Crocodile Saltwater Crocodile

Crocodiles are large carnivorous lizard-like semi-aquatic reptiles and one of nature's deadliest killing machines. They belong to the order of animals called Crocodilia, which also includes alligators, caimans, and gharials. Crocodiles are ambush hunters that lie in wait for their prey to come within range. Then, with a combination of speed, stealth and as tremendous bite force and strength, they will overpower their victim and make a meal of them.

Crocodile Description

Crocodiles have broad bodies with tough scaly skin, short limbs, clawed feet and long muscular tails. They may appear slow and clumsy on land, but they can swim at speeds of up to 32kph (20mph) and run for short distances at speeds of up to 18kph (11mph). Crocodiles inhabit many habitats and ecosystems, including tidal flats, mangroves, estuaries, rivers and lakes.

Crocodile Attacks

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There are two types of crocodiles. The larger and more dangerous of these is the Saltwater Crocodile which can grow to over 6m (20ft) in size and weigh over 1,000kg (2,200lb). The Saltwater Crocodile has a lifespan of about 70 years. The smaller Freshwater Crocodiles inhabit rivers, lagoons, creeks, swamps and watering holes. Freshwater Crocodiles have a lifespan of 50-60 years.

Photo: Crocodile's nose, eyes and ear-slits

A crocodile has a long head and snout. Its eyes, ears, and nostrils are on top of its head to keep them above the waterline. A crocodile's daytime vision is good and can probably see some colour. And because of its vertical pupils, it has excellent night vision. Furthermore, it has transparent eyelids that enable it to see underwater. A crocodile's ears are slits located just behind its eyes (see photo)—these close when the crocodile submerges. Crocodiles have excellent hearing. The crocodile's nostrils, located on top of its snout, allow it to breathe while submerging its body underwater. It has nose flaps that close its nostrils to prevent water from entering its lungs when it submerges. Finally, it has special organs in its snout, giving it an excellent sense of smell.

Photo: Crocodile mouth full of teeth

The crocodile has an elongated snout and mouth with massive jaws containing 40-60 large teeth. These jaws have several strong and pointed "holding teeth" designed for grasping and holding on to its prey. Other teeth are razor-sharp and designed to chew through their victim. When slamming shut, a crocodile's massive jaws can exert a 'bite force' of as much as 2300 kilograms of pressure per square inch. (A human generates only 45). With this force, it can grasp and demolish almost any animal it catches. While the crocodile has extremely powerful muscles to close its jaws, those to open them are very weak. They are so weak, in fact, that a person could literally hold them shut with his bare hands. A crocodile replaces its teeth continuously and may replace as many as 8,000 in its lifetime. The crocodile's tongue, attached to the bottom of its mouth, does not move and has special glands to eliminate excess salt.

The crocodile has legs that protrude outwards from the side of its body. These legs are short with webbed rear feet. On land, it is rather ponderous, sliding along using its legs to propel itself or heaving itself up on its four legs to move. But it can gallop for very short distances at speeds of up to 18 kilometres an hour.

How Crocodiles move

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When on the surface of the water or swimming slowly, the crocodile splays out its front and back legs to act as stabilisers to prevent it from capsizing in the water and also for paddling and steering. When swimming rapidly, the crocodile tucks its legs close to its body.

The crocodile has a long, powerful and streamlined tail. This tail is laterally flattened—that is, the tail is much taller than it is wide. This gives the tail a large surface area to push against the water when the crocodile whips its tail from side to side in an ‘S' shaped pattern to propel itself through the water. It can also use its tail as a weapon to slash and disable its prey or knock it into the water.

A crocodile can swim in short bursts at speeds up to 29 kph (18mph) over short distances. An alligator swims at 32kph (20mph). This is over three times faster than the fastest human swimmers. When swimming, the crocodile usually tucks its legs against its body to streamline its body and reduce drag and uses them like rudders for steering.

Crocodile Swimming

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A crocodile can remain submerged for up to an hour. It does so by reducing its heartbeat to just 3-4 beats per minute, thereby reducing its metabolic rate and oxygen requirements. It does this by closing its nostrils and a large fleshy flap of skin at the back of its throat to prevent water from entering its lungs and stomach when it opens its mouth underwater.

