THREATENED SPECIES
OThe word “organism” refers to any
living thing.
OThere are different ways of classifying
organisms. They change as more
information is discovered about species.
OAll living things are linked to others.
This is how a food chain works: if parts
are missing, the chain may collapse. This
could lead to species dying out.
OBacteria can be harmful or helpful:
E. coli bacteria cause disease, but
penicillin can cure some illnesses.
OThe organism that makes bread go
moldy is a fungus.FAST FACTS
Bacteria are the simplest form of life.
They are single-celled organisms that
are too small to see without a
microscope. Bacteria can live in the
air, in water, and even inside bodies.Protists are basic life-forms. Most
protists are single-celled and are
microscopic, but some group
together and are more easily seen,
such as algae on a pond.
PRODUCERS such as
plants are the first stage in a
food chain. Plants need energy
from sunlight, nutrients from
the soil, and water to grow. PRIMARY
CONSUMERS, such as
gerbils, are the first animals in
a chain. They are herbivores—
animals that eat only plants. SECONDARY
CONSUMERS are
carnivores—animals that
eat meat. SCAVENGERS AND
DECOMPOSERS Scavengers eat
dead animals, helping to break down
organic matter. Maggots, fungi, and
bacteria are major decomposers.In every kingdom, there are species
that are under threat of extinction.
There are many reasons why a species fails
to continue, from habitat loss to disease
to poaching ( p. 80–81).Striped hyena
Hyaena hyaenaFennec fox
Gerbil Vulpes zerda
Meriones sp.
Desert shrub
Fagonia sp. Nearly 30 percent of
amphibians are under threat.
Poison dart frogs are being wiped
out along with their forest habitat.FOOD CHAINS
The International Union for the
Conservation of Animals (IUCN) has
researched more than 1.5 million animal
and plant species to create their Red List of
Threatened Species. They found that:O in 2008, nearly 1,000 animals and plants
became extinct or extinct in the wild;O more than 16,000 other species are
under threat of extinction. More than one
out of every five
mammal species are
threatened with
extinction, including the
Pére David deer. Plants are also at risk,
with more than 8,000
species under threat,
including the
lady’s slipper
orchid.Most of the animals in this chapter
appear on the IUCN Red List.
Those with red triangles are at risk
of extinction, and may already be
extinct in the wild. Yellow triangles
show species that are vulnerable—
they risk becoming endangered in
the near future. Green triangles
mean there is little or no risk of them
becoming endangered at present.Which species are at risk?LIVING WORLDLIFE ON EARTH85