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Dugong

Description

The dugong has a large, rotund body, no discernible neck and a relatively small head and small eyes. The muzzle is large, fleshy, blunt and bristly. A fleshy, prehensile upper lip overhangs the mouth and terminates in a horseshoe-shaped disc. The males have short tusks, which are present but not erupted in the females. The flippers are broad and slightly pointed at the tip and the tail, much like that of a whale, is crescent shaped(and unlike manatees, which have spatulate shaped tails). There is a distinct ridge along the hind half of the back. The overall colour is a uniform light grey to tawny brown.

Where and when to view 

Distribution

Dugongs once occurred throughout the coastal, tropical waters of the western Indian Ocean, as well as along the Indian, Asian and northern Australian coasts.While several tens of thousands still occur off northern Australia, most other populations have declined enormously over the last 50 years, leaving a few scattered remnants. In the Western Indian Ocean and East African region, they have all but disappeared except for a population of several hundred in the Bazaruto Archipelago of Mozambique. This is probably the last viable dugong population in the Western Indian Ocean region.

Habits

Dugongs were once regarded as the only truly herbivorous marine mammal, consuming only sea-grasses (true flowering plants, not -algae), though recent evidence indicates that they also eat small sea animals. They consume up to 25 per cent of their body -weight in sea-grass each day.

Although dugongs have an estimated lifespan of some 70 years, they reproduce slowly. Females become sexually mature at about 10 years of age, the gestation is 12 months, and females bear a single calf, up to 1.2 metres in length, at intervals of three to seven years. Calves are suckled for up to 18 months. 

Family bonds appear to be strong; there are eye witness accounts of males attempting to free, females or juveniles caught in nets. They are gregarious, usually found large herds which, historically, sometimes numbered more than 600 animals, though groups of less than 10 are now more common in our region. They swim slowly, just beneath the surface, and in the clear waters off Mozambique, they can clearly be seen from the air, and sometimes boats, against the light-coloured sand. Like dolphins, they swim with an up-and-down movement of the tail. Dugongs are quiet animals, making practically no sour and creating little disturbance even when surfacing to breath, which they do every three minutes or so. They will make off if approached by a motorboat but are less wary of anchored craft (though they leave if the occupants make a noise. 

The dugong is a coastal species, inhabiting the wary shallow waters that sustain an abundance of the sea-grass This makes them particularly vulnerable to coastal-zone development and over-exploitation – their decline is directly related to increasing human presence. Hunting, the nets of fishermen, coastal development and environmental degradation have all taken their toll. 

Viewing

Though vagrant dugongs have been recorded as far south as central Umhlali, KwaZulu-Natal, their normal range is from Maputo Bay northwards. However, they have disappeared from most of the East African coast (and Mascarine Islands too) so that the only place one may see them is in the Bazaruto Archipelago. 

IUCN Status

Endangered