items collect in the stomach and may either be passed through undigested or turned into "hairballs" and regurgitated later.
Studies have shown that crocodiles are able to convert as much as 50–70 percent of their food into growth and energy. By contrast, humans use only 3–4 percent. Up to 80 percent of our food is used to produce heat and maintain a constant body temperature. This efficiency in crocodiles means that they can go for months without eating.
The future of the crocodile is very poor.So that nowadays crocodiles are being protect by WWF.Australia is one of the very few places in the world where estuarine crocodiles have a good chance of survival in the wild, and the only country where the freshwater crocodile is found. Because crocodiles are an important part of the food chain and help keep our wetland environments healthy and stable, protecting them is vitally important. This means Australians have a responsibility to conserve and manage the country's crocodile populations carefully.
When visiting crocodile habitats, take care. Respect these animals and appreciate that, like other native animals, crocodiles are part of the natural and cultural heritage of northern Australia.
Follow these simple guidelines to help protect crocodiles:
- never interfere with crocodiles or their eggs;
- report any incidents of crocodile killing or poaching to the nearest EHP office
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