Sirenians

Sirenians are an order of large, herbivorous aquatic mammals that include the manatees and the dugongs. Commonly known as sea cows, they inhabit warm, shallow coastal waters and river systems in tropical and subtropical regions of the Americas, Africa, and Asia, feeding on aquatic vegetation such as seagrass and freshwater plants.

There are two surviving families: Dugongidae, which includes the dugong (Dugong dugon); and Trichechidae, which includes the three species of manatees: the West Indian manatee (Trichechus manatus), the Amazonian manatee (Trichechus inunguis), and the African manatee (Trichechus senegalensis). Manatees have broad, paddle-shaped tails, while dugongs possess a horizontally fluked tail. Both lack hind limbs and have paddle-like forelimbs with sparse hair and sensitive, flexible snouts adapted for grazing.

Ecology and behavior: Sirenians are slow, coastal herbivores that graze on seagrass beds and other aquatic vegetation. They surface to breathe and can stay submerged for several minutes. They are generally solitary or live in small, loosely connected groups and prefer calm, shallow habitats.

Reproduction and life history: Females give birth to a single calf after long gestation, about 12 to 14 months. Calving intervals are typically 2 to 3 years. Calves remain with their mothers for up to two years, and overall lifespans reach several decades.

Conservation: All living sirenian species face threats from habitat loss, seagrass decline, entanglement in fishing gear, boat strikes, and pollution. They are protected across their ranges, and IUCN Red List statuses range from Vulnerable to Endangered depending on species and region. Historical species such as the Steller’s sea cow were driven to extinction by human activity.