The crocodiles have outlasted the dinosaurs and lived for about 240 million years. Has man learned to live with it? Here are some facts revealing the true nature of crocodiles.
Since time immemorial, man has feared the different forces of nature fearing the creations of God, as well, in the process. Alligators and crocodiles, the two very primitive and dangerous creatures, had been the objects of fear ever since. Out of this fear they have placed them in a much higher position near to God and has been worshipped by many.
Ancient Egyptians were known to present offerings to their crocodile-god, Sobek, and mummified crocodiles were buried in tombs with people of high standing. The Egyptian sculptures and drawings on walls show a certain God with a crocodile head who had human worshippers bending down in front of him offering their prayers. In other parts of the world - Africa, India, the Philippines, for instance - the crocodile has been held in similar reverence and the aborigines of Australia believed that one of the largest rivers was made by a crocodile that chewed the land to create the river bed.
Time changed and man started hunting and killing crocodiles and alligators, partly because they were a threat to his domestic livestock and also in many areas, for food. Crocodile skin made a place in the fashion world no sooner and widespread killing of these animals began to meet man's various needs posing a threat to their population. About 20 million crocodiles have been killed over the last 50 years. The skin became a very popular fashion leather and the teeth were considered holy in certain regions in India. This forced the governments of various countries to impose laws to stop killing these animals thus preventing their extinction from the face of the earth. The Nile crocodile has disappeared from many of its northern habitats in Africa. The Indian gharial may already be extinct in the wild.
Even before the appearance of man on this blue planet, there evolved the crocodiles. It was about 200 million years ago when they were first cited. It was the period when the giant reptiles - the dinosaurs ruled, when crocodiles came on stage wholly as land animals with slightly longer legs and shorter snouts than the ones we know now. Fossilized evidences show that they evolved to a more varied lifestyle and thus have started living a semi-aquatic life with some features similar to that of mammals and birds other than that of reptiles.
About 65 million years ago, the Mesozoic era saw the last of the dinosaurs before they became extinct and probably due to Darwin's "Survival of the Fittest" theory, these crocodiles and alligators adapted themselves to the changing atmosphere with evolution starting from about late Triassic and went on merrily to become the ultimate survivors of once ruling life forms.
Crocodiles and alligators together with the closely related caimans and gharial, all belong to the order crocodylia, and are morphologically very similar. They have lizard-like shape, only much bigger in size, horny-plated protective covering and enormous, strong jaws lined by a number of vicious-looking, powerful teeth. The body size varies according to the species. The salt water crocodile of Australia is the biggest reptile in the world.
Collectively, they are known as crocodilians and all are found mostly in the warmer regions of the world or the tropics (of course there are a few exceptions).
HABIT AND HABITAT
The crocodilians tend to live near damp, freshwater swampy regions where there is a pond or a river or a canal. They mostly prefer estuaries or coastal fringes where tidal rivers meet the sea. They are said to be cold blooded, as opposed to their physiology. In terms of biology, they are poikilothermic.
Generally, they spend the night in the water and bask in the sun on the shores during the day. During the hottest times, they will either lie in the shade or slip back into the water to cool off. They are often seen lying on the shores gaping (mouth wide open). This helps them to get rid of the sweat just as a dog pants to evaporate water from the tongue surface, thus dissipating the body heat, lowering the body temperature in the process. This is also known as thermoregulation. Temperate species bask in the sun during the day to raise their body temperature and return to the water to cool off. They mostly hunt at night, leaving the daytime for basking in the sun. Those living in temperate regions, remain completely submerged except for their nostrils when the temperature is very low.
In certain classes of monkeys in India, there is a "Bir", i.e., a leader in their community that live in a certain area, who seems to be the dominant male. The leader fights away all the other males who try to dominate and keeps its position till death. Also any strong monkey that is born in the community in presence of a ruling "Bir" is killed so that it won't pose any threat to the leader when grown up. The crocodilians seem to have a similar nature. They live in large groups and are territorial with one dominant male. His job is to spend more time in upper levels of water while the others occupy the lower levels, combing his boundaries and chasing any large male who might be interested in his females making loud bellows. The dominant animals also choose nesting sites, food, basking sites, and living space. Combat to gain dominance is not uncommon.
