Gharial (Gavialis gangeticus)

Gharial, view from behind

(http://www.arkive.org/gharial/gavialis-gangeticus/image-G113436.html)

  • Name: Gharial
  • Latin: Gavialis gangeticus
  • Classification: Reptile
  • Origin: India
  • Lifespan: 50-60 years

Taxonomy

  • Kingdom: Animalia (animals)
  • Phylum: Chordata (vertebrates)
  • Class: Reptilia (reptiles)
  • Order: Crocodilia (crocodiles)
  • Family: Gaviadlidae (gharial)
  • Genus: Gavialis (gharial)
  • Species: Gavialis gangeticus (gharial)

Apperance

  • Length: (Female) 2.5-4 meters, (Male) 3-6 meters
  • Weight: 150-250kg

Gharials are long and slender animals. Their colouring is light olive tan with dark blotches or bands running down their body and tail. Their webbed feet and strong tail make it an excellent swimmer; however their limbs are weak, keeping them from making extensive overland journeys that their fellow crocodilians make. Gharials are the largest of crocodiles.

The males have a large, bulbous mass on the end of their snout known as the ghara. This is the Indian word for ‘pot’. The function of the ghara is unknown but it is thought to produce a loud buzzing noise when it vocalizes.

The eyes are set high on its head and its jaws are equipped with sharp, pointed teeth that point forward and slightly outward. They have 54 teeth on its upper jaw and 48 on the lower. They have a tough hide which is sought after by hunters and poachers. Their legs are proportionally longer than other crocodiles but they are clumsy on land. Their leg musculature doesn’t allow them to raise their body or tail off the ground. However, they can belly-slide quite quickly.

Relatives

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  • Saltwater crocodile (Crocodylus porosus) -LEAST CONCERN-
  • Cuban crocodile (Crocodylus rhombifer) -CRITICALLY ENDANGERED-
  • Dwarf crocodile (Osteolaemus tetraspis) -VULNERABLE-
  • Orinoco crocodile (Crocodylus intermedius) -CRITICALLY ENDANGERED-

Habitat & Distribution

Gharials are adapted to live in riverines, in the calmer areas of the deep, fast flowing rivers. Their physical attributes do not make it good for moving about on land. In fact, the only reason it leaves the water at all is to bask in the sunlight and to nest in the sandbanks of the river.

In India, the Gharial can be found living at the National Chambal Sanctuary, the Katarniaghat Wildlife Sanctuary, the Son River Sanctuary and the Satkosia Gorge Sanctuary. In Nepal, they live at the Chiwan National Park and the Bardia National Park.

Due to poaching, they are now extinct in the Indus River of Pakistan, the Brahmaputra or Bhutan and Bangladesh and the Irrawaddy River of Myanmar.

(http://www.theanimalfiles.com/reptiles/crocodiles_alligators/gharial.html)

Diet

The diet of the Gharial changes as it grows from a juvenile to an adult. The juveniles eat a variety of invertebrate prey such as insects, plus smaller vertebrates such as frog, but primarily they eat small fish.

The adults are fish eaters, for which their jaws and teeth are perfectly adapted. The thin, narrow shape of the snout gives it low resistance in the water. Also, their teeth are perfectly suited to keeping grip on struggling prey, such as slippery fish.

Behaviour

Like most crocodiles, Gharials get along well with each other and like to live in groups. They stay in the water most of the time, occasionally coming out to bask in the shore. At the slightest sign of threat, they will dive back into the safety of the water. On especially warm days, the Gharial will open its mouth wide to cool off. This serves the same purpose as panting does for a dog.

The mating season for the Gharial arrives in December and January. During this time the adult males begin fighting each other to set up territories in the shallow water. Two males will lie side by side, life their heads up out of the water and being pushing each other with their snouts. The winner is the one who can topple the other over. Sometimes, the fights can become more violent, where the males being to bite each other.

A male with a good sized territory can attract several females to mate with. The ghara is also important during mating season. It produces a loud buzz which is attractive to females and warns other males to stay away.

Reproduction

A female gharial will lay her eggs sometime between March and May. They dig their nests in the dry ground on the bank of the river at least 5ft (1.5m) above water level. Females are very fussy about the location of their nests and will change their minds several times, even after they have begun to dig. They are territorial over their nests and stay near most times, defending from predators if necessary, however, they will share beaches will other females.

