habits to its better- known relative but distinguished
by its larger size (it weighs up to 9 kg/20 lb) and two,
rather than three, prominent claws on the front feet and
four, rather than three, on the hind feet. Two- toed sloths
are more confined to primary forest than three- toed
species. Although the two kinds of sloths look similar,
the three- toed and two- toed families are only distantly
related. The two- toed sloths are considered more closely
related to the extinct giant ground sloths (chapter 8).
Because sloths spend so much time upside down,
hanging by all fours from a tree branch, their fur has
adapted, by natural selection, an orientation from the
belly to the back, the opposite of the usual direction
in mammals. The hairs of their coats are grooved and
serve as habitat for numerous insects, mites, ticks, and
algae. The algae are so abundant that sloths take on a
greenish tinge (plate 16- 39). It has been suggested (but
not demonstrated) that the greenish appearance of an
algal- dense sloth may serve to camouflage the animal
in the foliage. Sloths are reputed to become browner in
the dry season, when lack of rain results in fewer algae
inhabiting their fur.
Sloths come to the ground about once a week to
defecate at the base of a tree. Three- toed sloths dig
a small depression and cover their excrement, an
operation that takes about 30 minutes. Two- toed slots
do not dig. Descending to the ground to take care of
business is undeniably an odd behavior, and ecologists
have yet to explain it to everyone’s satisfaction. Should
you wish to look into why sloths choose to descend
to the ground to poop, at last check there were about
83,500 hits on Google to this profound and vexing
question. Or see the sidebar “Sloths and Moths.”
The most commonly seen of the anteaters
(Myrmecophagidae) are the 60 cm (2 ft) long tamanduas.
Two species occur, the Northern Tamandua (Tamandua
mexicana; plate 16- 40), in Central America and northern
South America west of the Andes, and the Southern or
Collared Tamandua (T. tetradactyla), in Amazonia as far
south as northern Argentina. Both species are similar,
with extended pointed snouts, formidable curved claws
on the forelegs, prominent ears, and a long, prehensile
tail. The coat color is variable, depending upon range.
Some animals may be pure blond, others “vested” with
black. Tamanduas are largely solitary and are active day
or night. They are equally at home digging up ant nests
in the ground or sampling the delicacies of termitaria
in trees. They excavate with their sharp front claws and
extract the insects using their extensible sticky tongues.Plate 16- 41. Bring it on. This tamandua is in threat posture.
Those sharp claws provide it with considerable measure of
protection. Photo by James Adams.Plate 16- 40. The unmistakable Northern Tamandua is a
frequently encountered anteater species, one that few forget.
Photo by James Adams.chapter 16 from monkeys to tarantulas: endless eccentricities 337