to good use as they search for food among the trees
of the flooded forests. They do not have keen eyesight
but have effective sonar, permitting them to navigate
among the dense trunks of the forest.
The second dolphin species is Sotalia fluviatilis, the
Tucuxi (pronounced too- coo- she) or Gray Dolphin.
Tucuxis are smaller and darker than Botos, reaching
no more than 1.5 m (5 ft) in length. They have a shorter
snout, much less bulbous head, and a more distinctive
triangular dorsal fin. They normally show much of the
head when they surface, and they often leap from the
water. Tucuxis are found in larger groups than Botos,
of from two to nine. Tucuxis are scarce or absent in
most of the Orinoco Basin, probably due to seasonal
changes in water depth. In the Amazon, Tucuxis are
found typically in deeper waters than Botos. Tucuxis
are so characteristic of deeper waters that river pilots
observe them for navigational aids.
A manatee more or less resembles a huge sausage
with a small, puffy- looking head adorned with a wide,
blunt snout and short whiskers. The body tapers into a
fan- shaped tail used to swim. The forelimbs, adapted
as flippers, are small. Manatees are in the mammalian
order Sirenia (the name refers to the fact that these
odd, homely animals were allegedly once mistaken
for mermaids, or sirens). There are only three extant
species, though some authorities argue that there are
four. The Amazonian Manatee (Trichechus inunguis)
is a close relative of the larger West Indian Manatee
(T. manatus; plate 12- 14). The Amazonian Manatee
reaches a length of about 2.8 m (approx. 9 ft) and can
weigh up to 500 kg (1,100 lb). It ranges throughout
much of the Amazon and its major tributary rivers, but
it takes luck to see it, as it has been reduced throughout
its range to the status of endangered species. Hunted
for meat, oil, and hide, this once abundant creature,
though now protected, still suffers persecution. The
similar West Indian Manatee fares a bit better, enjoying
protection, especially where it occurs along Florida’s
coast and rivers.
Manatees are strict vegetarians, harvesting plant
material such as water lettuce and water hyacinth.
They are social animals, usually in small groups. The
only time they tend to be aggressive is when they are
attempting to mate and tensions mount.Capybara: Master of the Grasses
The Capybara (Hydrochoeris hydrochaeris; plates
12- 15– 16), growing to 1.3 m (4 ft) long and 100 kg
(about 220 lb), holds the title of the world’s largest
extant rodent. A slightly smaller species, the Lesser
Capybara (H. isthmius), occurs in northern South
America, from eastern Panama through parts of
Colombia and Venezuela. Both Capybara and Lesser
Capybara are essentially identical in their ecologies.
This account focuses on the larger Capybara. Ranging
throughout most of lowland South America, from
Panama to northeastern Argentina, the Capybara is
aquatic, ecologically similar to the much larger African
hippopotamus. A stocky, essentially tailless, caviomorph
rodent (thus related to guinea pigs), the Capybara has a
pale tan coat and short, thick legs. The toes are partially
webbed, and the eyes, ears, and nostrils are located oncruising the rivers to the seaPlate 12- 13. The Pink River Dolphin often allows close
approach from boats. Photo by Andrew Whittaker.
Plate 12- 14. West Indian Manatees reach as far north as the
central Florida coast. Photo by John Kricher.214 chapter 12 cruising the rivers to the sea