The beluga
is also known as the white whale for its milky white
skin. It is the only species of whale that is entirely
white, although it is born gray and fades gradually
with age. These whales lack a dorsal fin, but have a
shallow ridge along their back. Their appendages are
narrower and pointier than that of the narwhal. Belugas
also have a melon-shaped head, which is the center for
echolocation. They are 3 to 5 meters and length and
weigh an average of 1.6 tons (3500lbs). Fifty percent
of their weight is fat, a marked increase relative to
other non-arctic whales, whose body is only twenty percent
fat. The blubber is 10cm thick in belugas. Belugas are
sexually dimorphic, with the males being slightly larger
than the females.