Sirenios

Sirenios is a term occasionally used to refer to the sirenians, a group of fully aquatic, herbivorous mammals that includes manatees and dugongs. In current scientific usage the standard name for this clade is Sirenia, and “sirenios” is not a formal taxonomic designation in English, though it may appear in historical literature or non-English texts.

Living sirenians are divided into two extant families: Trichechidae, the manatees, and Dugongidae, the dugongs. The manatees comprise three species: the West Indian manatee (Trichechus manatus), the Amazonian manatee (Trichechus inunguis), and the African manatee (Trichechus senegalensis). The dugongs include the dugong (Dugong dugon) and several extinct relatives. The Steller’s sea cow (Hydrodamalis gigas) was once a member of Dugongidae but became extinct in the 18th century.

Geographically, manatees inhabit warm coastal waters, rivers, and estuaries across the tropical Americas, West Africa, and parts of the Caribbean, with the Amazonian manatee living in freshwater. Dugongs are found in tropical Indo-Pacific seas. Both groups rely on seagrass and aquatic vegetation for food and require shallow, calm waters for foraging.

Anatomically, sirenians are large, slow-moving mammals with paddle-like forelimbs and tails adapted to aquatic life. They are strict herbivores, feeding mainly on seagrasses and other plants. They breathe air, surface periodically, and have long lifespans with relatively slow reproduction.

Conservation concerns are significant: all living sirenians face threats from habitat loss, boat collisions, entanglement in fishing gear, and climate change. Protected areas and regulatory measures exist in many regions, but populations remain vulnerable. Fossil evidence shows sirenians originated in the early Eocene, with modern lineages diverging subsequently; their closest living relatives are among the Afrotheria, including elephants.