All crocodilians make a variety of noises-grunts, hisses, low chirps and growls-which seem to convey messages to one another.
These crocodilians are strong swimmers with their powerful long tail propelling themselves and legs held against the body as they glide through the water in a back and forth locomotion. Sometimes they sport not to move and float motionlessly on the surface of the water as huge logs. There are times when the only visible parts of their body are the nostrils, ears and the eyes on top of their heads, while the rest remains submerged. Although they need to breathe at the surface, crocodilians can dive underwater and remain there for quite some time. During a dive, valves close over the ears and nostrils and a membrane protects the eyes. They can also leap almost vertically out of the water in pursuit of prey or to escape attack from an aggressive relative.
Crocodiles can remain submerged for a very long period for about an hour or two. It depends on the temperature. When the temperature is fairly low and they're relatively inactive, they can remain beneath the surface for a prolonged period. Tropical species may avoid the hot sun by remaining under water or mud during the day. This is possible mainly due to the fact that they have a very well developed four chambered heart. Their sophisticated circulatory system allows them to separate oxygenated blood from unoxygenated blood, quite unusual of the other reptiles. They can shut down blood flow to the non-essential organs keeping the vital organs active. Some crocodilians also estivate (sleep out the summer).
Once on land, locomotion is mainly carried out by their widespread webbed feet that are capable of galloping, when needed. They can also run by simply speeding up their walk. Their speed can outrun that of man's or sometimes even a horse. Nevertheless, they prefer to stalk slowly on their large, long bellies. Sometimes they move like lizards, moving one foot at a time.
Crocodilians are egg-laying creatures. In terms of biology, they fall in the oviparous group. During the breeding season (a wet season is chosen), they mate after fighting with other males in catching a female. The males of almost all the species mate with more than one female, a condition termed polygyny in biology. About a month after mating, the female crocodiles of some species will find a place on land to lay her 20-80 eggs while others make a nest of mud and vegetable debris which she collects and carries in her mouth. The important factor is to keep the eggs in a fairly constant temperature in a moist nest.
After incubation, almost all the tiny hatchlings emerge out at the same time breaking through the eggs with their tooth at the tip of the snout only to be carried away by their mother to the water where she releases them immediately. The young and miniature offspring have a great resemblance to their adults even at the time of birth.
Mating may take place in the water at different times of the year, according to the various species and where they live. The behaviour of the crocodilians after mating also varies according to the species.
For 18 months the hatchlings of the same brood remain in the same water body together under the constant vigil of their mother (and father in some species) who guards them from falling prey to otters, raccoons, herons, snapping turtles, large fish and water snakes. The baby crocodiles have differential growth rate depending on the species. At the age of three years, they become somewhat mature to wander away and travel distant lands establishing their own territory.
Crocodiles and alligators become sexually mature when they reach a certain length-between five to fifteen years old, according to the species. They continue to grow their entire lives, even after sexual maturity has been reached. They are extremely long living; some people claim they live to be 100 years old in the wild, although this has not been authenticated.
CROCODILES ARE AGGRESSIVE HUNTERS
The crocodiles have proved themselves to be extremely dangerous, cannibalistic and aggressive hunters. Some species have been observed to hunt cooperatively. They possess strong jaw muscles and sharp teeth to rip apart and for biting, tearing, grasping and holding prey. They watch and wait silently and stealthily, in the water or the water's edge, concealing themselselves, for their prey to come within range when they can startle them by a swift attack and pounce upon them. They have certain advantage to camouflage themselves, as they seem almost as fallen logs on the riverbanks due to their rugged skin texture. Small fish, crustaceans, crabs, insects, etc. are hapless victims to the younger generations. Adults attack and eat larger animals like turtles, fish, fox, pigs, birds, dogs and crabs, by overpowering them and dragging them down in the water holding by their sharp, specially designed teeth. They are all entirely carnivorous. Once it is caught within the jaws, it is swallowed whole. Larger victims are drowned down into the water, torn into pieces and swallowed. Their amazing digestive system is powerful enough to dissolve bones of their prey.
CROCODILES ARE RULING WHILE DINOSAURS ARE LONG DEAD: HOW?
