Geoscience Reference
In-Depth Information
form long columns with a combined front, traveling at a rate of 65 ft (20 m) per
hour, as they swarm through the rainforest in search of prey. They attack other
insects, as well as small vertebrates, including birds, and virtually any animal in
their path. When a prey item is too large for one ant to carry, the group divides the
prey into ant-size pieces and the group returns to the nest with each part. Hunters
report that during the rainy season, pythons will search the area for driver ants
before consuming prey. Once the snake has eaten a larger animal, it is unable to
move quickly, making it more vulnerable to swarms of driver ants.
Weaver ants are canopy ants, spending their entire life within the forest canopy.
These ants weave their nests using a plant's leaves and the silk produced by their
larvae. Other ant species have evolved particular symbiotic relationships with cer-
tain plants in the forest. Some rainforest plants have nectaries outside the flower to
facilitate visits by ants. The ants use the nectar, high in carbohydrates, as their
food, and the plant as their shelter, and in the process defend the plant against pre-
dation by other herbivorous insects. These nectaries are usually located near the
most vulnerable part of the plant, such as new leaves and stems.
Bees are important pollinators in the African rainforest. Honeybees are among
the most evolved members of the order and are thought to have originated in
Africa, where their diversity is greatest. Most honeybees are excellent fliers and if
threatened can render a poisonous sting. The Africanized honeybees in other parts
of the world are introduced bees or hybrids of African honeybees that are aggres-
sive and quite troublesome.
Arachnids are numerous in the rainforest. Burrowing scorpions, crawling scor-
pions, flat scorpions, thick-tailed scorpions, whip-tailed scorpions, as well as others
live within the rainforest. West Africa is home to the largest scorpion; large and
black, the emperor scorpion is 6-8 in (15-20 cm) in length. Most are nocturnal
predators. Spiders are also abundant in the rainforest. Spiders are carnivorous,
feeding mainly on insects.
Numerous other arthropods play important roles in the life of the tropical rain-
forests of Africa. Millipedes are scavengers, decomposers of vegetation and ani-
mals. Centipedes are carnivorous, feeding on other arthropods, worms, and small
vertebrates. Insects such as grasshoppers, crickets, stick and leaf insects, cock-
roaches, mantids, flies, and fleas all exploit different niches within the forest.
Human Impact on the African Rainforest
Humans have greatly affected the tropical rainforests of Africa. Although humans
may have originated in or near the forest, they quickly moved to environments that
are more hospitable. It was not until 900
B
.
C
. before they returned to the forest.
Most were small groups of people living off the forest by hunting and gathering, or
small-scale shifting agricultural groups that seem to have had little impact on the
rainforest. Even as recently as 800 years ago, human impact on the forest was
