What is a Crocodile?
Crocodiles are one of the most charismatic animals. Crocodiles are reptiles, carnivorous predators, and aren’t fussy – they’ll eat whatever is available in their habitat. That’s one of the reasons they haven’t had to adapt and change much over the last 50 million years.
The Difference Between Crocodiles, Alligators, and Gharials
Though sharing many similarities in their appearance (morphology), crocodiles, alligators, and gharials belong to different families. However, caimans belong to the same family as alligators.
- Gharials have a very narrow snout.
- Alligators have a U-shaped snout and a pronounced overbite.
- Crocodiles have a V-shaped snout and a longer head. They don’t have an overbite, but they have a sizeable fourth tooth that can be seen even when their mouth is shut; this is a reliable characteristic for identification.
All of these semiaquatic reptiles belong to a vast order called Crocodilia. During the Eocene, crocodiles separated from other crocodilians around 55 million years ago.
What Is An Order?
Scientists organize life into categories to determine how living organisms are related. This system or organization is called taxonomy. It’s like a family tree. From the largest group to an individual animal, these categories are Kingdom, Phylum, Class, Order, Family, Genus, and Species. Crorodilia is one example of an order; primates are another example.
Did you know? The closest living relatives of crocodilians are birds! That’s right, birds and crocodilians evolved from members of a group called archosaurs: dinosaurs.
What Do Crocodiles Look Like?
Crocodiles are predatory reptiles that have adapted to a semiaquatic lifestyle.
Crocodiles are reptiles, which means they lay eggs.
Essential Physical Characteristics
- They can tuck their feet into the sides of their streamlined bodies while they swim to reduce water resistance and build speed. As a result, they propel themselves through the water at speeds of up to 18 mph! It helps them to catch prey quickly.
- Webbed feet help them to make quick turns while swimming or pad along the floor of the shallows.
- They have a palatal flap – firm tissue at the back of their mouth; this stops water from entering their throat. Their nostrils close underwater, too.
- Crocodiles have smooth skin on their sides and bellies (to aid with swimming), while the top of their bodies and tails are covered in osteoderm. Osteoderms are tough scales rich in calcium. As a result, crocodiles are very rugged and act as armor. This armor is multi-purpose: osteoderms are highly sensitive to movement in the surrounding water.
- Eighty teeth line the jaws of a crocodile. Teeth are essential to a crocodile’s survival – losing teeth spells disaster. That’s why they can replace their teeth up to 50 times during their life spans. That’s over 4,000 teeth in a lifetime.
- Smaller crocodiles have a life span of around 35 years, while more enormous crocodiles, like saltwater crocodiles, can live well over 70. In captivity, a male saltwater crocodile at the Australia Zoo, looked after by Steve Irwin, once lived between 120 – 140 years old!
- Crocodiles have incredible senses. They can hear well; they’re nocturnal hunters with fantastic night vision; they have a very well-developed sense of smell to make it easier to hunt on land, and they can sense movements around them through the scales all over their bodies.
Is a Crocodile a Reptile?
In short, yes, a crocodile is a reptile. Crocodiles are semiaquatic reptiles, meaning they live in and out of water. Crocodiles can be found throughout the tropics in Africa, Asia, the Americas, and Australia. Reptiles can be found on every continent in the world, apart from Antarctica.
Reptiles are cold-blooded vertebrates that are closely linked to amphibians. Reptiles evolved from ancestral amphibians around 340 million years ago. When we hear the words ‘cold-blooded,’ we often think of animals being icy cold; however, this is not the case. If an animal is cold-blooded, it cannot maintain a constant body temperature. Therefore, they must seek sunlight to keep their body warm. You will often see crocodiles lying out in the sun for long periods. Being cold-blooded also means that reptiles, like crocodiles, cannot burn as much energy to keep themselves warm. As a result, they end up eating much less food than a mammal of their size or a similar-sized warm-blooded animal.
So a crocodile is a reptile, but they are not alone in this group. Many reptiles generally fit into these main categories: snakes, crocodiles and alligators, turtles, and lizards.
What Do Crocodiles Behave Like?
When we think of a crocodile, we tend to picture a large, dinosaur-like aggressive creature, which is not far from the truth. However, the very design of crocodiles means that they are built to hunt and survive; this is why crocodiles can live to over a hundred years old!
One of the essential features of crocodiles’ behavior is that they are primarily nocturnal animals. Crocodiles are predators, so they spend most of their time in the water, hunting for prey. Crocodiles can also travel several miles over land because they are only semiaquatic.
So, we know that crocodiles like to hunt, but what do they eat? During the initial stages of a crocodile’s life, it consumes insects, crustaceans, snails, small fishes, frogs, and tadpoles. When they get older, crocodiles move on to eat primarily fish. As crocodiles get older, they also develop a better ability to hunt and so can prey upon waterfowl (birds) and mammals. From time to time, one of the more enormous crocodiles will eat a human; however, this is not common.
