From: itannman@boris.ucdavis.edu (Ann Mansker)
Subject: Critter of the Week: Inia geoffrensis
Date: 28 Sep 1998 00:00:00 GMT
Newsgroups: ucd.life

The boto, or Amazon River Dolphin, is the largest of the world's 5 species
of freshwater dolphins, inhabiting the Amazon and Orinoco river basins.
They are found in calm parts of the rivers during the dry season, but
spread into the forest during the annual rainy-season floods.  They swim more
slowly than their oceanic cousins, but have a more flexible body and
greater agility.  They maneuver easily among the trees, catching fish that
feed on forest fruits.  At this time they are solitary, though when the
rivers return to their channels they sometimes gather in small groups for
feeding and mating.

Botos are born gray, but the pigment fades as the dolphin matures, unless 
it inhabits a clear, sunny stretch of the river. Since they spend their
lives in warm waters, botos lack the white blubber layer of other
cetaceans; as they lose pigment they turn pink.  The color deepens under
exertion, indicating that it comes from the flush of blood in capillaries
under the skin, like a human blush.  Another common name is pink dolphin.
This is clearly seen in the several (unfortunately small) images at
http://www.photoamazonica.com/reports/boto.htm .

Like most dolphins, botos seem to have a liking for humans, and will
sometimes play with them.  Until recently, this was a fairly safe
behavior, as local legends prevented them from being hunted.  As more
outsiders invade the rivers, however, they are sometimes perceived as
competitors for fish and killed.

Botos have several unique characteristics.  They are the only dolphin
species that retains any hair at all as an adult.  The small hairs on
their snout may give them some tactile feedback as they search the river
bottom for crustaceans.  They have some molar-like teeth, and can chew
their food; most dolphins have conical, peglike teeth that are excellent
for grasping slippery fish, but useless for anything else, and they are
forced to swallow their food whole.  Boto have a flexible, visible neck.

Images of boto on the web are rarer than the creature itself.  There is a
QuickTIme clip at
http://arkive.uwe.ac.uk/species/Pink_River_Dolphin/Pink_River_DolphinV.html