GHARIALS: CHARACTERISTICS, BEHAVIOR, REPRODUCTION, CONSERVATION

GHARIALS

gharial female

Gharials (Gavialis gangeticus) are one the rarest and most unusual-looking crocodilians and the most aquatic. Also known as gavials and fish-eating crocodiles, they are four to seven meters (13 to 23 feet) in length and spend most of their time in the water. Compared to other crocodiles, their legs are relatively weak and their feet are broadly webbed. This because these reptiles spend their time chasing after fish rather than lunging for prey at the shore like many crocodile species do. There are a few hundred and possibly a few thousand of them in India and Nepal. Before they used to also be found in Arabia, Bangladesh, Bhutan, Burma, and Pakistan.

Gharials historically inhabited four river systems: the Indus (Pakistan), the Ganges (India and Nepal), the Mahanadi (India) and the Brahmaputra (Bangladesh, India, and Bhutan); it also may have occurred in the Irrawaddy River in Myanmar.[Source: Kyle Bouchard, Animal Diversity Web (ADW) /=]

Gharials in India prefer clear freshwater rivers with fast flowing currents. They congregate at river bends and other sections of rivers where the water is deep and the current is reduced. Because Indian gharials are not well adapted for moving around on land, they leave the water rarely, usually only to bask and to nest. They prefer sandbars in the middle of the rivers for both of these activities. Juveniles may seek out quiet backwaters or smaller streams.

Gharials are not to be confused with false gharials (Tomistoma schlegeli), which look similar and live in Southeast Asia. A 2018 study found that false gharials are gharials’ closest living relative. The most obvious difference between the two species is color: False gharials are red-brown with dark spots; gharials are green-gray and darken with age. They also live in different places. False gharials live in Malaysia and Indonesia; gharials live in Bangladesh, Nepal and India. [Source: Sascha Bos, HowStuffWorks, January 18, 2024]

Even though their teeth look scary gharials are probably harmless to humans. Some people believe they attack and eat humans, but this appears to be an unfounded fear. Gharials are generally not aggressive and have narrow jaws and thin teeth that are unsuited to attacking humans or large animals. The fear that gharials are man-eaters seems to come from the discovery of human remains and possessions in the stomachs of gharials. Some of the rivers gharials live are used in Hindu funeral in which cremated human remains are placed in rivers. Gharials may eat these remains. It is also a common practice for many crocodilians to ingest rocks (gastroliths) to aid in digestion and alter their buoyancy. Perhaps some human remains and jewelry are ingested for this reason.[Source: Kyle Bouchard, Animal Diversity Web (ADW) /=]

Gharial Characteristics

gharial range

Gharials are one of the largest crocodilians in the world. They generally range in weight from 159 to 181 kilograms (350 to 400 pounds) and range in length from four to 6.5 meters (13 to 21.3 feet). They are cold blooded (ectothermic, use heat from the environment and adapt their behavior to regulate body temperature) and heterothermic (having a body temperature that fluctuates with the surrounding environment). Sexual Dimorphism (differences between males and females) is present: Males are larger than females. Males and females have different shapes. Ornamentation is different. Males are typically five and six meters long while females are closer to four meters. [Source: Kyle Bouchard, Animal Diversity Web (ADW) /=]

Adult males can reach a weight of up to 600 kilograms (1,300 pounds). The heaviest recorded male weighed 977 kilograms (2,154 pounds). A 6.55 meter (21 feet 6 inch) -long gharial was claimed to have been killed in the Ghaghara River in Faizabad in August 1920, but no reliable measurements were taken. [Source: Wikipedia]

Gharials have large eyes and extremely sharp teeth (See Feeding Below). Their snout shape changes throughout an individual’s lifetime, usually becoming longer and thinner as the crocodile gets older. Males have a strange stiff hollow knob on their snouts called a "ghara" used in both visual and acoustic mating displays. The nostrils are closed with penislike erectile tissue that seals off the airways , when the animal is aroused and helps males produce bubbles during mating and loud buzzing noises. (See Mating Below).

