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Dolphins are highly
intelligent aquatic mammals that are closely related to whales and
porpoises.
Most dolphins have
acute eyesight, both in and out of the water, and their sense of
hearing is superior to that of humans. Though they have a small ear
opening on each side of their head, it is believed that hearing
underwater is also if not exclusively done with the lower jaw which
conducts the sound vibrations to the middle ear via a fat filled
cavity in the lower jaw bone. Hearing is also used for echolocation,
which seems to be an ability all dolphins have. Their teeth are
arranged in a way that works as an array or antenna focusing the
incoming sound, making it easier for them to pinpoint the exact
location of an object. The dolphin's sense of touch is also
well-developed. However, dolphins lack an olfactory nerve and thus
have no sense of smell, but they can taste and do show preferences
for certain kinds of fish. Since dolphins spend most of their time
below the surface normally, just tasting the water could act in a
manner analogous to a sense of smell.
Dolphins are social
creatures, living in pods (also called "schools") of up to a dozen
individuals. In places with a high abundance of food, pods can join
temporarily, forming an aggregation called a superpod; such
groupings may exceed a thousand dolphins. The individuals
communicate using a variety of clicks, whistles and other
vocalizations. They also use ultrasonic sounds for echolocation.
Membership in pods is not rigid; interchange is common. However, the
cetaceans can establish strong bonds between each other. This leads
to them staying with injured or ill individuals for support. |
