Although often regarded as
marine (saltwater) species,
some dolphins live exclusively
in freshwater rivers and lakes;
others have adapted to live in
both marine and freshwater
environments. River dolphins
differ from oceanic dolphins in
several ways, including having
a much longer snout – up to 20
percent of their body length –
and extremely poor eyesight.
Most are comparable in size
(about 2.5 m) to the more