There is only one species of dugong. Dugongs are the smallest member of the order Sirenia, which also includes manatees (three species) and the Stellar sea cow (now extinct). Adults grow to less then 3 meters long long and can weigh up to 400 kilograms — as much as five men. They look similar to seals and walruses, but are in fact more closely related to the elephant.
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Dugongs, like dolphins and whales, are mammals adapted for life in the ocean. But unlike cetaceans, dugongs are not designed to hunt and are slow-moving and graceful herbivores.
The dugongs’ large range is thought to span 37 countries and includes tropical and sub-tropical island and coastal waters. They live in the coastal areas of the Indian Ocean, the Indonesian archipelago, and the southwestern Pacific around the Philippines. But they are likely to be extinct in much of this range, or populations fragmented.
Usually found in coastal waters, the dugong frequents wide shallow bays and mangrove channels, plus the lee of inshore islands.
The dugong spends much of its time feeding and consumes up to 25 kilograms of sea grass each day.
Adaptations for life in the sea include a streamlined body, a wedge shaped tail and strong flippers. As mammals, dugongs are air-breathing and must return to the surface to breathe every five to 10 minutes. Their nostrils are at the front of their head allowing them to breathe with the rest of their bodies underwater.
Feeding is dugong’s principal activity, typically in water 1.5 meters deep. Digging or rooting is probably part of the feeding behavior. Frightened animals can make a whistling sound while calves can give bleat-like cries. Though now rare, herds of several hundred animals were formerly known. Average swimming speed is 6 mph.
Dugongs are usually either solitary or in loose herds of up to 30 animals, that move around slowly together. Herds of several hundred animals have been reported.
With a 70-year lifespan, dugongs mature around age 9. After mating and a 13-month gestation, females give birth to a single calf. Population growth is very slow as a female will only give birth every two and a half to five years. A calf suckles for around 18 months.
