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They are direct descendants of now extinct dinosaurs and thus are one of the oldest species on the earth.They live mainly in Africa, Australia and Asia,America.Crocodile have 23 species, the largest one is Saltwater Crocodile and smallest one is Dwarf Crocodile.crocodiles are known to live for 50 to 60 years though it may be hundred of years.They are the world's largest living reptiles.They are named as "living fossils"because of the fact that Crocodilians appeared on earth about 240 million years ago, but their structure has remained more or less unchanged.Many local populations are threatened, yet no crocodilian species has been driven to extinction.
Crocodiles are found in a variety of wetlands.The salty inhabits the coastal flood plains, the freshy water species inhabits tanks, lakes and rivers.The freshwater crocodile or the mugger is found in India,Pakistan and Sri Lanka,where it occurs in the numerous man-made lakes or tanks in the low country dry one. It is estimated that there could be at least 1,500 freshwater crocodiles and perhaps no more than 300 estuarine crocodiles in Sri Lanka. In the United States, the crocodile is found only in South Florida.They were placed on the endangered list but now after sincere efforts,the American crocodile goes off the federal endangered species list.Habitat protection is the key to survival.
Crocodiles are carnivores;sirviving on fish, birds, turtles, frogs, and mammals. Young crocodiles eat worms, small fish, and insects.Crocs hunt during night, with the eyes, ears, nostrils and the cranial platform are above water.They wait half-submerged for land-bound prey such as spotted deer, wild boar, or even a buffalo calf which come there to quench their thirst.Due to the presence of special sensory organs,crocs can detect smallest movement in water..Crocs are among the few reptiles that have a voice.They have also good eyesight and their vision is greatly enhanced by a layer of guanine crystals behind the retina, known as the retinal tapetum. Despite its size, a croc cannot eat larger prey due to small stomach. Interestingly,Crocodiles are much more closely related to birds and dinosaurs than the other reptiles.The sex of a crocodile is determined on the basis of its temperature. At time, a female crocodile helps the eggs hatch, by gently cracking the shells in her mouth.
Crocodiles are polygynous, meaning single male mating with a number of females. Temperature or rainfall providesstimulus for ovulationdepending upon their habitats. Mating takes place in water and is preceded by courtship.Sex is of the offspring is determined by temperature. Low temperatures (300C or less) mean slow development, leading to the production of females, while high temperatures (320C or 330C) produce mostly males. The young crocs produce a cheeping sound to alert the mother who would come to excavate the nests and carry the newly hatched young in her mouth to water as the hatchig time reaches. Out of every 1000 eggs that hatch, only 8 crocs survive up to 5 years of age Maternal behaviour includes nest defence, nest opening, manipulation of eggs to release hatchlings, and mouth transport of eggs and the young.Being reptiles, crocodiles cannot maintain a constant internal body temperature through physiological means. since their body temperature is determined by the outside heat source available. Crocs prefer a temperature range of 30-330C. To remain within this range, they would often move in and out of water. In hot weather, they would bask by orienting themselves in such a way that the maximum body is exposed to the sun. Once the body is heated, crocs would face the sun and open their mouths to allow the brain to cool through evaporative heat loss of the blood.
Commonly known as "Mugger", this species is found in freshwater lakes, ponds, marshes, reservoirs, irrigation canals,man-made ponds, and even recently in coastal saltwater lagoons.They are fair sized crocodiles, reaching maximum length of 16 ft. and having an average length of 13 ft. The males are generally larger than the females. Mugger crocodiles have life spans of 40+ years. They are highly social and communicate with a wide variety of vocalizations. Adults have grey to brown body.They are excellent swimmers, using their flat tail to propel them. The body is well protected by a tough, scaly skin. The juveniles feed on invertebrates insects, and small vertebrates. Adults eat larger prey, such as fish, frogs, snakes, turtles, birds, and mammals Their social behavior include communication, gregarious behavior, dominance interactions, and territorial activities.One month after the mating, the eggs are deposited by the female into the nesting hole . This takes place between February - April .The mugger is found primarily on the Indian subcontinent and extends into Pakistan and Sri Lanka.
