Exploring the Key Differences Between Dugongs and Manatees

As documented in the archives of this site, I have an unwavering fascination with manatees. I’ve adored them, supported them, and even persuaded everyone around me that I must own at least three tea infusers shaped like them. However, as I grew older, I discovered that these majestic, wrinkled-faced creatures aren’t the only charming marine herbivores. My beloved manatee shares the spotlight with its equally magnificent cousin, the flat-snouted dugong.

"Dugongs are the nearest living relatives to manatees," explains Gillian Spolarich, international communications manager at Oceana, an organization focused on ocean conservation, in an email. "Both species are herbivores, mainly feeding on seagrass and spending the majority of their time in seagrass habitats."

According to the Australian Museum, dugongs are described as "large, grayish-brown, bulbous creatures with a flattened, whale-like tail." They feature paddle-shaped flippers, lack a dorsal fin, and possess a wide, flat snout and downward-facing mouth, perfectly adapted for grazing on their preferred seagrass diet. With small eyes and ears, dugongs, much like manatees, depend little on their senses for survival, focusing instead on their plant-based foraging.

Manatees Inhabit Freshwater, Dugongs Prefer Saltwater

Although dugongs share a plant-based diet with their manatee relatives, they stand apart in one key aspect: they never venture into freshwater. This makes them the sole marine mammal that is entirely herbivorous. A poignant detail from the Oceana website both touches and saddens me: "... like most herbivores, the dugong's brain is relatively small compared to its body size, likely because it doesn't need to devise complex hunting strategies to catch prey."

Key Distinctions Between Dugongs and Manatees

"Dugongs are frequently confused with manatees, but they possess distinct characteristics," Spolarich notes. "Manatees feature rounded, paddle-shaped tails, whereas dugongs have fluked tails resembling those of whales. Manatees tend to grow longer and weigh more than dugongs. Often called sea cows, they use their powerful, split upper lips to feed on seagrass they pull from the ocean floor. Dugongs, on the other hand, can live up to 70 years, reach lengths of 13 feet (4 meters), and weigh up to 595 pounds (270 kilograms)."

What Are the Habitats of Dugongs?

Spolarich explains that while manatees inhabit the western Atlantic coasts, dugongs are found in the warm regions of the Indian and western Pacific oceans. Similar to manatees, female dugongs attract multiple males during mating season and typically mate with one or two. After a lengthy gestation period of 12-14 months, a single calf is born and nurses for up to 18 months. Calves remain close to their mothers for several years, and females reproduce only once every 2.5 to 7 years. Although adult dugongs have no natural predators, juveniles are vulnerable to saltwater crocodiles, killer whales, and large coastal sharks.

While dugongs lack natural predators, they face a significant threat from humans. "Dugongs are safeguarded by the Endangered Species Act (ESA) and listed as vulnerable on the International Union for Conservation of Nature's (IUCN) Red List," Spolarich states. "They remain endangered in certain areas due to habitat loss, boat collisions, and accidental capture in fisheries (known as bycatch). At Oceana, we advocate for science-driven policies to restore ocean health and protect these vital habitats. In the U.S., the ESA is under threat in Congress. Those who wish to support dugongs and other marine life can urge their Members of Congress to reject any legislation that undermines this crucial law."