Gharials have extensively webbed feet that give them a lot of thrust and maneuverability in the water. Movement on land is awkward. Their leg muscles are not strong enough to lift them off the ground, but they can push themselves along while sliding on the belly. The scales of gharials are smooth, which is different from most crocodiles and alligators. Adults are dark brown to greenish brown backs and yellowish white to white bellies Young Indian gharials have dark bands on the body and tail that usually fade when they become adults.

The only firm documentation of the lifespan of gharial is of a captive individual at the London Zoo, which was estimated to live to be 29 years old. Because of their large size, it is thought that they have a long life span. Fisherman that live near gharials believe that they can live as long as 100 years old, though this has not been confirmed./=\

Gharial Food and Hunting Methods

Gharials have between 106 and 110 razor sharp teeth (five pre-maxillary, 23 to 24 maxillary, and 25 to 26 mandibular teeth). Their long. slender snout, which is designed for catching fish, makes them looks like a scaly pole with teeth. Although the snout is so slender it looks as if it might be easy to break it is in fact quite strong. Gharials catch fish sideways and then flick them into the air and catch them headfirst so the crocodile can swallow the fish with the fish’s gills snagging in their gullet. Gharials eat only fish and require a specialized habitat of swiftly flowing rivers with sandy banks.

gharial eating a fish

Gharials are primarily piscivores (eat fish) but are also recognized as carnivores (eat meat or animal parts) and insectivores (eat insects), eats non-insect arthropods. Animal foods include fish, amphibians and reptiles. The diet of juvenile gharials is different from adults. Juveniles eat small animals, such as insects, crustaceans, and frogs. But as they grow older and their snout becomes thinner and longer, they eat almost exclusively fish.

There are three main hunting strategies employed bu gharials: 1) The sit-and-wait-approach is where they float almost completely submerged under water and remain motionless until their pray passes right by them. 2) The sweeping search involves an integumentary sensory organ found on the scales to sense vibrations in the water while slowly feeling through the water for prey. 3) The third hunting strategy is a rapid strike. The thin jaw creates low water resistance for quick snaps underwater.

Gharial Behavior

Gharials are solitary, natatorial (equipped for swimming), diurnal (active during the daytime), crepuscular (active at dawn and dusk), motile (move around as opposed to being stationary), sedentary (remain in the same area) and territorial (defend an area within the home range). They communicate with vision, sound and vibrations and sense using vision, touch, sound and vibrations. [Source:Kyle Bouchard, Animal Diversity Web (ADW) /=]

Gharails inhabit slow-moving backwaters of large rivers; leaving the water only to bask on a sand or mud bank or to lay eggs. When threatened they submerge themselves in deep water. Their legs are so poorly developed they have a hard time moving on land. Instead of properly walking they push themselves forward like a paddling surfboarder.

Kyle Bouchard wrote in Animal Diversity Web: Gharials spend a lot of time basking in the sun, more so in the winter than in the summer. They tend to revisit the same basking spot, which is always close to the water. Indian gharials also "gape" during basking to dissipate excess heat. Gaping is usually done in 10 to 20 minute intervals with the head at a 20 degree angle. On very hot days gharials completely submerge their bodies, leaving only their heads out of the water at a 20 to 30 degree angle. Indian gharials aggreggate in basking and nesting areas but are generally solitary. Nests are defended by females.

Like all crocodilians, Indian gharials possess integumentary sense organs. These are tiny pits in the scales that cover the body. These pits are able to pick up vibrations or changes in water pressure, which aid in the search for prey. Their eyes have a reflective layer behind the eye, the tapetum lucidum, which aids in night vision. A clear membrane, the nictitating membrane, protects the eye while under water. Indian gharials pick up low frequencies through hearing and are able to close the ear canal when submerged. Indian gharials apparently communicate via vibrations in the water and buzzing sounds made by males with the ghara on their snouts. /=\

Gharial Reproduction and Nesting

ghara on the end of the male gharial's snout

Gharials are oviparous, meaning that young are hatched from eggs, and engage in seasonal breeding once per year. Mating season varies regionally, but generally occurs between November and February, during the dry season, and egg-laying occurs between March and May. The number of eggs ranges from 12 to 100, with the average number of offspring being 35 to 60. Incubation lasts between 60 and 80 days. Independence occurs around three weeks on average. On average females reach sexual or reproductive maturity at eight years old, when they are three meters in length. For males, sexual maturity is attained at 15 years of age and four meters in length. At this time males grow a ghara on their snout. [Source: Kyle Bouchard, Animal Diversity Web (ADW) /=]