Saltwater Crocodile has a high tolerance for salinity, being found in brackish water around coastal areas and in rivers. However, it is also present in freshwater rivers, the estuarine crocodile is restricted in its distribution to the tidal estuaries, marine swamps, coastal brackish water lakes and lower reaches of the larger rivers.The saltwater crocodile has a vast geographical range that extends from Cochin on the west coast of India to the Sunderbans in West Bengal and to the Andaman Islands. These crocodiles are meat eaters.They eat snakes, buffaloes, domestic cattle, and pretty much anything else it can get.
Interestingly breeding ttakes placed in freshwater areas. 40 to 60 eggs are usually laid after mating. The female digs the young out of the nest when they start their characteristic chirping sounds.
In India, they are found within the river systems of the Brahmaputra, the Ganges, They usually leave the water only to bask and nest, both of which usually occur on sand banks.
The gharial is one of the largest of all crocodilian species.Adults are primarily fish eaters, for which their jaws and teeth are perfectly adapted teeth are ideally suited for holding struggling prey such as slippery fish. Some of the larger gharials can take larger prey, including mammals.The mating period occurs for two months during November, December and into January. Between 30 and 50 eggs eggs are laid by female.The gharial is considered to be one of the most critically threatened of all crocodilians.
Nile crocodile as the name suggests found in Africa. Nile crocodiles occur mostly in coastal lagoons, estuaries and in the rivers bordering the equatorial forest belt. In East Africa, they are found.The Nile crocodile is the largest crocodilian in Africa and is sometimes regarded as the second largest crocodilian after the Saltwater crocodile.Nile crocodile is an opportunistic predator killing any animal that is within striking range. They start life very small. Adult, Crocodile's diet is fish and other small vertebrates. can potentially eat nearly any animal that comes to take a drink at the edge of the water.The most frequently recorded mammalian prey taken by Nile crocodiles are waterbuck, wildebeest, zebra, , goats, sheep and cattle.The African Big Cats have occasionally been observed preying on crocodiles.
During the mating season, males attract females by bellowing, slapping their snouts in the water, blowing water out of their noses, and making a variety of other noises, though they are much less vocal than American alligators.The larger males of a population tend to be more successful.Nesting is in November or December, which is the dry season in the north of Africa, and the rainy season in the south.Nile crocodiles have Temperature-dependent sex determination which means the sex of their hatchlings is determined not by genetics, but by the average temperature during the middle third of their incubation period.There are an estimated 250,000 to 500,000 individuals in the wild.
CONSERVATION OF CROCODILES
Habitat protection is believed to be the main factor that for long term survival of these living fossils.Crocodiles have declined both in range and number since they were indiscriminately hunted in the past for skin and meat.Intensive fishing has also led to the decline of freshwater crocs in some areas.Reclamation of swamps, draining of coastal wetlands, conversion of mangroves to prawn farms, and the removal of riverine forests are some of the threats faced by these species.Conservation of crocodiles is firstly important as they check the population of fish to sustainable levels,secondly the crocs are significant part of the ecosystem whose health is important for the survival of the human beings and lastly this is our duty to protect the living fosssils so that our future generations can see these mighty creatures.
Crocodile Conservation in India was started in 1975 due to the rise in the death rate of crocodiles.Concerned at the dwindling crocodile populations the Madhya Pradesh government undertook a programme for the gharial under the Crocodile Project. Important crocodilian habitats were identified and given protection. Three sanctuaries were specially created as part of the programme (1) National Chambal Sanctuary; (2) Ken Gharial Sanctuary; and (3) Son Gharial anctuary. The main focus of management in these protected areas was to provide protection to crocodiles,but the whole ecosystem gets protected in the process.(Rao, et. al. 1995).Conservation efforts are going on in Cambodia, Myanmar, Laos, the Philippines, Thailand, China, and Vietnam.
Crocodile Conservation in India has taken different forms, from starting a Crocodile Bank in Chennai to conserving and protecting the natural habitat of the crocodiles. The Crocodile Bank in Chennai houses seven different species of crocodiles.The bank has produced 6000 crocodiles already.