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Oh Crickey! Cold-blooded tales

Oh Crickey! Cold-blooded tales

Not too long ago, all the major river systems in the Indian subcontinent were occupied by a unique crocodilian suited specially for life in smooth, flowing rivers and preying on fish. Once distributed across Pakistan, India, Nepal, West Bengal and Myanmar, today these unique crocodilians have drastically declined to only 2 percent of their former range. The Gharial or the fish-eating crocodile – now the only survivor of the Family Gavialiade; Order Crocodilia – ranks among the world’s most magnificent and unusual reptiles.

 

What’s in a name?

The word ‘Gharial’ is derived from the Hindi word ‘Ghara’, which means ‘mud pot’, referring to the pot-like structure on the tip of the male Gharial’s snout. Actually, European naturalists read the word Gharial’ as ‘Gavial’ leading to its scientific name Gavialis gangeticus. It’s locally called as Gavial and Gharial and is often designated as the river guardian.

 

Rather imperial in appearance, Gharials have an elongated body and a long and laterally compressed tail– the male is 11ft to 15ft in length while the female is slightly smaller. The body is covered with dark or light olive coloured scales on the dorsal side whereas the ventral side is yellowish white.

Their streamlined body is built for prey. Gharials may seem slow on land, but in water, they’re surprisingly swift. The short forefeet and the hind feet have thick fingers that crenate with webs, which, combined with their webbed rear feet and the laterally flattened tail allow swift mobility in water. But on land, Gharials are far less nimble as they slide on their belly to push themselves forward. This is why they prefer to come on land just to bask.

But what truly characterises the Gharial is its long, narrow snout, which gradually gets thicker and shorter with age. The bulbous, cartilaginous knob on the male’s snout helps in creating a snorting hiss, which doubles up as a sign of dominance and also a courtship display. In fact, male Gharials are known to enter into combat for mating rights and to protect a harem of females. This striking sexual dimorphism occurs only in Gharials among all crocodile species.

 

Breeding

Breeding occurs mostly between November and January, and nesting then happens between March to May. Females build their nests themselves by burrowing the sand to make the egg chambers, where she deposits up to 60 eggs before covering it completely. The eggs weigh about six ounces, the largest among all crocodile species. After an incubation period of about 80 to 90 days, the hatchlings emerge. These young ones are cared for and looked after till the time they are in the nest. After that, they need to learn to reach the water by themselves, a sort of trial by fire to give them the practice to be able to survive in nature.

 

Gharial

Gharial females will dig an elaborate nest to carefully lay her eggs in and also guard their creche of babies as seen in this picture. Devoted mothers, Gharials leave no stone unturned to make sure her babies get a leg up on life. | Pic: Udayan Rao Pawar

 

 

Diet

A Gharial’s snout is adapted to its fish-eating characteristic. It ends in an extra-long, thin set of jaws studded with about 110 sharp teeth. Fish is an adult Gharial’s essential diet, which it alternates with crustaceans. Young ones feed on insects, frogs, tadpoles and small fish.

 

Temperature-dependent sex determination

Unlike in mammals and birds, where the determination of embryos sex is based on the combination of chromosomes, the sex of Gharial embryo is dependent on the temperature of its environment. Research shows that only when the temperatures in the nest are in a particular range, that embryos turn into males. At temperatures below or even above that range leads to the birth of females. Add climate change into this equation, and scientists fear that with temperature extremes getting more common, sex ratios in Gharials can be irreversibly skewed and hasten their population depletion.

 

Conservation status and threats

  • Though an apex predator of the aquatic environment, the Gharial population has drastically declined in recent years.
  • It is now listed as ‘Critically Endangered ’as per IUCN Red List of Threatened Species.
  • Habitat destruction, due to human interference is responsible. Sand mining, riverside agriculture, livestock grazing, construction of dams disrupt nesting sites.
  • Prey depletion is yet another reason for declining Gharial populations.
  • Over-harvesting of fishes by humans leaves less subsistence for this aquatic predator.
  • Gharials often get tangled in fishing nets and die due to drowning or starvation.
  • Locals are known to collect Gharial eggs, in effect eliminating an entire Gharial generation.
  • Pollution and siltation further worsen the situation.
  • Gharials usually die due to consumption of contaminated fish.
  • Gharials were largely hunted for trophies. Their skin is still in demand for accessories like wallets, belts, shoes and as ingredients in indigenous medicines.

 

Conservation

Arguably the most thoroughly aquatic of the existing species of crocodilians, these generally reside in flowing rivers with deep pools, high sandbanks and a good, healthy stock of fish. These exposed sandbanks are used for nesting and hence it’s the need of the hour to guard not just the river guardian but also its habitat against hazards. The Gharial is an indicator of the good health of its rivers. Rearing Gharials in captivity seems to be one of the more successful exercises in conservation. Captive breeding for restocking wild population has been implemented in the National Chambal Sanctuary in Uttar Pradesh, Chitwan National Park and also in the Madras Crocodile Bank.

 

Cover Pic: With specimens reaching almost 6m in length, the Gharial is one of the longest of all living crocodilians and is unique with its extremely long, thin jaws, which are an adaptation for a predominantly fish diet. | Pic: Ajit Huilgol

 

This article was first published in Saevus Magazine Sep-Oct 2013 Issue

Read also: Driving through fascinating Mudumalai 


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