After digging a hole in the sand, the female will lay her eggs inside and carefully cover them. The smallest females lay as few as a dozen eggs and many first-time mothers lay eggs that never hatch at all. The largest females will lay almost 100 eggs.

A typical gharial egg is 2.2inches (5.5cm) wide, 2.4inches (8.6cm) long and weighs 5.5ounces (156g). The eggs will hatch around 53-92 days after being lain. Eggs in the warmest nests usually tend to hatch sooner than eggs in cooler ones. The temperature of the nest also affects the gender of the young. Warm nests produce more males, and cool nests produce more females.
After the babies have hatched the mother will help them out of the nest and then she, and even possibly the father, will watch over them. However, many of the females young do not survive, despite this care. The eggs are often eaten by animals such as pigs, hyenas, monitor lizards and even by humans, and the babies are hunted after by birds and turtles. Also, the young are born during the monsoon season and can drown in floods.

Females can be ready to mate when they are at least 8 years old and are 10ft (3m) long. Males however must wait till they are 15 years old and about 11.5ft (3.5m) long until they can mate.

Adaptations

  • The gharial’s jaw is long and slender with interlocking teeth. This provides speed and grip for catching slippery fish.
  • The gharial’s tail is flattened on the sides. This helps the gharial to be quick underwater.
  • The eyes and nostrils of the gharial are positioned high on the head. This means that it can stay completely submerged underwater whilst being able to see and breathe.
  • The male gharial has a growth on the end of his nose known as a bulbous. This organ makes a low rumbling noise which is thought of as a way of attracting females.

Threats

Agriculture: In India, riverbanks are being taken over for agricultural use. This is limiting the nesting and basking areas of gharials.

Sand mining: Sand extraction is allowed outside of protected areas, but continues along the riverbanks of the National Chambal Sanctuary. This destroys areas required by the gharials for nesting and basking.

Livestock grazing: Cattle, water buffalo and goats graze along the riverbanks of gharial habitat areas which cause destruction to gharial nests.

Disturbance: Gharials are shy and wary creatures. So human activity and livestock grazing will cause disturbance to the natural gharial activity of nesting and basking, and drive them from their habitats.

Pollution and Siltation: Polluted Rivers damage the fish stocks that the gharials depend upon, as well as threatening the other species of animals and plants within the river ecosystem.
Dams, barraged and irrigation projects: These man-made dams change the courses and water levels of the rivers. In some areas, it drastically lowers the river level and makes former habitats inhospitable for gharials. In other areas, it makes the water level so high that the rivers flood and washes gharials away from protected areas. This is thought to be a significant source of mortality in hatching gharials.

Fishing and Turtle Poaching: Gharials are often caught in fishing nets. Their snouts can become entangled in the nets, and then drown as they can’t resurface to breathe. Sometimes a trapped gharial can break free but the nets remain tangled around their snouts and the gharial will starve to death. Often, when gharials are found entangled in fishing nets their heads or snouts are cut off by fishermen. A gharial can survive for many months without a snout but will eventually die of starvation.

Conservation

  • IUCN Status: Critically endangered

The most successful group dedicated to helping the gharial numbers increase is the Gharial Conservation Alliance (GCA). They carry out a number of different activities including scientific population surveys, captive, breeding, wild restocking programmes and education, awareness and government lobbying. All created to help the numbers of gharials increase and to protect existing ones.

In 1975, Project Crocodile was set up with the Indian Government and the United Nations Development Programme Food and Agriculture Organization (UNDP-FAO). 240km of habitat was set aside in 6 gharial sanctuaries, and 16 rearing centres were set up for ‘head-starting’ programmes.

In 1975-1992, 5,000 head-started gharial release.

Fun Facts

  • Male: Male Crocodile
  • Female: Female Crocodile
  • Young: Hatchling, Irwin
  • Group: Float, Bask, Congregation, Nest
  • The gharial is the longest crocodilian species.
  • The snout becomes longer and thinner as the gharial gets older.
  • They have 54-58 teeth on the upper jaw and 50-52 on the lower jaw.
  • Humans are the main predator of the gharials.
  • Gharials are also known as Gavial, Indian Gharial, Indian Gavial, Fish-eating crocodile and Long-nosed crocodile.
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