Animals The Crocodile

Published on March 10th, 2010 | by Yellow Magpie

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The Crocodile: Adapted Physically And Mentally Beyond Compare

The Crocodile Photo By Trisha M. Shears

Picture this scene, it is a beautifully tranquil night, an effervescent shimmer is being reflected off glass-still, moon-lit water and all is serenely quiet around the riverbank. Something in the distance disturbs the water, ripples distort and fragment the pristine surface.

Suddenly, two piercing white eyes break through the waterline and a cavernous blackness imposes itself on the surrounding area. On either side of the darkness rests two neat rows of jagged flesh-puncturing teeth. The crocodile.

Chances are when we think of crocodiles, primeval feelings of fear and terror flood into our consciousness. The sight of the crocodile is one of the most awe-inspiring sites in nature. A spectacle that is at once both instantly memorable and at the same time fear-inducing.
What is it about crocodiles that inspires such reactions? Are they really just a killing machine or is there much more to them than what is on display?
The Crocodile: Nile Crocodiles Creative Commons ShareAlike Licence

The Crocodile: Nile Crocodiles Creative Commons ShareAlike Licence

 

A One-Off Brain

For years there has been a general consensus that crocodiles possess little in the way of cerebral prowess. Instead it was thought that they relied upon rather primitive instincts to survive and catch prey. More recent evidence has completely dismissed this.

Crocodilians have a complex brain with a cerebral cortex. This cerebral cortex is not found in any other reptile. In fact, the only other animals which have a cerebral cortex are higher mammals such as humans.

It is widely believed that this one-of-a-kind brain is largely responsible for the animals being so intelligent. Crocodiles, especially when going after large prey, hunt in groups. In order to do this successfully, a keen intelligence and good communication skills are necessary.

Crocodiles are quite social creatures and they have different hierarchies so that each member has a place in the group. This comes to the forefront when they are feeding on large animals. In these situations each crocodile waits their turn to feed in an orderly, regimented manner.

Saltwater Crocodile At St. Augustine Alligator Farm Photo By Molly Ebersold

Saltwater Crocodile At St. Augustine Alligator Farm Photo By Molly Ebersold

Excellent Communicators

Despite what the dominant stereotypes surrounding crocodiles suggest, they have excellent communication skills. Their use of body language and the presence of a larynx means that they are surprisingly sophisticated at conveying their wants and needs. This faculty is especially useful for settling territorial disputes.

These communication skills are heavily tested during  the mating season. Generating low guttural sounds, that would not be out of place in Jurassic Park, male crocodiles are especially vociferous. Exhaling air through their vocal boxes, they cause muscles in their body to vibrate resulting in the water around them ‘dancing’. Although these sounds are difficult to hear with human ears, underwater they travel large distances and magnetically attract females.

Crocodiles also watch and learn. They pay keen attention to what other animals are doing and they observe patterns of behaviour and wait for opportune moments. This is why people who live in close proximity to crocodiles are warned to never regularly approach the same point in a river to get food or water, as a crocodile will learn their routines and be waiting for them the next time they visit.

The Crocodile: Saltwater Crocodile Resting On A Riverbank Photo By Paul Thomsen

The Crocodile: Saltwater Crocodile Resting On A Riverbank Photo By Paul Thomsen

Tender And Caring Social Creatures

Crocodiles are social creatures. Contrary to the popular imagination, crocodiles can be incredibly tender and affectionate. This is especially invaluable for any social creature and crocodiles are highly gregarious.

Male groups often congregate together on riverbanks, this is especially true of the Nile Crocodile, with each one having his place carefully allocated according to a hierarchy. Females too, acknowledge authority figures and display their respect and submission to dominant males by raising their head out of the water to show their vulnerable throats.

The Crocodile: Muggar Or Marsh Crocodile In India Photo By Karunakar Rayker Creative Commons Share Alike Licence

The Crocodile: Muggar Or Marsh Crocodile In India Photo By Karunakar Rayker Creative Commons Share Alike Licence

Before mating even begins, the male and female gently touch each other. Although this behaviour may seem quite typical for most animals, it is unheard of in other reptiles.

Considerate Nest Building And Careful Nurture

The tenderness that is part of crocodilian life is transferred to nest building and caring for the young. The mother builds the nest and lays the eggs in a carefully chosen site. Their eggs only develop if they are incubated at 27 to 34 degrees Celsius no matter what the terrain or geographical location.

