Its power of vision is apparently poor, but its sense of hearing is acute. Animals beached in the open air have been found to wince at relatively faint squeaking sounds, and in the water they are easily frightened by any extraneous noises. On the whole they would seem to be defenceless and rather timid, uneasy creatures. The Dugong, like all aquatic mammals, comes to the surface of the water to breathe at intervals. It is said that it normally remains below for five to ten minutes at a time, but the spells may be much shorter, particularly if it is excited or troubled.
Breathing is accomplished quickly.
The nostrils are opened as soon as they are above the surface, and the foul air expelled and replaced by fresh in a few seconds. The expulsion of the air produces a harsh, fairly, loud, puffing sound. As far as is known the adults are mute, and this is the only noise that they make, though the young are said to bleat like calves. Thomas Browne, like many cultivated minds, was apprarently much troubled by the problem of the nature of the song that the Sirens sand. As far as the Sirenia are concerned the answer is a loud raspberry.