The saltwater crocodile is the world's largest and deadliest reptile. Growing up to 6 meters in length and weighing as much as 1,000 kilograms a crocodile is not a creature you want to confront. An aggressive carnivore, it is one of nature's most ferocious and efficient killing machines. It can overpower almost any animal that enters its territory. Saltwater crocodiles are found throughout the north-eastern coastline of Australia and also in south Asia. The ancestors of the crocodile first appeared on earth about 230 million years ago – way before dinosaurs. They have remained essentially unchanged ever since.
The saltwater crocodile is an aggressive cold-blooded, amphibious, carnivorous reptile with scaly skin and a broad snout crammed with pointed jaggered teeth. Its eyes, ears and nostrils are set high atop its head so it can be active with its body submerged and only these parts of its body above water. It has a broad flattish body with a long streamlined muscular tail and short limbs with clawed feet. It has the largest brain of any reptile and is thought to be the smartest.
The crocodile is an ambush hunter well adapted to its water environment, where it lies in wait for its prey either partially or totally submerged. 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 also has a second pair of eyelids that are transparent and protects its eyes while it is underwater. A crocodile may appear slow and lethargic, but it can swim at speeds of up to 32 kph and run for short distances at speeds of up to 18 kph.
Crocodiles are Birds?
While crocodiles (crocodilians) are classified as reptiles, they are actually more closely related to dinosaurs and birds than to animals classified as reptiles. They were probably classified as reptiles because of their dry scaly skin and lizard-like looks.
While usually referred to as the Saltwater Crocodile, its correct common name is Estuarine Crocodile. Other names by which it is known include Indopacific Crocodile and the Australian strine name 'Saltie'. Its scientific name is Crocodylus porosus.
Crocodiles are Cold-Blooded
Crocodiles are cold-blooded. For this reason they cannot regulate their body temperatures internal. They rely on their habitat to provide them with an environment in which they can maintain a body temperature in the range of 30-33C. They regulate their body temperature by moving back and forth between warm and cool parts of their environment. In colder weather they bask in the sun to heat up, and in hot weather they seek shaded, cool areas to avoid overheating. When basking they position they bodies to optimise the heating or cooling they require. Crocodiles are frequently seen with their mouths agape. This mouth wide-open posture is used to keep their bodies, especially their brains, from overheating. By opening their mouths and exposing the skin inside, they cool themselves by evaporative cooling through their mouths. Mouth gaping is also a behavioural posture that is not fully understood.
Crocodile Size and Age
A male crocodile can grow to lengths of over 6 m and possibly even 7 m. They are typically 3-5m in length with males growing much larger than the females who rarely grow bigger than about 3m. They range in colour from golden tan to grey to black with a mottling scaly skin. They have cream-coloured bellies. A fully grown male can weigh as much as 1,000-1,200 kg. Crocodiles keep growing throughout their lives and its weight increases exponentially as its length increases. A mere one meter increase in length could see as much as a doubling in weight. They can and live for up to 70-80 years. A crocodile in captivity named “Cassius” is said to be at least 112 years old (in 2018).
A crocodile’s forward-facing eyes are located on top of its head so it can see above the water as it cruises the water. Its eyesight is as keen as that of an owl and it can probably see some colour. Because of their vertical pupils which can open much wider to let in more light than round pupils, crocodiles also have very good night vision. Special transparent eyelids enable it to see underwater when submerged. The crocodile produces tears to clean its eyes and prevent bacterial growth.
A crocodile’s ears are located just behind its eyes (see photo). These slit-ears, which close when the crocodile submerges, lead to well-developed inner ears which gives the animal very good hearing. Crocodiles can even hear their young calling from inside their eggs many meters away.
The crocodile's nostrils are located on top of its snout which allows it to keep breathing while keeping its body submerged under water. It has special organs in its snout that gives the crocodile a great sense of smell. It has nose flaps that close to prevent water from entering its lungs when it submerges itself.
The crocodile has a rounded wide snout with a huge mouth. Its massive jaws, when closing, can exert '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 devour almost any animal. While the crocodile has extremely powerful muscles to close its jaws, those to open them are it extremely weak. So weak in fact that a person could literally hold them shut with his bare hands.