Building a nest to such stringent requirements is such a complicated procedure that no one knows how it is achieved. All is known is that it is achieved, despite the seemingly great odds. Perhaps even more amazing is the fact that temperature determines the sex of the young. Even a minute change such as just half a degree from the top of the nest to the bottom can result in different sexes being born.

When the eggs hatch the young crocodiles call out. Hearing the cries of its offspring the mother digs out the young and delicately scoops them up into her mouth carrying them off to the safety of the water where they are placed in a nursery pool. During the nursery period, which can last up to five months, the mother will not eat any food and instead devotes all her time and energy into protecting her young from both predators and other crocodiles.

However, despite all the protection afforded to the young by their mother, only two out of every 100 reach adulthood sometimes even less make it depending on the species.


A Super Sleek Armour Clad Body

To compliment their considerable social and intellectual skills, crocodiles have physiques which are the epitome of efficiency. Their slender tapered bodies are perfectly streamlined to cut quickly through the water with the minimal of effort. Powered by short flicks of its tail, a crocodile can reach bursts of speeds that reach in excess of 35 kilometres per hour (19 miles per hour).

The indented, grizzled appearance of a crocodile actually serves two functions. Made of a keratin and bone armour, its outer skin provides the tough protection that the animal needs. Crocodiles are fiercely territorial creatures and because of this they often engage in combat with other crocodiles.

The second reason for the indentations is that it minimises the effects of water resistance. This allows the animal to cut through the water with the minimal of effort, not at all unlike the way a golf ball’s dimples allow it to fly through the air faster. But more importantly, because the crocodile does not disturb the water, prey which would otherwise would be too fast to catch, are pounced on unawares.

The Crocodile: Gharial Crocodiles On A Riverbank In Nepal Photo By Wimbex

The Crocodile: Gharial Crocodiles On A Riverbank In Nepal Photo By Wimbex

Because the crocodile is cold-blooded, having a thick armour-coated body should pose it problems when it is trying to warm itself under the sun’s rays. To get around this problem, the bones which make up its armour, are defused with blood vessels which run throughout them. Much of these vessels run close to the surface, thus allowing the crocodile to be optimally heated by the sun.

In fact, so efficient are crocodiles, they can thermoregulate their bodies keeping their core at a constant temperature.  They can do this because their heart, like a human’s, has four chambers. Other reptiles have just three. All of this allows them to hunt at night at a time when other reptiles have very little energy. Great White Sharks can theormoregulate their bodies too.

Their super-efficient bodies also allow them to go without food for long periods.

A counter-shaded body also assists them when hunting their prey. Their ventral side, or underbelly, is a light shade which helps to disguise them when they are above their prey. While their dorsal side is a dark colour which serves to mask their bodies while they are below their prey.

The Most Powerful Jaws In The Animal Kingdom

Perhaps the most obvious of all crocodilian features is the enormous mouth outlined by rows of strong lethal teeth. Of all the numerous animals in the world, the crocodile has the most powerful bite and this includes the White Shark or ‘Great’ White Shark. Its massive fast-reflex jaw muscles can generate a 350 kilogramme force per square centimetre (5,000 pounds per square inch).

Capable of ripping a large animal such as wildebeest in half, the crocodile has perhaps the most cleverly adapted jaws in the animal kingdom. The secret to its powerful bite is the colossal muscles it uses for closing its mouth. These muscles receive relatively little oxygen which means that they can generate huge forces almost immediately.

But because they are not richly oxygenated they lack endurance and tire quite quickly. The muscles are incredible large – over ten times larger than the biceps of a champion body-builder. They are so powerful that the animal has to have other muscles to counteract the forces otherwise its jaw-bone would be fractured under the pressure.

The downside of having such huge jaw-closing muscles is the space that they take up. Perhaps because of this the muscles that a crocodile uses to open its jaws are very small. As a result, they are extremely weak and can be easily held closed.

The Crocodile: Indian Gharial Crocodile Photo By Justin Griffiths

The Crocodile: Indian Gharial Crocodile Photo By Justin Griffiths

Crocodiles are ambush predators. The secret to their success is their low-slung profiles and their ability to almost disappear in the water. Their jaw muscles are not only amazing in their own right, but from an engineering perspective they could not be better positioned.

