Manatees, often called “sea cows,” are large, gentle marine mammals belonging to the order Sirenia. They inhabit warm, shallow coastal waters, rivers, and estuaries. These herbivores spend much of their time grazing on aquatic vegetation. As they navigate these varied waterways, their appearance can change dramatically, leading to questions about their actual color. This article explains the manatee’s natural coloration and the biological reasons for their occasionally green look.
The Manatee’s Base Color and Skin Texture
The natural color of a manatee’s skin is generally a uniform shade of gray to brownish-gray. Their skin is remarkably thick, possessing a rough, leathery, and finely wrinkled texture, similar to that of an elephant, their distant terrestrial relative. This thick skin acts as a protective barrier in their aquatic environment.
Their entire body is sparsely covered with fine, colorless hairs, known as vibrissae. These sensory bristles are denser around the muzzle but are distributed across the skin, allowing them to perceive changes in water pressure and current. The skin itself is continually flaking off, which helps reduce the build-up of organisms on their surface.
Why They Often Appear Green
Despite their base gray coloration, manatees frequently appear green or dark brown, especially when observed near the water surface. This visual change is not due to a shift in skin pigment but is caused by the opportunistic growth of aquatic organisms on their bodies. Algae, diatoms, and small invertebrates, like barnacles, attach themselves to the manatee’s rough, textured skin.
Because manatees move at a slow pace, they provide an ideal, mobile surface for aquatic organisms to colonize. The green appearance is the direct result of photosynthetic algae thriving on the manatee’s back, flippers, and tail. The extent of this growth fluctuates based on the water’s temperature, salinity, and nutrient content.
Manatees in saltwater environments may accumulate small barnacles, which contribute to a mottled appearance. When a manatee travels from a salty habitat to a freshwater spring or river, the change in salinity causes these saltwater-dependent organisms to detach. This constant change illustrates the dynamic nature of a manatee’s outer appearance.
Coloration and Camouflage
The manatee’s gray-brown color provides effective natural camouflage in its habitat. Their primary environments are often murky, silt-filled waters, including river mouths, shallow coastal flats, and estuarine areas. The muted color allows them to blend in seamlessly with dark river bottoms and the shadows of seagrass beds where they feed and rest.
The layer of green algae and diatoms that frequently coats their skin enhances this natural camouflage. This biological covering helps them disappear into the aquatic vegetation, reducing their visibility. This aids in their overall protection while they graze in shallow, plant-rich waters.