Manatees have made their way back to docks of the South Seas Island Resort Harbourside Marina.
While watching the manatees surface at the marina, we observed, along with multiple scars, that manatees are quite hairy for a marine mammal.
There are some defining characteristics that all mammals share, whether they live in the water or on land. For example, mammals are warm-blooded, breathe oxygen from the air, and have hair at some point in their life. If you have ever touched a dolphin in captivity, you probably don’t remember it feeling furry. That’s because dolphins and other toothed whales only have hair in the prenatal stage.
Although manatees might not feel furry to the touch either, they do have visible hairs over their entire body. These are special hairs, called vibrissae, that help mammals sense things in their environment. These hairs have a unique structure, called a follicle-sinus complex in which the hair follicle and the nerves associated with it are surrounded by a blood sinus.
In most mammals, these type of hairs only occur in the region of the face (i.e. whiskers), but on a manatee, the hairs all over its entire body have the follicle-sinus complex, offering the manatee an extra sensory ability.
A manatee’s vision is not the best in the animal kingdom, and they have been observed rising in unison to the surface to breathe and feeding with their eyes closed. The vibrissae that cover their bodies could help them sense manatees or other objects in the water nearby, along with water movements and vibrations moving through the water. Scientists have compared the function of the manatee’s hairs to that of a fish’s lateral line.
The sparse hairs on the manatee’s back won’t do much to keep it warm, but could be essential to their sensory system!
For more information check out these papers:
Reep, R.L., Marshall, C.D. and Stoll, M.L. (2002) Tactile hairs on the postcranial body in Florida manatees: a mammalian lateral line?. Brain, Behavior and Evolution, 59: 141 – 154.
Sarko, D.K., Reep, R.L., Mazurkiewicz, J.E. and Rice, F.L. (2007) Adaptations in the structure and innervation of follicle-sinus complexes to an aquatic environment as seen in the Florida manatee (Trichechus manatus latirostris). The Journal of Comparative Neurology, 504, 217-237.