The large muscles that close the jaws are low down on the crocodile’s neck, much lower down than in other animals, which does not distort its profile. And because the muscles for opening its mouth are small, they are perfectly located above the closing muscles so as not to distort the crocodile’s sleek, slender profile.

The Crocodile: Nile Crocodile Photo By Sarah McCan

The Crocodile: Nile Crocodile Photo By Sarah McCan

The Crocodile: Death Roll And Drowning

Unlike a lot of other carnivores, crocodiles do not have razor-sharp teeth. Instead their teeth are large and round. Having these type of teeth may be a hindrance to other animals, however, for a crocodile they are advantageous. This is because of the animals unique method of feeding, the ‘Death Roll’.

When crocodiles have grabbed their prey they go into a series of rotations called a death roll. This twists their prey’s body and rips it apart making it easier for the crocodile to eat. They need strong and relatively blunt teeth, as opposed to sharp fangs, so that they can cope with the huge centrifugal forces that the death roll places upon them.

However, how crocodiles can do a death roll without drowning has been a mystery until recently and reveals just how well-adapted these animals truly are. The crocodile has several anatomical features which enable it to avoid drowning while doing a death roll. Their nostrils have special flaps which open and close preventing water from entering their lungs.

A large tongue-flap covers both openings in the larynx, or voice-box, and its windpipe connecting to the trachea. This flap prevents the crocodile from taking in water when it has its teeth firmly wrapped around its prey. Not only that, when the flap is closed an alternative air route is formed between the nostrils and the lungs.

The tongue-flap also has another ingenious function. While laying underwater on the river bed, the crocodile can catch fish by creating a current which draws in fish. It does this by rapidly dropping its tongue flap which causes water to rush into its normally covered openings. This movement of water sucks the fish in providing the crocodile with a handy meal.

The Crocodile: Mugger Or Marsh Crocodiles Photo By Kmanoj

The Crocodile: Mugger Or Marsh Crocodiles Photo By Kmanoj

Ultra-Powerful Digestive System

Crocodiles possess one of the most powerful of all digestive systems. Their diet of whole animals means that they need to be able to digest teeth, bone and sinew. Because of the huge chunks of meat that they routinely swallow, their trachea is reinforced with large rings to prevent the animal from becoming asphyxiated as the oesophagus gets distended while eating.

Their trachea also contains another variation not found in other animals. It is long and flexible which allows it to move to one side to accommodate the massive meals.

Crocodiles posses a unique heart which has an extra aorta artery. It is now thought that this extra feature is responsible for aiding the crocodiles rapid digestive system. It is believed that, when needed, a valve in the heart opens up moving carbon-dioxide rich blood, which is highly acidic, from all over its body to the stomach.

This produces much needed acid. It is this extra acid which aids digestion and allows the animal to quickly breakdown hard substances such as bones within a matter of a week or two.

The Crocodile: Large Saltwater Crocodile Photo By  MartinRe at the English language Wikipedia Creative Commons ShareAlike Licence

The Crocodile: Large Saltwater Crocodile Photo By MartinRe at the English language Wikipedia Creative Commons ShareAlike Licence

Massive Lungs

Crocodiles’ hunting modus operandi is stealth-based. To do this effectively it needs to be able to stay submerged for relatively long periods of time. To achieve this, crocodiles possess very large lungs. In fact, crocodilian lungs have four times the capacity of human lungs. This, together with their bodies’ overall efficiency, means that they can stay underwater for up to half an hour.

They can also relocate their liver pushing it backwards giving their lungs even more room to spread out. In fact, it is now thought that their liver acts as a buoyancy tank allowing the crocodile to control its depth in the water.

Sensitive Senses

The crocodile is structurally amazing allowing it to have a dynamic range of senses while it is under and above the waterline. Above the waterline, its head rests above water creating a very low profile that is difficult to detect. Its nostrils protrude just above the surface allowing it to breathe. Its eyes provide good vision in both daylight and during nighttime. They are covered by a protective membrane which closes when the animal is in the water.

Its ears also rest above the waterline allowing it to hear sounds that are transmitted through the air. Not only that, crocodiles possess small black dots littered across the sides of its head. These are pressure sensitive domes that allows the crocodile to detect the slightest disturbance in the water. They also possess a very acute sense of smell and they can detect odours from a far away as seven kilometres (four miles) or more.