Fertilization is internal. Females lay shelled eggs in nests dug into sandy riverbanks and guard the nests during the incubation period. Sex is determined by egg temperature during the early to middle part of the incubation period. Very large females are capable of laying almost 100 eggs. Nesting occurs during the late dry season, from March through May. Females locate a steep sand bank where they dig a nest. During this time, they might dig a number of holes before finding the right spot. Holes are about 50 centimeters deep and from three to five meters from the water. Females lay eggs in the hole, usually at night.

Gharial Mating

Gharials are polygynous (males have more than one female as a mate at one time). Mating season occurs for about two months each year during which time male gharials become strongly territorial and assemble a harem of females. Mating takes place in the water. During the breeding season dominant male gharials become strongly territorial and assemble a harem of females. [Source: Kyle Bouchard, Animal Diversity Web (ADW) /=]

Males have a strange stiff hollow knob on their snouts — the ghara — used in both visual and acoustic mating displays and during territorial during defense. The "ghara" — the source of the gharial’s name — is a cartilaginous lid on the nostril. When the male gharial is aroused the nostrils close with penislike erectile tissue that seals off the airways and flaps when air is exhaled through it producing a loud buzzing noise. "Ghara" is the Hindi word for "mud pot," according to National Geographic.

During matting male gharials also hiss, and perform above water jaw slapping. While underwater, jaw slapping is also performed to attract possible mates. When a female finds a male, the two gharials rub each other with their snouts and the male follows the female around his territory. The female shows her readiness to mate by raising her head upwards, at which time the male climbs on top of her. The two then submerge for up to 30 minutes during copulation. /=\

Gharial Offspring and Parenting

gharial papa with offspring on its back; award-winning photo by Dhiritiman Mukherjee

Most of the parental work is done by females but sometimes males lend a hand. Females create a nest far away from the water edge and lat 50 eggs which at 150 grams each are unusually large for crocodiles. The females protects her young but does not carry them to the water, perhaps because of the shape of their mouths.

Kyle Bouchard wrote in Animal Diversity Web: An average Indian gharial egg is 5.5 centimeters wide, 8.6 centimeters long, and weighs 100 to 156 grams. During incubation females visit and guard eggs during the night but remain in the water during the day. During incubation females are very territorial near the nest, but they tolerate other females nesting on the same beach. Nests in warmer climates usually hatch earlier. Young are about 18 centimeters in length. The female (and perhaps the male) help excavate the nest during hatching.[Source: Kyle Bouchard, Animal Diversity Web (ADW) /=]

Females must provision eggs with yolk prior to oviposition, excavate a nest cavity, and guard nests. Females may uncover and assist young during the hatching process. After hatching, females protect hatchlings for several weeks, often until monsoon rains come, during which high water levels may disperse the young. The male will be tolerated nearby, but they do not actively protect hatchlings, though young will sometimes rest on the back of the male. /=\

A much celebrated photograph, taken by India-based photographer Dhritiman Mukherjee in 2020, shows a male gharial swimming in northern India's National Chambal Sanctuary, with with as more than 100 of his month-old offspring — from seven or eight different females — holding on to his back for safe passage. "Other crocs carry their young about in their mouths," Patrick Campbell, the senior curator of reptiles at London's Natural History Museum, told BBC.com. "But for the gharial, the unusual morphology of the snout means this is not possible. So the young have to cling to the head and back for that close connection and protection." [Source: Brandon Specktor, Live Science, September 5, 2020]

Endangered Gharials

There are about 650 adult gharials in the wild, with more than three-quarters of these living in the protected National Chambal Sanctuary in North India. On the International Union for Conservation of Nature (IUCN) Red List gharials are listed as Critically Endangered. On the US Federal List they are classified as Endangered. In CITES (Convention on International Trade in Endangered Species of Wild) they are in Appendix I, which lists species that are the most endangered among CITES-listed animals and plants.[Source: Kyle Bouchard, Animal Diversity Web (ADW) /=]

Gharails once ranged from Pakistan to Myanmar. Most gharials are the victims of dam building, net fishing and hunting for hides, trophies and protection. In the 19th century it is said a maharajah once shot 100 gharials on a royal hunt. The reptile suffered serious population declines in the mid-20th century. In the 1970s it was estimated there were only 100 gharails in the wild, 60 in India and 40 in Nepal, the only two countries where they are found.