Its mouth contains between 40-60 large teeth. The fourth tooth of its lower jaw is visible over the lip of its upper jaw. Its “holding teeth”, designed for grasping and holding on to prey, are strong and pointed but not sharp. Other teeth are razor sharp and designed to chomp through its victim.
A crocodiles replaces its teeth throughout its life. Teeth replacement occurs over time, in “waves”, starting from the back to the front in young crocodiles and front to back in older ones, with each alternate tooth being replaced. Crocodiles may replace as many as 8,000 teeth in their lifetime.
A crocodilian does not have sweat glands and uses mouth gaping to release heat from its body - similar to a dog panting. Its tongue which is attached to the bottom of its mouth does not move and has special glands to get rid of excess salt. It also has taste buds to taste its food. The crocodile can block off the back of its throat with a large fleshy flap of skin to prevent water from entering its lungs and stomach when it opens its mouth under water.
The crocodile has rough studded scaly skin covering its entire body. The colour of the upper part of their bodies vary from tan, greenish-drab to almost black. Its belly is cream coloured. Their tails are usually grey with dark bands. Juveniles have bright patterns with dark spots and bands that are lost as the animal ages. Special sensors embedded in its skin act like motion detectors enabling the animal to detect what is around it. This is obviously very useful when searching for prey in murky water and at night.
The crocodile like other reptiles has legs that protrude outwards from the side of its body (rather than downwards and under as in mammals). These legs are short with webbed rear feet. In water its only uses its feet at very slow speeds for an occasional paddle, to steer and also to maintain its position in the water. When floating on or just below the water surface the front and back legs splay out to act as stabilisers to prevent the crocodile from rolling – tipping over and capsizing in the water. When swimming the crocodile usually tucks its legs against its body to streamline its body and reduce drag but uses them like rudders for steering. On land, the crocodile slides along on the ground using its legs to propel itself or heaves itself up on its four legs to move. It can gallop for very short distances at speeds of up to 18 kilometers an hour.
The saltwater crocodile has an extremely long, powerful and streamlined tail that is laterally flattened. Meaning it is much taller than it is wide, giving the tail a large surface area to push against the water as the crocodile whips its tail from side to side in a '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. The crocodile stores fat in its tail and can draw down on it in hard times, going without eating for as long as two years in the case of some large adults.
Crocodile Attack Statistics In Australia
• There are approximately 5-10 crocodile attacks in Australia each year.
• 25% of all attacks were fatal. That is 1-2 people each year.
• 81% of attacks were on people swimming, wading or at the water's edge.
• Crocodiles 2.7-5.1 m in size were responsible for fatal attacks. The average size of the crocodile was 4.3m.
• Crocodiles as small as 1.7m attacked humans.
• Nearly 71% of the humans attacked were male.
• 74% of the attacks occurred during the day.
• Nearly 54% of all attacks took place during the wet season (Nov-Apr).
Saltwater Crocodile – Danger to Humans Is the Crocodile Dangerous?
Are crocodiles dangerous? Absolutely!
The saltwater crocodile is one of nature's deadliest and most efficient killing machines. A hyper-carnivorous apex predator, it can overpower almost any animal that enters its territory. Humans are just food, and fair game for a large crocodile.
Any person foolish enough to enter a crocodile infested area, such as a river or creek, has a very high probability of being taken by a crocodile with little chance of escaping without horrific injury, or being torn apart and eaten.
Most attacks occur on people close to the water such as swimmers, people canoeing or bending down at the water’s edge. This low profile seems to elicit a greater predatory response than when a person standing upright.
The crocodile is an ambush predator that uses stealth to approach its prey. Swimming with most of its body submerged it silently positions itself within range of its prey and then it uses its powerful tail and hind legs to leap out of the water and pouch on its prey.
Grasping their victim with a bone crushing bite usually by an extremity, such as the arms, legs or head, the crocodile will lift its prey high out of the water and flick its head like a whip exerting such tremendous tearing force and literately ripping its victim apart at the point of its brutal bite. It may also drag its victim below the surface and drown it and may also use a 'death roll'; where the crocodile rolls rapidly in the water spinning the victim and slamming it against the water until hunks of meat break off its victim.
