_Sight_
Little is known, however, about the capabilities of the various sensory
organs. Certainly the eyes are very important and are effective under
water. It is not likely that the eye is very effective out of water,
even though whales do elevate the head out of the water for a look
around. The behavior has been appropriately called "spyhopping," and it
is manifested usually in the ice floes. Killer whales are believed to
search the sea's surface and the edge of the icebergs for seals and
birds.
_Hearing_
Whales appear to have very acute hearing. The report of a whaling gun
will alarm whales which have previously tolerated the whaling vessel
close aboard. Whalers have noted that in very foggy weather whales are
much more difficult to approach because of the increased sensitivity to
noise. The toothed cetaceans which are gregarious are capable of a great
variety of vocalizations. Much of this is ultrasonic to man and it has
been suggested that these emissions are used like man's sonar for
finding obstacles and food. Considering the limited range of vision
possible in water which is usually hazy or turbid, such a feature would
be most useful. There is a continual chatter among members of a porpoise
school, or gam, as the whalers call them. The accumulated noise serves
as a beacon to which straying members can home when they have gotten out
of visual range, which incidentally is under 300 feet. No one yet knows
exactly how these animals can produce these sounds without being able to
move air across the vocal chords. They do not exhale under water, and
yet they are continually noisy.
_Smell_
The sense of smell is not important to whales, and the organ was
abandoned when the nostrils were shifted to the back of the head and
modified for diving. Although man may never be able to test whales
experimentally for their sensual acuities, it is quite apparent that
they are fully aware of their environment. They clearly recognize the
environmental signposts which guide them to and from their various
areas. Oceanographers are not nearly as adept in knowing where they are
on the ocean. Whales clearly recognize their own particular kind, and
they do not intermingle. Incidentally, man finds it difficult to
differentiate some of the whale species. Because of the rarity of
specimens and information, the identity of some species may still be in
doubt.