Geoscience Reference
In-Depth Information
hyraxes, and flying squirrels that seldom leave the trees. The middle canopy zone
includes arboreal mice, squirrels, bats, genets, and primates. On the ground, an
entirely different group of animals is found.
Africa has the largest number of ground-dwelling rainforest mammals, the larg-
est being the forest elephant, buffalo, bongo, okapi, and leopard. Medium-size ter-
restrial mammals include rodents, mongoose, pangolins, duikers, the smaller cats,
and otters. The great apes—gorillas, chimpanzees, and bonobos—spend time on
the ground as well as in the trees. All African mammals are placental mammals.
There is no evidence that egg-laying monotremes or pouched marsupials were ever
in Africa.
Pangolins are solitary, nocturnal mammals that feed mostly on ants and ter-
mites. They are found in the tropical regions of Africa and Asia. Four of the seven
pangolin species occur only in Africa. They range in size from the smallest, the tree
pangolin, weighing about 3.5 lbs (1.6 kg), to the largest, the giant pangolin, weigh-
ing up to 72 lbs (33 kg). All have extremely long tongues and no teeth. Pangolins'
backs are covered with a series of overlapping scales that extend from the head,
down the back, and almost to the tip of their long tail, while their undersides are
covered with a sparse coat of fur. They have short limbs adapted for digging and
large sharp recurved claws. Two species have semiprehensile tails used in climbing.
When threatened, pangolins curl into a ball, protecting their scaleless undersurface.
They lash about dangerously with their tails, which are covered with sharp-edged
scales. They may also spray a foul-smelling liquid from their anal glands. Pangolins
have relatively poor vision and hearing and locate their prey by scent. Two small
pangolins, the tree pangolin and long-tailed pangolin, spend most of their time in
the trees. The ground pangolin and the giant pangolin (the largest of all pangolins)
are primarily ground-dwelling species. Pangolins are hunted for their meat and
their populations are in severe decline. As an example of convergent evolution,
pangolins are somewhat similar in appearance and behavior to Neotropical arma-
dillos, but they are not related.
Tenrecs are limited in distribution. A few species live in the rainforest of West
and Central Africa. The largest and most diverse group occurs on the island of
Madagascar. The family has been divided into three subfamilies. The otter shrews
(Potamogalinae) live in West and Central Africa; the tenrecs (Tenrecinae) and the
aquatic, rice, and shrew tenrecs (Oryzoryctinae) are confined to Madagascar. Ten-
recs are considered direct descendants of primitive mammals as they maintain
many of those characteristics.
Otter shrews are only found in the tropical rainforests of Africa and all are
aquatic. Otter shrews are large, around 24 in (600 mm) in length and 2.2 lbs (1 kg)
in weight, and are adapted for aquatic life. Although called a shrew, the giant otter
shrew is really a tenrec and probably represents an early branch of the tenrec fam-
ily. The giant otter shrew is found only in Central Africa and lives in swamps,
streams, rivers, and forest pools within the rainforest. The giant otter shrew is noc-
turnal, hunting between dusk and daybreak. A strong swimmer, it feeds on crabs,