The Crocodile: Nile Crocodile Photo By mathKnight And Zachi Evenor Creative Commons ShareAlike Licence

The Crocodile: Nile Crocodile Photo By mathKnight And Zachi Evenor Creative Commons ShareAlike Licence

Powerful Propulsion On Water And Land

In the water, crocodiles are propelled by their powerful tail. Comprising half their body-length, their tails are almost completely composed of solid muscle. Large protrusions made of keratin-covered bone grip the water, rapidly pushing the crocodile to where it wants to go. Its tail moves in ‘S’ shapes rather like that of a typical snake.

These movements, in tandem with occasional assistance from its feet, allow the crocodile to travel in excess of 35 kilometres (19 miles per hour).

The Crocodile: Saltwater Crocodile (Stumpy) Photo By J. Patrick Fischer

The Crocodile: Saltwater Crocodile (Stumpy) Photo By J. Patrick Fischer

On land, crocodiles are surprisingly agile. Their normal gait is known as the belly-crawl. When moving like this their stomach scraps the ground as their body is dragged along by their feet. This is rather like how a surfer uses his arms to push the surfboard through the water except the crocodile uses his hind legs the same way it uses its front ones. When they want to move at a faster rate they lift their stomach off the ground and engage the ‘high walk’.

If speed is of the essence, smaller-sized crocodiles can ‘gallop’ or ‘bound’. When they do this their body is elevated high above the ground and they push their limbs rapidly powering their body off the earth. This motion is not unlike how a swimmer does the butterfly stroke.

Once again the key difference is that instead of just using their arms, like a swimmer,  the crocodile uses both sets of limbs in the same manner. One particular crocodile has been recorded travelling at a speed of 17 kilometres per hour (11 miles per hour) on land.

However, the gallop can only be used for a very short period of time and because of the crocodiles’ rather low metabolism its can take hours for the animal to recover.

The Crocodile: Siamese Crocodiles Creative Commons ShareAlike Licence

The Crocodile: Siamese Crocodiles Creative Commons ShareAlike Licence

The Mysteries Of A Super Immune System

Crocodilians live in some of the most insanitary conditions. From filthy unclean waters that would kill off most species of fish to uninhabitable sewers, crocodiles can be found in places that would kill nearly any other animal. Added to this is their hazardous lifestyle which can see them injured when going after large prey.

Indeed they can sometimes be maimed when fighting with fellow crocodiles. So how come they seem to show no ill-effects? What is it about them that makes them so tough and obdurate?

The answer resides in their blood. Crocodiles have one of the most powerful immune systems of any animal. Because of this, they can comfortably fight off infections and other ailments that would result in death for other species. Scientists have run tests to see just how powerful their immune systems are. Pouring a drop of  crocodiles blood on top of a culture of the MRSA Superbug (which is immune to all antibiotics), resulted in the MRSA cells being killed.

Perhaps this highlights best of all the benefits of protecting crocodiles for humanity.

The Crocodile: Gharial Crocodile Photo By Cliff

The Crocodile: Gharial Crocodile Photo By Cliff

Vital Statistics

  • Male Saltwater Crocodiles can grow up to six metres (20 feet) in length.
  • The saltwater crocodiles can weigh in excess of 1,000 kilogrammes (2,200 pounds).
  • They have a life expectancy of up to 70 years. In fact one freshwater species, nicknamed ‘Mr Freshy’, is estimated to be over 130 years of age.
  • Various species of crocodiles are found in all tropical regions.

This creature has managed to survive almost completely unchanged for the best part of 100 million years. It has outlasted the dinosaurs, it has seen mankind through all its evolutionary steps, and perhaps it may outlast us.

One thing is certain, this incredible animal has not only the most perfectly adapted body, which it utilises with the greatest of efficiency, but it possess a keen and sharp intelligence which harnesses its physical strengths. This is an animal that really has adapted physically and mentally beyond compare.


Recommended Reading

Crocodiles and Alligators of This World explores all the different species of crocodilian.

Amazon.co.uk
For people living in Ireland or the United Kingdom, you can access Crocodiles and Alligators of This World here.

Amazon.ca
For those who live in Canada, you can obtain Crocodiles and Alligators of This World from here.

Amazon.de
For Germany: Crocodiles and Alligators of This World.

Amazon.fr
For France: Crocodiles and Alligators of This World.


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One Response to The Crocodile: Adapted Physically And Mentally Beyond Compare

  1. Beautiful but deadly creatures!

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