The estimated number of gharials declined from 436 in 1997 to 182 in 2006 — a 58 percent drop across their range. within the span of one generation. A significant gharial population on India's Chambal River was decimated between December 2007 and February 2008 by what some biologists believe was pollution. The wild population of gharials has shrunk to a few hundred individuals living only in India and Nepal.

The gharial population in Nepal has plummeted by 98 percent since the 1940s due to overhunting, according to the Zoological Society of London. Most of the 200 remaining gharials live in Chitwan National Park, where they face issues with pollution, mining and declining fish populations. [Source: Sascha Pare, Live Science, June 6, 2023]

Threats to Gharials

Male Indian gharials are sometimes sought after for their ghara, the growth on the end of their snout, because it is believed by some to carry aphrodisiac properties. Eggs are collected for their supposed medicinal properties. Human fishing also causes issues. Gharials get entangled in nets and have been killed because they take fish away from fishermen. Fishing also greatly reduces the prey base of these animals. A recent threat to gharials is gout. Since 2007 over 110 gharials have succumbed to this disease which is usually associated with humans. Gout among gharials may be caused by the introduction of Tilapia into the Yamuna river. It is believed that these fish carry a toxin that effects gharials, but the composition of the toxin and how it enters the river is still being researched. /=\

Their biggest threat is habitat loss and disturbance caused by people clearing riparian environments (wetlands adjacent to rivers) areas for firewood or farmland or mining river banks for sand. Poaching is also a problem. Indian gharial eggs, hatchlings and juveniles are eaten by rats, golden jackals, wild pigs, mongooses and monitor lizards as well as other, larger aquatic and terrestrial predators.

Mel White wrote in National Geographic, “Recovery in the 1980s and 1990s, thanks to decreased poaching and establishment of protected areas, gave conservationists reason to believe it was out of trouble. But recent surveys have shown that gharial numbers have once again crashed, this time to critically endangered status. Factors in their decrease include persecution by fishermen (who see them as competitors), drowning in fishing nets, and destruction of their habitat by sand mining and other human activities. [Source: Mel White, National Geographic , November 2009]

Sand mining causes habitat loss by destroying the sand banks gharials use as nesting sites in the dry season. Young gharials are more likely to get caught in fishing nets — particularly gill nets — but adult gharials are vulnerable, too. In June 2023, an adult male gharial was found dead, entangled in a fishing net, in Chitwan National Park, Nepal. [Source: Sascha Bos, HowStuffWorks, January 18, 2024]

Efforts to Help Gharials

Biologist have had success raising gharial eggs and their increasing numbers are attributed to this. Nine hatcheries were created. Young gharails are raised in carefully monitored ponds for four years before they are released into rivers. Conservationist use long sticks to beat of the mothers to get at the eggs. With the creation of hatcheries the number of gharials increased from 250 in 1974 to 3,000 in 1992.

Conservation efforts have increased in recent years and attempts to ensure population increases are in place. Action groups such as the Gharial Multi-Task Force are comprised of regional and international crocodilian specialists that are working to help gharials. Among the problems faced by conservationists is finding good release sites for captive-bred gharials. [Source: Kyle Bouchard, Animal Diversity Web (ADW) /=]

Ancient Chinese Beheaded and Wiped out a Unique Species of Giant Gharials 3,000 Years Ago

