A heavy gray animal up to 4 m (13 ft) and around 400 kg (880 lb), with a blunt downturned snout and a horizontal tail fluke like a whale's - the detail that separates it from the paddle-tailed manatees of the Atlantic. It surfaces nose-first, breathes for a few seconds and rolls under without showing the tail.
It is the only marine mammal on Earth that eats plants and nothing else. Everything about it follows from that: the snout is turned down because the food is on the bottom, the upper lip is a muscular disc that grips seagrass, and the gut is long and slow because seagrass is poor fuel. A feeding animal leaves a clean furrow in the meadow, and the trails are how surveys count a population nobody can see.
The grazing is closer to farming than to browsing. Dugongs return to the same patches and crop them repeatedly, which favors the fast-growing, nutritious seagrasses over the tough ones, so a meadow with dugongs in it is a different meadow from one without.
The arithmetic is what makes this animal fragile. A female is not mature until she is around ten, carries one calf for over a year, nurses it for eighteen months, and may raise three or four in a life that can run to seventy years. A population cannot absorb boat strikes, net entanglement or being followed by swimmers. In this sea the animals are counted in individuals and known by name, and each one that stops using a bay is not replaced.
- heavy gray body with a whale-like horizontal tail fluke, not a rounded paddle
- blunt downturned snout with stiff bristles, kept to the bottom while feeding
- surfaces nose-first for a few seconds, then rolls under without showing the tail
- length up to 4 m
