EXPLORING BIODIVERSITY: A Guide for Educators Around the World

Malaria once infected nine out of ten people on
the island of Borneo, now shared by the countries
of Brunei, Malaysia, and Indonesia. In
1955, the World Health Organization (WHO)
began spraying dieldrin (a pesticide similar to
DDT) to kill malaria-carrying mosquitoes. The
program was so successful that the dreaded
disease was almost eliminated from the island.
However, unexpected things happened. The
dieldrin killed other insects, including flies and
cockroaches living in people’s houses. The
islanders applauded. But then small lizards that
also lived in the houses died after gorging themselves
on dead insects. Then cats began dying
after feeding on the dead lizards. Without cats,
rats flourished and began overrunning the
villages. Now people were threatened by sylvatic
plague carried by the fleas on the rats.
RAINING CATS
On top of everything else, roofs began to fall in.
The dieldrin had killed wasps and other insects
that fed on a type of caterpillar that either
avoided or was not affected by the insecticide.
With most of its predators eliminated, the
caterpillar population exploded. The larvae
munched their way through one of their
favourite foods, the leaves used in thatching
roofs. The situation was brought under control
when WHO parachuted healthy cats onto parts
of the island. In the end, the Borneo episode
turned out all right; both malaria and the
unexpected effects of the spraying program were
brought under control. Nonetheless, it shows
the unpredictable results of interfering in an
ecosystem.
Story adapted from: Living in the Environment, Fifth Edition. G.
Tyler Miller, Jr. (Wadsworth Publishing Company, 1988).
A Watery World
Diversity doesn’t end at the water’s edge. In fact, an
incredible variety of living things inhabit the
world’s lakes, rivers, wetlands, and oceans. A
single coral reef, for example, can support more
than 3,000 species of fish and invertebrates, such
as giant clams, sea urchins, sea stars, and shrimp.
Hectare for hectare, there can be more life in a
healthy wetland than in almost any kind of habitat.
Take mangroves, for instance. These rich wetlands,
which are found along many of the world’s
coasts, are nurseries for some of our most commercially
important species, including shrimp, crabs,
oysters, and fish. They also provide a variety of
ecosystem services including flood control, water
purification, and food and shelter for a host of
aquatic creatures.
Culture and Nature
The diversity of human cultures is also an important
part of biodiversity. All humans belong to a
single species (Homo sapiens), but within our
species are thousands of different cultures. There’s
evidence to show that the natural world is nearly
as important in influencing the development of
different peoples as it is in influencing the evolution
of different plants and animals. For example,
cultural practices are often heavily influenced by
environmental conditions. In arid places such as
the Sahara or Kalahari Deserts in Africa, people
developed nomadic cultures, moving around from
place to place in search of resources, rather than
settling in one place for a long time. Agricultural
communities have stories and proverbs that are
passed from one generation to the next that tell
when and how to plant crops depending on local
climate and other environmental factors.
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