DOLPHINS, OTHER EXOTIC ANIMALS LIVE IN THE AMAZON
by Whit Gibbons
July 14, 2003
you ever seen a pink dolphin or a river five miles wide and a hundred
feet deep? I have. I just returned from the Amazon, where such sights
are to be expected.
ecologists are often advised to experience "the tropics" in
order to appreciate the diversity of life and the multitude and complexities
of species interactions. My own experiences in tropical regions have
confirmed for me that they do indeed offer intrigue and biological mystery
for anyone who is fascinated by the natural world.
Amazon is unsurpassed for magnitude in all tropical environment categories.
It is the mightiest of all natural environmental areas remaining in
the world. Consider the following facts. The country of Brazil is approximately
the size of the continental United States, and the upper half encompasses
the Amazon River, which we all are familiar with by name. The Amazon
Basin, the watershed that collects the water that forms the Amazon River
from numerous tributaries, extends into Peru, Colombia, and a few other
South American countries. Try to visualize the extent of this watershed,
which covers more land area than a rectangle from Oregon to Maine to
Florida to southern California. Imagine a single river that collects
all the rainfall each year that falls inside the rectangle. An Australian
friend told me that the Amazon River transports more water on one rainy
day in the wet season than all the rivers in Australia carry in a year.
I believe him. The river is enormous.
is the essence of the Amazon, and the annual transitions from wet to
dry seasons control the events in the lives of Amazonian plants and
animals, including people. The river system has what is comparable to
a single tide schedule each year. During the dry season, which is roughly
from June to December, the water levels of the river may fall more than
forty feet below the average high water level. Last week I saw river
freighters afloat in a three-mile-wide section of river where they would
be grounded on a beach with sunbathers in a few more weeks.
have made and will continue to make countless wildlife observations
about the natural wonder known as the Amazon. One colleague returned
from a five-day excursion into the jungles. He was intrigued by the
Amazonian bird life and said the bird color patterns he saw were as
if a three-year-old child had randomly picked the brightest colors from
a box of crayons and colored the birds. I saw some of these birds, and
the color spectrum is fully represented.
colleagues were amazed by a fish that had been discovered the previous
week. I saw the animal in an aquarium, as it stood upright underwater
with its mouth at the surface, breathing air. The creature looked like
a brown drinking straw with a single fin that went the length of its
body across its back and under its belly. The fish was of more than
casual interest from a scientific perspective: the ichthyologists did
not know what species, genus, or family this air-breathing fish belongs
to, and apparently it did not belong to any yet described order of fishes.
Such discoveries can happen in the Amazon when scientists are on the
not sure what was most fascinating to me, but the pink river dolphins
bring an awareness of the biological strength and power of this freshwater
ecosystem. The fact that a river system can be so immense and long-lasting
that typical sea creatures, including stingrays as well as dolphins,
can evolve into freshwater forms is hard to comprehend. And, by the
way, two species of freshwater dolphins inhabit the Amazon River. A
small gray form lives in some of the same regions as the pink one. Entire
oceans have been involved in the evolution of different species of dolphins,
and the fact that two species have developed their own identity in a
river bespeaks volumes about the size and nature of that river.
Amazon is truly the big top of the world's environmental attractions,
with thousands of spectacular sideshows to keep anyone entertained.
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