In the 1970s, scientists discovered the fossils of an ancient, now-extinct species of gharial in the Pearl River Delta that bore the marks of ritual beheading. The fossils are now in museums in Guangdong. The South China Morning Post reported: The animals are believed to have been six meters from snout to tail and the top predator in their environment. Analysis of bone remains shows the two reptiles suffered "vicious attacks" and had been "ritualistically beheaded", possibly with an axelike weapon, the team said in an article published in a March 2022 article in the peer-reviewed journal Proceedings of the Royal Society B. "Chop marks [and] historical accounts suggest that the human-crocodilian conflict had lasted in southern China from the Bronze Age until a few hundred years ago when this unique species finally became extinct," the researchers wrote. [Source: South China Morning Post, March 11, 2022]

Lead author Liu Jun, a Hefei University of Technology professor who researches palaeontology and historical geology, said the team named the new giant species Hanyusuchus sinensis, after Tang dynasty government official and poet Han Yu, who had a legendary role in managing crocodilians that attacked humans and livestock. "Although the two gharials in the study died long before the Tang dynasty, and thus were not victims of Han, we believe that they were of the same species that Han killed," Liu said.

The reptilian remains discovered are believed to be from the 14th and 10th centuries BC, whereas the Tang dynasty lasted from the mid-7th to the early 10th century AD. "The reptiles described in Tang literature were of similar sizes and it would be highly impossible for two similar species to coexist in the same area within the span of around 1,000 years," Liu explained.

The poet Han was the author of the Proclamation for the Crocodiles, in which he commanded the reptiles to leave southern China for the ocean or risk being killed. "Let me place this injunction on the crocodiles: within three days, lead the hideous ilk and betake themselves southward to the sea," Han wrote. "If they are not gone in seven days ... Then they may be killed. The prefect will appoint skilled underlings who will carry strong bows and poisoned arrows to fight with them, and not stop until all are killed. Let there be no regrets."

The ancient Chinese "hatred of crocodilians had lasted for at least three millennia since the Shang dynasty", according to the researchers, who cited "two chop mark bearing specimens from Shang and Zhou dynasties". The Shang dynasty lasted from about 1600 to 1050BC, followed by the Zhou dynasty until 256BC. "The ancient Chinese crocodilian ... often attacked people and livestock," they said, adding that the giant reptiles lived along major river systems across today's Guangxi region, Guangdong and Fujian provinces in southern China.

To get rid of the menace, "government officials in the Tang, Song and Ming dynasties resorted to sacrificial rituals and forces in the Han River valley, eastern Guangdong". "The range of [the species] would be progressively contracted during the past two millennia, as hotspots of the population associated with intensive agricultural activities emerged in southern China."

Gharials in Nepal Turning Orange

Some gharials and mugger crocodiles Chitwan National Park in Nepal have turned orange and scientists think it's because of to iron in the waters where they reside. Some of the rivers and streams in the park have extremely high levels of iron. "Gharial and mugger crocodiles who spent lots of time in some streams, or near the mouths of them, were getting a serious fake tan," Phoebe Griffith, a postdoctoral researcher at the Leibniz Institute of Freshwater Ecology and Inland Fisheries, wrote on Twitter."Turns out some areas of Chitwan have seriously high levels of iron in the water, and iron reacts with oxygen to form an orange substance called iron oxide." [Source: Sascha Pare, Live Science, June 6, 2023]

Sascha Pare wrote in Live Science: As these crocs spend most of their time in the water — gharials are not well-suited to walking on land and typically only crawl onto sandbanks to bask in the sun or nest — the iron-rich rivers could have coated their scales and teeth in a temporary layer of rusty particles. The discolored gharials’ and crocodiles’ new orange look is temporary, and the rusty particles could wash off in less iron-rich waters. "It should go off automatically in clean(er) water," Lala Aswini Kumar Singh, a zoologist and wildlife researcher in India, wrote in a comment on Twitter.

These aren't the first rust-colored reptiles on record. A 2016 study in the African Journal of Ecology reported that orange dwarf crocodiles (Osteolaemus tetraspis) living in caves in Gabon may have turned orange after being exposed to bat guano, which contains high levels of urea — a substance with a bleaching effect that forms when protein is broken down in the liver. Iron oxide may also have tinted an orange-hued alligator in South Carolina in 2017, after it spent the winter in a rusty iron culvert.

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated February 2025