Hearing
All otters have very good hearing. Some scientists believe that an otter's sense of hearing is more important than smell for sensing danger.
Eyesight
Eyesight is probably the most important sense for hunting.
A specialized lens and cornea correct for the refraction of light caused by the transition from aerial to aquatic vision.
Vision studies conducted on Asian small-clawed otters suggest that, in bright light, visual resolution is equally good in water and air; in dim light, resolution is better in air than in water.
Tactile
Clawless otters and sea otters have very sensitive forepaws. The areas of their brains that receive tactile sensory information from the forelimbs are enlarged. These otters use their forepaws for foraging.
An otter's vibrissae are very sensitive to tactile stimulation and to underwater vibrations.
A substantial nerve network at the base of the vibrissae transmits tactile information to the brain.
In river otters and giant otters, species that forage with their mouths, the area of the brain receiving tactile information from the facial area is larger than in other species.
Taste
Otters show preferences for certain foods, but researchers don't know if taste is important in these preferences.
Smell
Otters have an acute sense of smell. It is probably the most important sense for communication about territories and assessing breeding readiness.