Attacked by Crocodile Video
A crocodile cannot chew or bite off pieces of its prey, so it will continue to dismember its victim into "bite size" chunks by continuing to whip its victim till it falls apart or by chomping on it. The crocodile will pick up these smaller pieces and will juggle the food around until it is in the right position in its mouth, and then toss its head back so the food slides down its throat.
Crocodiles as little as 1.7m have been known to attack humans, but most fatalities are caused by animals that are about 4m. A human is very unlike to survive a well targeted assault from an adult crocodile larger than 4 meter in length.
Saltwater Crocodile – Attack Prevention How to Prevent from Being Attacked
Poke a Crocodile in the Eye
The only defence you may have if attacked by a crocodile is to poke it in its eyes and hope it will let go.
Also if you flash a touch light and see glowing orange eyes you know you are seeing a lurking crocodile.
A few simple precautions can make any visit the areas known to be inhabited by crocodiles safe.
• Obey all crocodile warning signs – they are there for a reason – to protect you.
• Do not assume it is safe to swim if there is no warning sign. A crocodile may lurk in any shallow pool, drainage canal or even a ditch, especially if the water is murky.
• Do not allow pets to roam near the water.
• Supervise children at all times and explain the dangers.
• Do not walk around at night especially close to water.
• When camping, choose a site well away from the water, preferably on high ground. If camping on a beach, be aware that crocodiles sometimes come ashore at night.
• Stand back at least 3m from the water’s edge. If fishing, cut your line if it get entangled rather than wade in.
• Never leave animal carcasses, fish guts, raw meat, etc near where people swim, fish or moor boats.
• Do not dangle your arms, legs or body over the side of a boat. You may get it chomped off or get dragged into the water by a lurking crocodile.
• Never present a low profile to a crocodile. Most attacks occur on swimmers or on people canoeing or bending down at the water’s edge. This low profile seems to elicit a greater predatory response from a crocodile than from a person standing upright.
Saltwater Crocodile – Habitat & Distribution Where Do Crocodiles Live?
The saltwater crocodile is found throughout Southeast Asia from India through to Vietnam, the Philippines and down to Australia.
In Australia, the saltwater crocodile is found along the coastal regions of the top of northwesters Western Australia from Broome through the Northern Territory to Gladstone in south-eastern Queensland. It is also found on some offshore islands off the Northern Territory and Queensland coasts.
The saltwater crocodile can live in both freshwater and saltwater habitats including rivers, estuaries, creeks, mangrove swamps, coastal marshes lagoons and billabongs (waterholes) and is often found swimming along coastlines. Crocodiles do not seems to inhabit regions higher than 250 m above sea level.
Being cold blooded they move to warm climes when temperatures are too cold. Australian saltwater crocodiles will generally spend the tropical wet season in freshwater areas such as swamps and river and as the weather warms up they move downstream to estuaries and coastal areas and even the open ocean. While a crocodile prefers travelling in water, there are instances where it will travel overland in search of new territory.
Crocodiles are territorial and will compete aggressively with others for territory. The most dominate male will usually occupy the prime "water front" real estate. Lesser crocodiles will occupy more marginal areas. Crocodiles hibernate or become dormant in burrows dug in the sides of river banks during colder months or during periods of drought.
Crocodiles have excellent homing instincts. Some crocodiles relocated by humans to different habitats as far as 400km away were found to have returned home within three weeks. They have also been known to make epic ocean crossings, traveling many hundreds of kilometres in the open ocean. They will frequently swim up unobstructed rivers and streams to new areas, sometimes using seasonal flooding to get to hard to reach locations.
Saltwater Crocodile – Diet How a Crocodile Hunts and Feeds
What’s on the Crocodile's Menu?
The crocodile are opportunistic carnivorous predator that catches its prey in water or along a shoreline. It does not actively hunt, instead it waits patiently for prey to come its way. (There is some logic in this strategy. Because the crocodile does not exert itself searching for food, its energy requirements are extremely low, making it less needy of frequent meals).
