Finless
porpoises are one of the smallest cetaceans. They are
generally shy, apart from those living in the Yangtze
River, China, which are familiar with heavy boat traffic.
They are similar to Irrawaddy dolphins save for the
fact that they don't have fins. They are pale grey-blue
in colour with a small mouth that curves slightly upwards
and a slight depression behind the blowhole. They are
the only porpoises to have a bulbous melon. Instead
of a fin, they have a ridge along their backs which
runs from above the flippers to the beginning of their
tail stock. This ridge is covered in circular wart-like
tubercles or bumps