Crocodiles are cold-blooded and cannot regulate their internal body temperature. Instead, they depend on external temperatures to regulate their body temperature. Therefore, they actively move back and forth between warm and cooler parts of their environment to maintain an ideal core temperature between 30-33C. On warmer days, they seek shade to avoid overheating, and in colder weather they will bask in the sun to heat up. Additionally, crocodiles are known to open their mouths wide when resting in the sun; this postural behaviour cools them down using evaporative cooling via the mouth.

Crocodile Habitat Where Do Crocodiles Live?

Photo: Crocodile habitat map

Crocodiles live in warm and temperate climates in freshwater rivers, estuaries, creeks, mangrove swamps, coastal marshes, and lagoons. Crocodiles do not live at elevations higher than 250m above sea level. Being cold-blooded, they move to warmer areas when temperatures are too cold. While crocodiles prefer travelling in water, there are instances where they have travelled overland for distances of 1,600 km (1,000 miles) in search of new territory.

Saltwater crocodiles live in the coastal regions of Southeast Asia and northern Australia. They spend the tropical wet season in freshwater areas such as swamps and rivers. Then, as the weather warms up, they move downstream to estuaries, coastal areas, and even the open ocean.

Crocodiles are territorial and will compete aggressively with others for territory. The most dominant male will usually occupy the prime "waterfront" real estate. Lesser crocodiles will inhabit more marginal areas. Crocodiles hibernate or become dormant in burrows dug in the sides of river banks during colder months or periods of drought.

Crocodile Diet What Do Crocodiles Eat?

Photo: Crocodile catching a flying bird

Crocodiles will eat almost any animal they can catch. These include fish, turtles, crustaceans, insects, frogs, lizards, birds (sometimes snatched out of the air), and other animals, large and small. The size of the prey a crocodile will attack is only limited by the crocodile's size and appetite. They will even attack and eat humans if they can. Crocodiles are also cannibalistic. Dominant males may attack and eat smaller male crocodiles. Juvenile crocodiles start on a diet of insects, small fish and small mammals. As they grow older, they progress to larger and larger prey. It was generally thought that crocodiles were strictly carnivorous. But recent research has found evidence of crocodiles eating fruit such as wild grapes, elderberries and citrus fruit directly from trees.

Photo: Crocodile eating another crocodile

The crocodile is an opportunistic ambush predator that prefers to hunt at night. But it will not let a good daytime opportunity go by and will also catch prey during the day if they come its way. The crocodile will cruise or stay motionless in its water habitat until an unwitting animal comes within striking range. It will then move silently into position and launch itself with tremendous speed and power out of the water to grasp its prey in its powerful tooth-filled mouth.

A crocodile's eating habits are best described as a ‘chomp and gulp' approach. While it has a fearsome array of teeth, they are designed for grasping prey in a vice-like hold. It doesn't have shearing teeth to slice through a carcass, nor does it have tearing teeth with which and pull pieces of its victim's body apart. (By comparison, a dog's small front teeth are for tearing, and its large back teeth are for shearing). Additionally, the crocodile has a fixed tongue that cannot be used to move objects around in its mouth. As a result, the crocodile can only gulp its food down.

Photo: Crocodile thrashing its prey to kill it

For these reasons, a crocodile has two ways of consuming its prey.
1. Smaller prey are killed instantly by its pulverising bone-crushing bite and gulped down whole.
2. Larger prey are killed by grasping the victim by the arms, legs or head. The crocodile will then lift its prey high out of the water and flick its head like a whip exerting such tremendous tearing force on its victim's body that it literately rips apart. It may even drag its victim underwater and drown it first. The crocodile also uses another tactic known as the death roll'; where the crocodile rolls rapidly in the water spinning the victim and slamming it against the water until the victim drowns and hunks of meat break off its body. As the crocodile cannot chew or bite off pieces of its prey, it will continue to dismember its victim into "bite-size" chunks that it can swallow. The crocodile will pick up these smaller pieces and will juggle the food around until it's in the right position in its mouth and toss its head back, so the food slides down its throat. A crocodile can eat up to half its body in one meal when hungry. After filling its stomach, a crocodile may hide the remainder of its catch in mangroves or underwater to consume later.

A crocodile stomach is highly acidic and can dissolve most of its food, including bone. However, it cannot digest some items such as fur, hooves and turtle shells. These items accumulate in its stomach and will be excreted in its faeces undigested or turned into ‘hairballs' and regurgitated. Because the crocodile does not exert itself searching for food, its energy requirements are extremely low. It can survive for months or even years without food.