The crocodile is predominantly nocturnal but will also hunt during day should an opportunity arise. It not a fastidious eater and will consume any animal – dead or alive. This may include fish, turtles, frogs, birds, crustaceans, pigs, buffaloes, dingoes, flying foxes and other flying animals (sometimes snatched out of the air), domestic animals, sharks, dugongs, kangaroos, land birds such as emu, etc. The size of its prey is only limited by the crocodile's size and its appetite. Juvenile crocodiles start off on a diet of insects, small fish and small mammals and as they grow older progress to larger and larger prey.
Crocodiles are also cannibalistic, usually during the wet season (September - March). Dominant males may attack and eat smaller male crocodiles to defend and re-establish their territories.
How Crocodiles Hunt & Kill Their Prey
The crocodile predominately hunts in water. It either cruises its waterway habitats or stays relatively motionless in the water until an unwitting animal comes within striking range. The crocodile will move quietly in to position, and will then launch itself with tremendous speed and power out of the water to grasp its prey in its powerful tooth-filled mouth.
How Crocodiles Eat Their Food
A crocodiles eating habits are best described as a 'chomp and gulp' approach. While it has a fearsome array of teeth, they are basically designed for grasping prey in a vice-like hold. A crocodile does 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. (In comparison, think of the small front teeth of a dog for tearing and its large back teeth for shearing). Additionally the crocodile has a tongue that is fixed and cannot be used to move objects around in its mouth. The crocodile can only gulp its food down.
For these reasons the crocodile has two ways of consuming its prey.
1. Small 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 at the point of its brutal bite. It may even drag its victim underwater and drown it first. The crocodile 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 swallows small stones that help it grind up food in its stomach. Its stomach are 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.
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. Having a very slow metabolic rate, it can also survive for months or even years without food.
Saltwater Crocodile - Reproduction Crocodile Babies
Courtship & Mating
Male crocodiles reach sexual maturity at about 16 year of age and females at around 12. The imminent arrival of the wet season (November to April) is the signal for crocodiles to commence their courtship and mating. Males engage in posturing with conspicuous displays of virility intended on driving rival males away from possible receptive females. This male to male posturing may include chasing away, growling and head slapping. This can soon escalate to serious confrontation leading to injury and even death. Females too become more aggressive towards other females during this time as they too 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 take place underwater.
Sometime between November and March the female selects a suitable location for her nest above any possible flood line and no further than 20 m from reliable freshwater such as a river, waterhole, creek or swamp. 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 over with 8-28 cm of nest material. The rotting plant matter and heat from sunlight then warms the nest and usually keeps the eggs at a relatively stable optimal temperature of approximately 31-32°C for incubation to take place. The female crocodile will remain close by to protect the eggs until her eggs hatch typically in about 90 days.
Temperature and the Determination of the Sex of Babies
The sex of a developing crocodile is determined by the incubation temperature in its nest. 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 temperature – say exactly 31°C).
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 be released them from their nest. She will carefully dig them out of their nest, 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 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.
Saltwater Crocodile - Threats & Predators What Threatens the Saltwater Crocodile?
What are a Group of Crocodiles Called?
The collective noun for a group of crocodiles depends on if they are on land or water. On land they are 'a bask of crocodiles'. In water they are ' a float of crocodiles'.'
A number of factors affect the survival of the saltwater crocodile in Australia.
It is estimates that up to 75% of all crocodile eggs laid in a season do not hatch. The reasons for this may include, flooding, overheating and under-heating of the nest before hatching, infertility, poor gas exchange and desiccation of the eggs (eggs drying out).
While large adult saltwater crocodiles do not have any natural predator (with the exception of a rare shark and humans), juveniles crocodiles face a perilous existence. Young crocodiles are frequently eaten by fish, monitor lizards, turtles and other crocodiles.
Human encroachment onto areas inhabited by crocodile is the biggest threat to their number. Waterfront homes, draining of swamps and mangroves and the property developments along the shorelines are displacing crocodiles from their natural environment and increase the risk of crocodile-human conflicts. Introduced animals such as feral buffaloes and feral pig are also responsible for destroying wetland habitats by increasing drainage, reducing vegetation, trampling crocodile nesting sites.
Many crocodiles, especially juveniles are caught in fishing nets and drown each year.
Saltwater Crocodile - Conservation Status Is the Saltwater Crocodile Endangered?
There are large numbers of 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. 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.
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