Manatees and dugongs are marine mammals belonging to the order Sirenia. These gentle, herbivorous creatures inhabit warm waters globally. They share a common lineage but have evolved distinct adaptations. This article explores their shared characteristics, distinctive features, habitats, feeding strategies, and conservation efforts.
Shared Characteristics
Manatees and dugongs are large mammals within the Sirenian order. They share a general body plan, characterized by a robust, torpedo-shaped body, two front flippers, and a horizontally flattened tail. Their skin is gray, though it can appear brownish or greenish due to algae growth. These animals are herbivorous, grazing on aquatic vegetation.
Both species are gentle and slow-moving, earning them the “sea cow” nickname. They spend much of their time resting and feeding. Females give birth to a single calf after a gestation period of about a year, and the calf remains with its mother for one and a half to two years.
Distinctive Features
Manatees and dugongs exhibit several physical differences. The most noticeable distinction is their tail shape: manatees possess a rounded, paddle-shaped tail, like a beaver’s, while dugongs have a fluked tail, similar to a dolphin’s or whale’s. This difference in tail structure impacts their movement, with dugongs being more agile and able to change direction quickly.
Their snout and mouth structure also differ. Manatees have a shorter snout with a divided upper lip, allowing them to gather food from both the surface and submerged plants. In contrast, dugongs have a longer, broader, and downward-facing snout, adapted for grazing on seagrasses rooted on the seafloor. Adult male dugongs and some older females also develop small tusks, which are absent in manatees. Manatees have a unique “marching molars” system where new teeth continuously grow at the back and move forward as old teeth wear down.
Habitats and Feeding
Manatees and dugongs occupy different aquatic environments, reflecting their feeding habits. Manatees inhabit fresh, brackish, and saltwater environments. West Indian and West African manatees reside in saltwater but migrate to warmer freshwater areas during colder months. The Amazonian manatee lives exclusively in freshwater.
Manatees prefer shallow, marshy coastal areas and rivers, where they find aquatic plants. Their diet includes plants like sea clover, kelp, various algae, and mangrove leaves. They graze for six to eight hours a day, consuming about 10-15% of their body weight daily.
Dugongs are strictly marine mammals, never venturing into freshwater. They are found in warm, shallow coastal waters of the Indian and western Pacific Oceans, from East Africa to Australia. Their habitats are characterized by abundant seagrass beds, forming almost their entire diet. Dugongs use their downward-pointing snout and muscular upper lip to uproot entire seagrass plants from the seafloor, often leaving visible feeding trails.
Conservation Efforts
Both manatees and dugongs face threats to their survival, leading to conservation efforts. Manatees are threatened by cold temperatures and collisions with vessels. Their slow nature makes them vulnerable to boat strikes. Habitat loss and degradation, due to coastal development and pollution, also pose dangers.
Dugongs are listed as vulnerable by the International Union for Conservation of Nature (IUCN), with some populations, like those in East Africa, classified as critically endangered. Threats include unintentional capture in fishing gear and habitat destruction of seagrass beds. Historical hunting for meat and oil also contributed to population declines. Conservation initiatives protect the animals and their seagrass habitats, minimize fishing gear entanglement, and address impacts of boat traffic and coastal development.