Jaws of steel
Douglas David Seifert encountered a crocodile in open water off Papua New Guinea and took this remarkable set of photographs. Only later did he discover just how dangerous his model was.

Should you find yourself at the water’s edge in certain coastal areas of the central Indo-Pacific, be on your guard. As if the all-too-present threat posed by squadrons of body-heat-seeking, ravenously-bloodthirsty mosquitoes (literally oozing with nasty malarial parasites) weren’t sufficient cause for caution, then take heed: watch out for the local water hazard.

In all waters, from those shallow enough barely to be called wet, to the depths of the ocean, a wader, swimmer or diver – hell, anyone getting too close to the water – has more to fear than sharks or drowning. Only a fool would dare to stick so much as a toe into the water without giving the surrounding area the most careful scrutiny. Here, the real danger is the saltwater crocodile (Crocodylus porosus).

When a saltwater crocodile hunts, it selects a victim – a water buffalo, for example. It first hears the sound of the animal, then sees it. The crocodile lies just under the surface of the water, in a ‘minimal exposure’ position. It moves slowly towards its prey, submerged, leaving the water’s surface undisturbed. It arrives at the spot where it expects to find the prey and slowly surfaces. Suddenly the crocodile, seemingly from nowhere, explodes out of the water. Its jaws thrust high, opening wide, as it finds a purchase upon the rear flank of the water buffalo. The impact of the jaws slamming shut on to the hindquarters is enough to break the leg in three places. But the crocodile does not relax its vice-like grip. The teeth dig into the flesh and hold, blood streaming down from the punctures. The water buffalo stumbles and falls. The crocodile takes advantage of the water buffalo’s floundering and begins to roll with the full weight of its body and the snake-like muscular contractions of its tail. The water buffalo becomes disoriented from the blood loss and struggles feebly. The crocodile drags the water buffalo into deeper water, where it drowns and ceases to struggle. The crocodile rips into the haunch it has separated from the now-dead water buffalo – it thrusts its head high into the air, arching backwards as it works the water buffalo leg further into its mouth and down its gullet. The crocodile then swims off to climb on to the bank of the water’s edge. Here it will rest, allowing its blood to become re-oxygenated and to warm itself in the sun. The crocodile has not eaten much of the water buffalo – crocodilian stomachs are not very large. It will return to eat more of the water buffalo after it has digested what it has consumed: a true case of biting off more than it can chew!

As a weapon, the business end of a crocodilian – the snout – is without equal in the natural world. A saltwater crocodile has cone-shaped teeth, designed to penetrate and hold, rather than to cut and grind. Should it lose any of its teeth, ready replacements lie in reserve, in sockets beneath the erupted teeth.

Extremely powerful jaw muscles further augment the effectiveness of their teeth. When the crocodile strikes and its jaws clamp on to prey, both the upper and lower sets of teeth are driven in, decisively, with a power reminiscent of a steel trap. Often a prey is killed instantly by the impact, or by severe damage such as broken bones or internal haemorrhaging. If not, it will most likely drown. A crocodile can drown its victim without drowning itself because of a flap – called a palatal valve – located at the rear of its mouth. Once a crocodile enters the water, breathing is done through its nostrils, the palatal valve closed so that the crocodilian can open its mouth without water rushing down its throat.

‘Suddenly the crocodile, seemingly from nowhere, virtually explodes out of the water’

See you later: top, saltwater crocodile heads for cooler waters; above, crocodiles may remain still for hours
Curiously, in spite of the tremendous crushing power of the jaw muscles, the muscles used to actually open the jaws are extremely weak. Carnival sideshows with ‘alligator wrestling’ demonstrated long ago that the snout can be held shut with very little effort – a sturdy rubber band can do the trick. But once they’re open, watch out!

Even though the jaws possess enormous power, crocodiles are quite capable of exerting precise, even gentle control of them. When a female crocodile digs her hatchlings out of the nest, where they have been incubating for several months, she gently gathers them into her mouth and transports them to the water’s edge.

Although there are other species of crocodile that are considered dangerous to man, it is the saltwater crocodile that has been responsible for the greatest number of human fatalities. In the period from 1980 to 1990 this only amounted to 12 deaths in Australia, an area with more than its fair share of saltwater crocodiles. It is more of a threat to humans than other crocodiles because of its great size (the largest verified specimen is 6.7m), its deadly and efficient hunting strategy, and its wide geographic distribution in marine, brackish and freshwater habitats.

The geographic range of saltwater crocodiles is extensive, from southern India to Fiji; from Australia to Vietnam and the Philippines. And, although essentially a coastal inhabitant, it can be found inland (they have been found as far as 1,100 km upriver in Papua New Guinea) – or far out to sea (one was found at Cocos (Keeling) Islands, 970km from the closest landmass).

Crocodiles are ‘cold blooded’ but this does not mean their blood runs cold. It means that they are physiologically unable to regulate their body temperatures, and must utilize cooler water temperatures and warming sunlight to adjust their body temperature. The advantage is that less energy is expended on controlling body temperature, so it is not necessary to eat as much or as often as some warm-blooded animals.

Often, a crocodile at rest by the water’s edge is so motionless as to appear dead – it betrays no signs of life, not even, apparently, the very process of respiration. But the crocodile is not dead, not even close. It is merely warming or cooling itself. (The reason it does not appear to breathe is that inhalation occurs from the movement of its internal organs forwards and backwards, like a piston.)

From this seemingly sleepy state, crocodiles may leap up to 2m into the air. They function very effectively on land; they have the ability to ‘sprint’ at speeds of up to 18kmph, an activity that is used to surprise unwary prey.

A juvenile crocodile finds its prey using sensory pits in its jaws and its diet consists of small prey such as insects, as well as prawns and crabs. It is only once a crocodile reaches 3m or longer that virtually everything is on the menu: dogs, pigs, wallabies, other crocodiles, water buffalo, cattle, horses, and, of course, man.

To catch larger prey, waterborne stealth hunting is highly effective. Crocodiles work under a distinct advantage. Their anatomical structure allows them, when submerged, to display a ‘minimal exposure’ posture. Only their eyes, nostrils and the top of the skull remain visible above the surface. No indication of the size or the shape, the menace of the tooth-filled snout nor the animal itself lying below is betrayed – just a pair of unblinking eyes and what could easily be mistaken for a drifting piece of wood.
Crocodile rock: above, crocodiles can move quite effectively on land and underwater

Top, a crocodile uses its nostril to breathe when on the surface; above, a crocodile's tail helps it to swim
Saltwater crocodiles are highly dangerous and should be feared. So, should you find yourself somewhere remote, on a lonely stretch of sand, trudging through ankle-deep water, and everything seems still and quiet, too quiet ... look around, and pay careful attention to the slightest ripple on the water.
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