It is believed that they can differentiate between colors. It is unclear how manatees navigate in pitch black or murky waters - when their eyesight would be of no use. They do have sparse body hair over their bodies, and thick whiskers on their faces. It is not clear if this aids in navigation. One expert is convinced, however, that they know exactly where swimmers are, even in black-out conditions.
Manatees can hear very well despite the absence of external ear lobes.
They are not believed to have the capabilities of echo-location. Emit sounds that are within human auditory range. They make sounds such as squeaks and squeals when frightened, playing, or communicating, particularly between cow and calf. No air is released from the manatee when these sounds are made, and it is not clear where the sounds are being produced or if they serve any other purpose. Manatees are mammals and breath air through their noses at the surface - with nostrils which close tightly when submerged.