Why Do Male Gharials Have a Bulb on Their Snout? The Ghara

What the ghara is

The ghara is a rounded, hollow knob of soft tissue that grows over and around the nostrils at the very tip of an adult male gharial’s long snout. It sits on top of the snout’s widened end, partly covering the nostrils, so the male breathes and calls through it.

The ghara is not made of bone, but the skull beneath it changes too. In adult males the bony opening of the nose at the tip of the skull is enlarged compared with females. Together, the soft bulb and the larger opening create an air-filled chamber at the front of the head.

Females and young males have a slightly bulging snout tip, a feature of all gharials, but nothing like the pot-shaped knob of a mature male. That makes the gharial the only living crocodilian with such an obvious male ornament. In other crocodilians, males and females differ mainly in size.

When does the ghara grow?

The ghara appears only as males approach adulthood. In captive-raised gharials of known age, it started to grow over the nostrils at about 11 to 12 years old. By around 15 years it measured roughly 5 by 6 by 3.5 cm (2 by 2.4 by 1.4 in) and kept growing afterward.

Males usually begin breeding at 15 years or older, when they are about 4 m (13 ft) long and the ghara is well developed. Because it grows only at maturity, the ghara works as an honest signal: a male with a large ghara is old and big enough to breed, which matters to females choosing a mate and to rival males deciding whether to challenge him.

Sound: buzzing, hissing and popping

The ghara’s best-known job is sound. Crocodilians are vocal reptiles, and male gharials are no exception. Air pushed through the hollow chamber of the ghara is thought to resonate, producing a loud buzzing or hissing call. Reports suggest the hiss can be heard about 75 m (250 ft) away.

During the breeding season, adult males also produce sudden, very short popping sounds, each lasting only a few hundredths of a second. These pops have been heard on land at distances of 200 to 500 m (660 to 1,640 ft). Scientists think the ghara helps shape or amplify these calls, which let males announce their presence to females and rivals along a stretch of river.

Bubbles and visual signals

The ghara also matters underwater. Courting males blow streams of bubbles from their nostrils, and the ghara is believed to help produce these bubble displays.

Above the surface, the ghara is a visual signal. As a male lifts his head or patrols his stretch of river, the knob on his snout tells females, and other males, that he is mature. Courtship also includes head slaps on the water and rubbing snouts with a female before mating. Experts consider the ghara a sexually selected trait, shaped by competition for mates rather than by feeding or survival, much like a peacock’s tail or a deer’s antlers.

How the ghara gave the gharial its name

The name gharial comes from ghara, a Hindi word for a round earthen pot, because the male’s snout bulb looks like one. The species is also widely known as the gavial, a spelling that is thought to have arisen when Europeans misread the original name. In Bengali it has been called the fish-eating crocodile, a fitting name given its diet, explained in what do gharials eat?

Local languages often have separate names for males and females. In Odia, spoken in eastern India, the male is called ghadiala and the female thantiana, reflecting how different mature males look.

The ghara and gharial conservation

The ghara has not always served gharials well. In parts of Nepal and India, people once believed the ghara had special powers, for example that burning it in a field would drive away insect pests, or that it worked as an aphrodisiac. Males were killed to collect their snouts, and eggs were taken for folk medicine. There is no evidence for any of these beliefs.

Hunting is no longer the main threat, but every adult male counts in a species reduced to a few hundred breeding adults. Because males take some 15 years to mature and grow their ghara, the loss of breeding males slows recovery for many years. Learn more in are gharials endangered?