Crocodile Reproduction & Life Cycle Crocodile Eggs & Babies

Photo: Crocodile mother, baby and egg

The wet season's imminent arrival (November to April) is the signal for crocodiles to commence their courtship and mating. Males engage in posturing with conspicuous displays of virility intended to drive rival males away from possible receptive females. This male-to-male posturing may include chasing away, growling and head-slapping, which can soon escalate to serious confrontation leading to injury and even death. Females, too, are more aggressive towards other females during this time as they jostle for dominance and the attention of a suitor. Courtship takes place around September and October, and copulation which may last up to 15 minutes, may occur underwater.

Between November and March, the female selects a suitable location for her nest above any possible flood line and no further than 20m from reliable freshwaters such as a river, waterhole, creek or swamp. First, she clears an area and then scraps together plant matter, mud and earth to create an elliptical mound around 175- 220cm long and 53-80cm high. In some instances, nests are also built on floating mats of vegetation anchored to a riverbank.

The female crocodile lays between 40–60 eggs and covers them with 8-28 cm of nest material. The rotting plant matter and heat from sunlight then warm the nest and usually keep the eggs at a relatively stable optimal incubation temperature of 31-32°C. The female crocodile will remain close by to protect the eggs, which hatch in about 90 days.

The incubation temperature in its nest determines the sex of a developing crocodile. Above 32°C, and the hatchlings will be male. Below 30°C, the hatchlings will be female. (Note: We have not been able to find any credible scientific report of what the outcome would be if the temperature was between these two temperatures – say exactly 31°C).

Photo: Crocodile carrying its babies in its mouth

When baby crocodiles are ready to hatch, they make a chirping sound from inside their eggs, which alerts their mother that it is time to dig them out of their nest. She will carefully dig them out, and taking each hatching tenderly with her mouth; she will take them to the water's edge and release them. There she will protect them until they disperse over the following months.

Young hatchlings are about 28cm long and weigh an average of 71g. They are brightly patterned with dark and light bans and spots covering their bodies. These bright colours fade as the crocodile grows. They are exceptionally aggressive and will fend for themselves soon after birth, feeding mainly on small insects and other invertebrates.

Only about 1% of hatchlings will survive to reach adulthood. Male crocodiles reach sexual maturity at about 16 years of age and females at around 12.

Crocodiles keep growing throughout their lives, and their weight increases exponentially as their length increases. A mere one meter increase in length could see as much as a doubling in weight. They can live for up to 70-80 years. A crocodile in captivity named "Cassius" is at least 112 years old (in 2018).

Crocodile Predators & Threats What Eats Crocodiles?

Adult saltwater crocodiles do not have any natural predators, except for a rare shark. In a fight a hippopotamus because of their sheer size and strength could kill a crocodile. Smaller-sized crocodiles are occasionally eaten by tigers, jaguars, lions, pythons and other crocodiles. No animal in the world eats crocodiles as their primary food source. However, younger crocodiles are frequently eaten by fish, monitor lizards, turtles, and other crocodiles. Up to 75% of all crocodile eggs laid in a season do not hatch. This may be caused by flooding, overheating and under heating of the nest, poor gas exchange and desiccation of the eggs (eggs drying out).

Human encroachment into areas inhabited by crocodiles is the biggest threat to their survival. Hunting, draining of swamps and mangroves and the property developments along the shorelines are displacing crocodiles from their natural environment and increasing the risk of crocodile-human conflicts. Introduced animals such as feral buffaloes and feral pigs are also responsible for destroying wetland habitats by increasing drainage, reducing vegetation, and trampling crocodile nesting sites. Many crocodiles, especially juveniles, are caught in fishing nets and drown.

Crocodile Conservation Status Are Saltwater Crocodile Endangered?

There are many saltwater crocodiles across their vast Southeast Asian habitat, with some becoming extinct (China) and near extinct (Philippines). The IUCN conservation status for it is one of least concern.

Until 1974 saltwater crocodiles were hunted to near extinction for their skins and meat. Crocodile populations plummeted to just 3,000 in all of the Northern Territory in Australia. Their numbers have increased over the subsequent years, and it is estimated that there are about 150,000 crocodiles in the Northern Territory alone today. Crocodiles are now a protected species throughout Australia.