Gharial

## Description

Gharials (Gavialis gangeticus ) are one of the biggest crocodilians (a group that includes alligators, crocodiles, and caimans) and have the narrowest snout of these different species. Their common name is due to the bulbous nasal snout of adult males, which looks like an Indian pot with the name 'ghara'. The different physical appearance of males and females is unique to gharials amongst the crocodilians and accentuated by the male’s larger size. Furthermore, unlike other crocodilians, gharials have relatively weak legs, and a fully grown adult cannot raise their body off the ground.

## Appearance

The gharial is olive-colored, with adults being darker than young, which have dark brown cross bands and speckles. Its back turns almost black at 20 years of age, but its belly is yellowish-white. It has four transverse rows of two scales on the neck, which continue along the back. Scutes on the head, neck, and back form a single continuous plate composed of 21 to 22 transverse series, and four longitudinal series. Scutes on the back are bony, but softer and feebly keeled on the sides. The outer edges of the forearms, legs, and feet have crests jutting out; fingers and toes are partly webbed. Its snout is very long and narrow, widened at the end, and with 27 to 29 upper teeth and 25 or 26 lower teeth on each side. The front teeth are the largest. The first, second, and third lower jaw teeth fit into spaces in the upper jaw. The snout of adult gharials is 3.5 times longer than the width of the skull's base. Because of this long snout, the gharial is specially adapted to catching and eating fish. Male gharials develop a hollow bulbous nasal protuberance at the tip of the snout upon reaching reproductive maturity. This protuberance resembles an earthen pot known locally as "ghara". The male's ghara starts growing over the nostrils at an age of 11.5 years.

## Distribution

Gharials once thrived throughout all the Indian subcontinent’s major river systems, across the rivers in the north from Pakistan’s Indus River, across the floodplain of the Ganges to the Irrawaddy River of Myanmar. They are extinct today in the Indus River, the Brahmaputra of Bangladesh and Bhutan, and the Irrawaddy River, and they occupy only 2% of their earlier range. Gharials are found in the deep, calmer sections of fast-flowing rivers and migrate seasonally with the start of the monsoon.

## Behavior

Gharials are the most thoroughly aquatic crocodilians, and leave the water only for basking and building nests on moist sandbanks. They are diurnal and spend much of their day basking in the sun, especially in the winter. They like to revisit the same spot for this purpose, which is always near water. Gharials "gape" while they bask, in order to dissipate excess heat, usually done for 10-20 minutes at a time, while the head is at an angle of 20 degrees. On very hot days they submerge their bodies completely, leaving just their head above the water at an angle of 20-30 degrees. Gharials gather in groups for basking and nesting but are generally solitary. They use three main hunting strategies, one being the sit and wait for an approach where they float submerged almost completely and stay still until their prey passes by. The second is the sweeping search, which involves a sensory organ located on their scales that senses vibrations in the water as it slowly moves through the water. The third strategy is to strike rapidly. Gharials seem to communicate with vibrations in the water or buzzing sounds made by the males with their snouts.

## Diet

Gharials are carnivores (piscivores); they almost exclusively eat fish, although rarely they will eat carrion or water birds. Young gharials eat small frogs, insects, and larvae.

## Reproduction

Gharials are polygynous. A male will guard his territory, where several females live. It will use its "gharal" during courtship, the lid of cartilage on the male’s nostrils that flaps when he exhales, making a loud buzzing noise. The gharial is also used during territorial defense. Males also hiss and slap the surface of the water with their jaws. Underwater jaw slapping is used to attract possible mates as well. When a female locates a male, they rub their snouts against each other and the male follows the female around his territorial area. Mating generally occurs from November to February, which is during the dry season. Females dig a nest in a steep sandbank and lay 28-60 eggs in it, usually at night. Incubation lasts for 60-80 days, during which time females are very territorial when near their nest, but will tolerate other females using nests on the same beach. Hatchlings call out when they are ready to emerge, which alerts their mother to dig her eggs out from the nest. Gharials do not carry hatchlings in their jaws. Young remain with their mother for a period of several weeks or several months. They stay at nesting sites until monsoon floods arrive and return after the monsoon. Females are mature at 8 years old when they are 3 meters long, and males at 15 years old and 4 meters long. At this age, a male will grow a ghara on his snout.

## Population

### Population threats

Habitat degradation and loss pose the biggest threat to the gharial’s survival, as the explosion of the human population in the Indian subcontinent encroaches on the river systems that it lives in. Dams, sand mining, irrigation projects, and artificial embankments all have encroached on this species’ habitat, and its range has been reduced to only two percent of its former size. Furthermore, fishermen are in competition for the same food source and there are sometimes accidental or deliberate deaths. Eggs are used for medicinal purposes and adult males are killed for their snouts, which are thought to have aphrodisiac effects.

### Population number

According to the IUCN Red List, the total gharial population size is less than 235 individuals. This includes fewer than 200 individuals in India and fewer than 35 adults in Nepal. Overall, currently, gharials are classified as Critically Endangered (CR) and their numbers today are decreasing.

### Ecological niche

Being highly efficient predators, gharials are the top predators of fish in their watery environments.

## Fun Facts

Fishermen that live in the same area as gharials believe these animals can live up to 100 years old, although this has not been verified.

The eyes of gharials have a reflective layer called the tapetum lucidum behind them, which assists in night vision.

A gharial picks up low frequencies through its sense of hearing and is able to close its ear canal when submerged.

These are very intelligent animals, whose great memory helps them do very well to survive in the wild.

Gharials are one of the biggest crocodilians, but they have the narrowest snout of the crocodilian species.

The gharial’s distinctive narrow snout is a fine adaptation for the purpose of catching prey underwater, as it enables it to whip its head through the water sideways to snatch prey.

Gharial females that are very large are able to lay almost 100 eggs.