Hunting, as discussed, is a massive part of a crocodile’s life, and they are extremely good at it. Crocodiles have massive jaws that capture their prey with a slick sideways movement of their mouths. These creatures also have sensitive pressure receptors situated in pits in the scales around their mouths that they use to detect motion. These receptors are essential for helping crocodiles capture prey in the dark, murky waters they hunt in.
So, that’s how crocodiles hunt in the water, but how do they hunt on land? To hunt effectively on land, crocodiles use the element of surprise. First, crocodiles wait for their prey, typically floating or lying motionlessly in the shallow waters where their prey habitually drink. Then, the crocodiles will pounce on them, using their full force of strength, capturing their prey and drowning it in the water. You may have also seen videos of crocodiles spinning their prey in the water. It is a technique that crocodiles use when dealing with larger prey. In this case, the crocodile grips the prey in its jaw and then spins it around in the water rapidly to make it easier to consume.
Another feature of crocodile behavior is their thermoregulation. Crocodiles thermoregulate, which means they perform certain activities to maintain and control their body temperature. They do this by alternately lying out in the sun and cooling off in shaded areas or cooler water. The preferred range of body temperatures for crocodiles is 30–32 °C. Staying within this range for extended periods allows crocodiles a more efficient metabolism. Being able to thermoregulate is essential for crocodiles, so they will fight hard to access both sunny and cool areas. It has been observed that the distinct hierarchies within populations of wild crocodiles mean that the more dominant animals have access to the best sunning spots. These prevalent crocodiles also have access to the best nesting sites to lay their eggs safely and securely.
How Many Species of Crocodiles Are There?
There are 16 different species of crocodiles alive today. They all have unique differences.
For instance, dwarf crocodiles may only grow to one and a half to two meters in length; meanwhile, the saltwater crocodile grows to a vast seven meters long and can weigh 1,000 kg.
Saltwater Crocodile
Five facts about the most enormous reptile in the world:
- The saltwater crocodile is the largest living reptile. Males can grow up to 6 meters long, while females are half the size.
- They have very wide, long snouts and mouths filled with(on average) 66 teeth up to 13 cm long.
- Their powerful jaws make the most vital bite force in the world.
- As with all crocodiles, all saltwater crocodiles lay eggs. Warm nests produce a clutch of primarily male saltwater crocodiles, while a more comfortable nest has mostly female offspring. Females will care for their young for many months, protecting them from harm while they are small and vulnerable.
- Saltwater crocodiles can remain submerged for over an hour and swim at speeds of up to 15 mph – ensuring their success as stealthy ambush predators.
Saltwater Crocodile Habitat:
This crocodile species prefers inland lakes, mangrove swamps, and marshes between the Indian Ocean, Pacific Ocean, and the Coral Sea. Thanks to a special gland under their tongue, they can survive in total salt water (an ability that gives them their name), but they thrive in muddy, brackish waters near the coast.
It means you can find saltwater crocodiles in India, Myanmar, Indonesia’s islands, and Australia’s north coast.
Their numbers had increased by hundreds of thousands since the 1970s when they faced extinction in Australia due to the crocodile skin trade. Both saltwater and freshwater crocodiles live in northern Australia today.
Saltwater crocodiles bask and nest in the terrestrial zones around freshwater and marine waters.
Be careful – mother saltwater crocodiles are very protective of the muddy nests in vegetation on the shore. They build these nests to conceal their eggs – they may lay up to 90 eggs at once! When mothers hear a chirping from within their eggs, they will dig them out of the nest, where they will hatch out of their eggs. Then, she’ll take them gently to the water’s edge, where they’ll have their first swim.
Orinoco Crocodile
These crocodiles have a very long snout, almost as thin as gharials, and pale skin that can change color over time.
- They are critically endangered to extinction. They have been hunted for their skin and are threatened by habitat loss.
Orinoco Crocodile Habitat:
There are small Orinoco crocodile populations living in the freshwaters of Venezuela and Columbia. But, as their name suggests, they live primarily along the Orinoco river.
- Watch as Steve Backshall and a team of conservationists try to rescue the eggs of the Orinoco crocodile. This crocodile is endangered, and conservationists hope to increase its population by raising eggs in captivity.
She responds by protecting her nest. Backshall describes crocodiles as instinctive caregivers.
Mugger Crocodile
This crocodile species digs caves and holes in which they lay their nest of up to 30 eggs. They also undertake long-distance treks in Gir, India – digging burrows to protect themselves from arid conditions and heat.
- They are vulnerable to extinction and threatened by habitat destruction.
Mugger Crocodile Habitat:
These crocodiles live around freshwater wetlands in India, Nepal, Pakistan, and Sri Lanka. They have been found along rivers as high up as 420 meters! Unfortunately, their habitats are fragmented, making it hard for populations to mix.
