Dugong (Dugong dugon): Facts, Diet, Habitat and Status

What does a dugong look like?

A dugong has a long, rounded body that tapers at both ends, with no dorsal fin and no hind limbs. Its thick, smooth skin is pale cream at birth and darkens to brownish gray with age, though algae growing on the skin can change its color. Short, sparse hairs cover the body and probably help it sense its surroundings by touch.

The tail ends in two pointed flukes with a notch in the middle, very like a dolphin’s. The dugong swims by beating this tail up and down and uses its short, paddle-like front flippers, which have no nails, mainly for steering. The head is the most distinctive part. The snout bends sharply downward and ends in a broad, horseshoe-shaped muzzle covered in stiff bristles, ideal for grazing on the seabed.

Dugongs have small eyes and rather poor eyesight but good hearing, even though they have no external ears. Their nostrils sit on top of the head and close with valves when they dive. Males, and some old females, have a pair of short tusks, which are enlarged front teeth. Like manatees, dugongs have very dense, heavy bones that act as ballast and help them stay low in the water.

How big are dugongs?

Adult dugongs are usually 2.4–3 m (8–10 ft) long and weigh about 230–420 kg (510–930 lb), and they rarely exceed 3 m (10 ft). Females tend to be slightly larger than males. The largest dugong on record, found off the coast of western India, measured 4.06 m (13.3 ft) and weighed 1,016 kg (2,240 lb).

Where do dugongs live?

Dugongs live in warm, shallow coastal waters across the Indo-West Pacific, along roughly 140,000 km (87,000 mi) of coastline in about 40 countries and territories. Their range stretches from Mozambique, Madagascar and the Red Sea through the Arabian Gulf, India and Sri Lanka, Southeast Asia and New Guinea to northern Australia, with outposts as far as Okinawa in Japan, Palau, New Caledonia and Vanuatu. The range is patchy, and dugongs have vanished from many places where they once lived.

Northern Australia, between Shark Bay in the west and Moreton Bay in the east, is the dugong’s stronghold and holds most of the world’s population. The Arabian Gulf has the second-largest population, estimated at several thousand animals, and groups of more than 600 dugongs have been seen west of Qatar.

Dugongs follow seagrass. They favor wide, shallow, sheltered bays, mangrove channels and the calm waters behind large inshore islands and reefs, usually at depths of around 10 m (33 ft) or less, though they have been recorded feeding as deep as 37 m (121 ft). Unlike manatees, which all use fresh water, dugongs stay in the sea, entering brackish creeks and estuaries only occasionally.

What do dugongs eat?

Dugongs are seagrass specialists. They prefer small, tender seagrasses of the genera Halophila and Halodule, which are low in fiber and rich in nitrogen and starch. Using their muscular, bristly upper lip, they dig up whole plants, roots included, and leave long, winding feeding trails in the sand. An adult is thought to eat roughly 25–40 kg (55–88 lb) of wet seagrass a day.

By grazing the same meadows again and again, dugongs keep the seagrass young and tender, a habit called cultivation grazing. In cooler parts of Australia they also eat some invertebrates such as sea squirts and worms. Their diet, and why seagrass loss is so dangerous for them, is covered in detail in What do dugongs eat?

Behavior and communication

Dugongs are social but are usually seen alone or in pairs, most often a mother and her calf, because a seagrass bed rarely feeds many animals for long. Larger herds of dozens or even hundreds sometimes gather for short periods. They are shy and wary of boats and divers, which, together with the murky water they often live in, makes them hard to study.

They are semi-nomadic. Most stay within a home area for life but move with the tides to reach shallow feeding grounds, and some travel hundreds of kilometers between seagrass beds. In the cooler parts of their range they move to warmer water in winter.

A dugong usually surfaces to breathe every few minutes, typically after one to three minutes underwater, and rarely stays down longer than about six minutes. Dugongs communicate with chirps, whistles, trills and barks, and mothers and calves stay in almost constant contact, the calf often swimming just above or behind its mother.

Reproduction and lifespan

Dugongs breed slowly. Females first give birth at anywhere from about 6 to 17 years of age, and males mature at a similar age, when their tusks erupt. Mating systems vary from place to place. In Moreton Bay, Queensland, groups of males compete roughly for a single female, while in Shark Bay, Western Australia, males appear to hold small display areas that females visit, a system known as a lek.

After a pregnancy of 13–15 months, a female gives birth to a single calf in shallow water. The newborn is about 1.2 m (4 ft) long and weighs around 30 kg (66 lb). It begins nibbling seagrass soon after birth but nurses for 14–18 months, and it may stay with its mother for some time after weaning. Females give birth only every 2.5–7 years.

Dugongs are among the longest-lived marine mammals. Scientists estimate their age by counting growth layers in the tusks, and the oldest known dugong was about 73 years old. Because a female may raise only a handful of calves in her lifetime, a population can grow by no more than about 5 percent a year, even in ideal conditions.

Dugong vs manatee

The dugong is the only living member of the family Dugongidae, while the three manatee species form the family Trichechidae. The quickest way to tell them apart is the tail: a manatee has a broad, rounded paddle, while a dugong has a notched fluke. Dugongs also have a more downturned snout, feed almost only on the seabed and never live in fresh water. Their ranges do not overlap; the West Indian manatee lives on the other side of the world, in the Atlantic. All the differences are laid out in manatee vs dugong.

Relatives and evolution

Dugongs and manatees make up the order Sirenia, the only living plant-eating marine mammals. Despite their whale-like shape, their closest living relatives are elephants and hyraxes. The first sirenians appeared roughly 50 million years ago, in the Eocene epoch, and some early forms still had four legs.

The dugong’s closest relative was Steller’s sea cow, a giant kelp-eating sirenian of the cold North Pacific that grew to about 8–9 m (26–30 ft). European explorers first described it in 1741, and it was hunted to extinction by about 1768, within three decades of its discovery.

Threats and conservation status

The IUCN Red List classifies the dugong as Vulnerable. Some populations face much greater danger: in 2022 the dugongs of East Africa were assessed as Critically Endangered and those of New Caledonia as Endangered, and a survey published the same year concluded that dugongs are functionally extinct in China. They have also disappeared from Hong Kong, Mauritius and much of their former range in Japan, Taiwan and the Philippines.

The main threats come from people:

• Fishing nets: dugongs drown when they become entangled in gillnets and other nets, because they must surface to breathe.
• Hunting: illegal hunting for meat and other products continues in parts of the range.
• Seagrass loss: coastal development, dredging, pollution, runoff from farmland, floods, cyclones and marine heatwaves destroy the meadows dugongs depend on.
• Boats and noise: boat strikes and disturbance are a growing risk in busy shallow waters.

Because they breed so slowly, dugongs cannot easily recover from losses. International trade in dugong products is banned under Appendix I of CITES, and the species is legally protected in most countries where it lives, though enforcement varies. In Australia, many important dugong areas lie within marine parks with go-slow zones and net restrictions.

Dugongs and people

People have lived alongside dugongs for thousands of years. A cave painting in Malaysia thought to be about 5,000 years old shows a dugong, and for Aboriginal and Torres Strait Islander peoples in northern Australia the dugong remains an animal of great cultural importance. Traditional hunting is still permitted there under native title rights.

The name dugong comes from a word in Cebuano, a language of the Philippines, popularized by the French naturalist Buffon in 1765. Like manatees, dugongs are often said to have inspired mermaid legends, a story explored in Were manatees mistaken for mermaids? Today snorkeling with wild dugongs in places such as the Red Sea coast of Egypt draws visitors from around the world.