Crocodilians, the direct descendants of the once prevalent archosaurs and the survivors of the dinosaur age (the age of reptiles), are known to be the most intelligent animal in the reptile kingdom in modern day world. While dinosaurs and almost all their contemporaries, once dominating life in all the continents and oceans, have disappeared in the pre-historic days, crocodilians survived miraculously as living fossils. Here are some facts that may shed light on as to how they managed to survive, undergoing only a very few changes, the adverse situations thus adapting themselves to the present day survival conditions. The fossilized remains show almost identical physiology as was present in the ones that dated back in the dinosaur period.
* It is known that crocodiles further evolved to certain terrestrial forms.
* They are extremely tough and robust with an incredible immune system that helps them to sustain severe injuries.
* They have a long life, spanning almost a decade.
* They learn quickly to avoid dangerous situations and adapt to changes in their situation.
* They can withstand bad, unhygienic, dark conditions with stinky dead matters all around.
* Their aquatic environment might have saved them from any disaster occurring on the land surface.
* They have an awesome capacity to deal with starvation. They can survive an entire year without food, yet remain active. So, if the demise of the dinosaurs was caused by an asteroid-winter type of scenario, then crocodiles may well have been able to survive that.
* There is some speculation that all the big dinosaurs were probably warm-blooded for which they needed to maintain their body temperature independently of the surrounding temperature. Thus, they had to eat all the time. Maintaining the body temperature consumed almost all the acquired energy. This, under drastic conditions, proved fatal as the dinosaurs failed to go through long periods of fasting. While, on the other hand, the crocodiles went on merrily in their low temperatures and dark conditions.
* They can tolerate cold temperature well. They normally become latent in cold weather and dig deep burrows into the banks of rivers and lakes and retire to them.
* The rate of hatching eggs is much higher in case of crocodilians than in other reptiles. Eighty or ninety percent of eggs laid hatch. Also there are a lesser number of enemies snatching away the eggs since they are very protective about them.
* Crocodilians are said to use energy in food more efficiently than almost any other animal. Food is stored as fat in the animals' tails, backs, and elsewhere in the body. Up to 60% of the food intake may be converted to fat. They utilize the food to convert them into tissue masses for their quick growth. This enables them to undergo long periods of fasting during unfavorable conditions.
* Their heavy, non-overlapping scales combined with hard bony plates on the skin surface act as Armour protecting the underlying skin.
* They are opportunistic hunters.
These living fossils have survived through innumerable odds since dating back to more than 200 million years. They have seen and passed through all the disasters that wiped away their giant relatives, the dinosaurs. But this was all before the evolution of man on earth. After that their life has constantly been under serious near-extinction threat in the wild. Should we not do something helpful for them to survive in their own environment and thus save nature's wealth than mutilate them for our mere pleasures? A layman might think "why?" - they are dangerous killers and aggressive carnivores. Killing them might help us save humans and livestock. It is true that they are the largest predators in their habitats and their conservation is challenging but certain facts might lead us to look into the matter from a different angle.
* The crocodilian family is facing extinction in man's hand. They are fascinating creatures, the most intelligent among the reptiles, which enrich our ecosystems. They have a right to exist on this planet as an integral part of its rich biodiversity.
* Alligator farms are popular tourist attractions. Certain farms in India conduct a successful breeding program that has ensured the survival of the mugger, gharial and saltwater crocodiles into the next century. They are planning a visitor center with a large underwater viewing area for the adult gharial and enclosures for other exotic reptiles.
* Through ages crocodiles have influenced many cultures in their own way that led to the development of myths and mythologies, art and literature, songs and stories and have made a place with Gods in some regions of the world. After death, in traditional burial ceremony in India, jewelry is thrown to the gharials in respect.
* These predators help control the spread of rodents and other animals in marshes and swamps. They clear out the dead remains of any animal.
* Alligators dig holes, with the help of their powerful jaws and claws to clear vegetation. These are filled with water in the rainy season thus providing water for the drier months. These small water bodies become the home of various animals like fishes, insects, turtles and birds.
* Rearing of crocodiles in farms or ranches means a constant source of skins and meat, which are considered so invaluable to man in the commercial sense. These are the safest methods to exploit their population with the minimum risk, yet maintain their species on the planet.
* Most crocodile farms conduct educational tours and shows for the public. This education promotes knowledge to understand crocodiles better and how to live in harmony or safety with them.