Although the manatee lacks eyelids as we know them, it can still blink to protect its eye. The ears of the manatee are internal, with no external lobes, but the underwater hearing of the animal is quite good. Manatees produce squeaks and chirps. It is not known for sure why, but it is suspected that they could range from alarm calls, to expressions of happiness. Most scientists believe that the manatee does not use these sounds for echolocation like a dolphin would.
Breathing occurs through a pair of nostrils located on the top of the nose.
The manatee can close off its nostrils when diving in order to keep water out. This allows the manatee to make more efficient use of its trips to the surface. Manatees normally breathe every 2 to 5 minutes, but can stay submerged for as long as 20 minutes if necessary. The mouth of the manatee contains rows of molars, for chewing the tough plants which make up the animal's diet. As these teeth are worn down by the plants, they are replaced with new ones growing in from the back.