Gharial (Gavalis gangeticus)

Night Safari Ranger Station

General Information
Habitat
Feeding and Breeding
Conservation
Interesting Facts
Bibliography

General Information

Characteristic elongate, narrow snout, similar only to the false gharial. Variation in snout shape occurs with age (generally becomes proportionally longer and thinner with increasing age).

The bulbous growth on the tip of the male's snout is called a "Ghara" (after the Indian word meaning 'pot'), present in mature individuals.

The elongated jaws are lined with many interlocking, razor-sharp teeth - an adaptation to the diet (primarily fish in adults). Gharials (the more aquatic of all crocodilians) are awkward out of the water mainly due to their short stumpy legs.

It is poorly equipped for locomotion on land - its leg musculature is not suited to raise the body off the ground (to produce the 'high-walk' gait) and is only able to push its body forward across the ground ('belly-sliding'), although it can do this with some speed when required.

It is however, very agile in the water - the tail is well developed and laterally flattened, and the rear feet possess extensive webbing.

The Gharial is uniformly dark olive-gray with a pale yellow belly. Juveniles have dark spots and crossbands against a light background.

 

Habitat

Found in Northern Indian subcontinent, Bangladesh (close to being extirpated), Bhutan (possibly extirpated), India, Myanmar (possibly extirpated), Nepal, Pakistan (close to being extirpated).

They are found within the river systems of the Barhmaputra (Bhutan and India), the Indus (Pakistan), the Ganges (India & Nepal) and the Mahanadi (India) with small populations in the Kaladan and the Irrawaddy in Burma. Riverine - more adapted to an aquatic lifestyle in the calmer areas of deep fast-moving rivers.

The gharial is poorly equipped for locomotion on land. It usually only leaves the water to bask and nest, both of which usually occur on sandbanks.

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Feeding and Breeding

The diet changes between juvenile and adult - the juveniles are well suited to deal with a variety of invertebrate prey such as insects, plus smaller vertebrates such as frogs.

Adults however, are primarily fish-eaters, for which their jaws and teeth are perfectly adapted - the thin shape gives the snout low resistance in water, which is suited to fast lateral snatching movements underwater; teeth are ideally suited for holding struggling prey such as slippery fish).

Some of the larger gharials are more opportunistic and take larger prey, including mammals. Although poorly-equipped to devour a human, such ability has nevertheless been endowed upon the gharial and indeed most crocodilians.

Human remains and jewelry have been found in their stomachs and were thought to validate this fear, but these are most likely to have been scavenged from the dead - the Hindi funeral ritual ends with the remains of the cremated body being sent down the river.

Jewellery is possibly ingested in the same way that stones would be in order to be used as gastroliths - hard objects which aid in digestion and to add weight to alter buoyancy.

Their stomaches are the most acidic recorded for any vertebrate, allowing them to digest even the bones and shells of prey animals. Their digestion is also aided by a muscular gizzard containing stones to help break down food.

Breeding
Females reach sexual maturity around 3 m in length (usually over 10 years old). Males guard a harem of 4 to 6 females to one male. The mating period occurs for two months during November, December and into January.

Nesting occurs in March, April and May (the dry season) where flask-shaped holes are dug on sandbanks above the flood level. Between 30 to 50 eggs (average of 37) are deposited into the hole before it is covered over carefully.

The eggs are about 8-9 cm long, with hard calcified shells. The size of the eggs in gharials is the largest for any crocodilian species, weighing an average 160 gm.

After 83-94 days, the juveniles emerge (about 40 cm long), although the female has not been observed assisting the hatchlings to the water as in other crocodilian species. This is perhaps because of the unsuitability of their jaws for carrying hatchlings, and also because of their needle-sharp teeth.

However, protection of the young does occur around the nesting area for some time after hatching. Two of the main predators that will eat the juveniles are the eagle and the Komodo dragon.

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Conservation

The gharial is considered to be one of the most critically threatened of all crocodilians, becoming alarmingly close to extinction in the 1970s.

Fortunately, there has been some recovery through conservation programs, and a reasonable amount of hope lies with the conservation and management programs, which are now in place.

Full protection was granted in the 1970s in the hope of reducing poaching losses, although these measures were slow to be implemented at first. Now there are 9 protected areas for this species in India, which are linked to both captive breeding and ÔranchingÕ, operations where eggs collected from the wild are raised in captivity (to reduce mortality due to natural predators) and then released back into the wild (the first being released in 1981).

Over 3,000 animals have been released through these programs and the wild population in India is estimated at around 1,500 animals - with perhaps between one and two hundred animals in the remainder of its range.

The major threat at present is habitat loss due to human encroachment, and disruption of populations through fishing and hunting activities. A lack of suitable release sites has also started to become a problem for the management of the gharial.

Eggs are collected for medicinal purposes, and males are still hunted for the aphrodisiac properties associated with the snout. They may also be snared in fishing nets and killed by fishermen. The decline in gharial populations have been linked to a decline in fish catches, as predatory fish (of no interest to the fishermen) form a major part of the gharialsÕ diet.

Plans for the future include surveys of areas such as Pakistan and Burma where the status of the gharial in the wild is unknown.

CITES : Appendix I
Revised IUCN Classification : Endangered. Population < 2,500 and severely fragmented

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Interesting Facts

How does the crocodile breathe and feed in the water?
A crocodileÕs mouth is not watertight when closed and water easily enters when the crocodile submerges. The palatal valve seals the opening to the throat, preventing water from entering when the crocodile is submerged. When taking an aquatic prey, the crocodile can open its mouth without flooding its throat. Terrestrial prey can also be dragged into the water and drowned.

The internal nares (where the nostrils open internally) move right to the back of the upper palate when the crocodile is partially submerged. Therefore as long as the nostrils are open and above the water, the crocodile can effectively by-pass the palatal valve and breathe.

When the crocodileÕs head is totally submerged, however, the nostrils are sealed to prevent influx of water. In order for the crocodile to eat, it must either leave the or water or hold its head at an angle.

In order to swallow on land, the crocodile tips its head back and throws the food towards the back of its mouth with a flick of the head. Muscles pull the palatal valve down towards the tongue, allowing the food to enter the throat and oesphagus. In this position, the prey can be manipulated by the jaws and crushed with assistance from the teeth.

How long can a crocodile stay under water ?
They can submerge and remain underwater for a variety of reasons. In most voluntary dives, they can stay underwater for between 10 to 15 minutes. If the crocodile is trying to hide from a threat, dive length may be longer, up to 30 minutes or more.

How fast do crocodiles grow?
The 20-26 cm hatchlings may grow 5-30 cm per year, depending on the species. Females may take 8 to 14 years and males 10 to 17 years to mature.

Do crocodiles cry Ôcrocodile tearsÕ ?
Crocodiles do produce tears (like ours) which are products of the lachrymal glands. These glands produce a fluid which helps to clean the eye, lubricate the passage of the nictitating membrane across the eye's surface and probably also helps to reduce bacterial growth.

Tears are normally only noticeable if the crocodile has been out of the Water for a long time and the eyes begin to dry out. Though they do produce tears, they do not actually cry - that is a myth.

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Bibliography

Honolulu Zoo
St. Augustine Alligator Farm
IWC Species Page

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