Sheet 12.1 Revision Ecological terminology
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Sheet 12.1 Revision
Ecological terminology
New words for new ideas
Over the last hundred years, new ideas about organisms and how they interact with the world
around them have arisen. To explain these new ideas, new words developed. At first they
were only used by scientists, but as people have become increasingly aware about the
environment they have become more widely used.
Species
A species is made up of only one type of organism. Organisms can only be the same species
if they can reproduce and their offspring can go on to reproduce again. For this reason, all
dogs are the same species because their puppies could grow up to be parents too. However,
horses and donkeys are not the same species, because if they breed they produce mules, and
mules cannot reproduce themselves. Today there are at least 2 million different species of
organisms on Earth, but millions more have become extinct over the past 650 million years.
species Organisms that can breed and produce fertile offspring
Figure 2.8: Mules are not a
species because they cannot
reproduce themselves (you
cannot breed a mule from
other mules)
Niche
The niche of an organism is its position or function in its ecosystem (ecosystem is discussed
below). The niche a species occupies is essentially how it responds to the resources and
competitors around it. For example, the niche of a tui includes what it eats, what it does, what
Science for the New Zealand Curriculum Year 11
© Donald Reid, Geoffrey Groves, Colin Price, Ian Tennant 2011
Published by Cambridge University Press www.nzscience.co.nz www.cambridge.edu.au
Sheet 12.1 Revision Ecological terminology
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affects it and how it affects other organisms. Each species has its own niche and its niche is
different from the niches of other species.
Population
A population is the total number of individuals of one species that are living in the same place.
For example, the population of kakapo in New Zealand is 93 birds. Here the species is
kakapo, the place is New Zealand and the total is 93 birds.
Habitat
A habitat is the place where an organism lives – for example, a mountain lake. One habitat
can have many niches, which is why a single habitat can support many different species.
Ecosystem
An ecosystem is all the organisms living in an area and the environment around them. The
organisms interact with each other and with their environment. For example, an ecosystem
might be ‘a cold mountain lake full of plants, insects, fish and decomposers’.
Community
A community is all the plants, animals and micro-organisms living in an area. For example, a
community might be ‘the plants, insects, fish and decomposers in a lake’. A community is
like an ecosystem except it does not include the environment around it.
Biodiversity
Biodiversity means
that there are many different species living in an area. When an area is
biodiverse, individuals of a species are also varied. Natural, unaltered environments are
biodiverse. A lack of biodiversity means there is only one or two species present. This is a
sign of a sick ecosystem.
niche An organism’s position or function in its ecosystem
population The total number of individuals of one species that are living in the same place
habitat The place where an organism lives
ecosystem All the interactions of the organisms and their environment within a particular area
community All the organisms in a particular area
biodiversity When there is a large number of different species
Flow of energy
To compare different ecosystems such as tropical rainforests, open oceans or African
grasslands, a common language is needed. This language includes the terms trophic level, food
chain and food web.
Science for the New Zealand Curriculum Year 11
© Donald Reid, Geoffrey Groves, Colin Price, Ian Tennant 2011
Published by Cambridge University Press www.nzscience.co.nz www.cambridge.edu.au
Sheet 12.1 Revision Ecological terminology
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Trophic levels
A trophic level means a feeding level. Plants are in trophic level 1 because they are the first
to use the sun’s energy. Anything that eats something from trophic level 1 is said to be in
trophic level 2. Creatures that consume organisms in trophic level 2 will be in trophic level 3
and so on. See Figure 2.14 on page 36. When organisms eat a range of food they can belong
in several trophic levels.
Food chains
Food chains are a single, one-way path showing what organisms are feeding on. Food chains
are drawn as diagrams, with arrows between different species. The arrows should always
point to the organism that is eating (not to the one being eaten) so they show the direction
energy is flowing in. There are usually only three to four steps in a food chain, because
energy is lost at every step, so the energy available gets less and less.
trophic level Feeding level in a food chain
food chain The unidirectional flow of food or energy from producers to consumers
food web A set of interconnected food chains
Figure 2.11: A food chain
Food webs
A food web is a collection of interconnecting food chains. Food webs are useful for showing
how species compete. Like food chains, food webs are short due to continuous energy loss.
Science for the New Zealand Curriculum Year 11
© Donald Reid, Geoffrey Groves, Colin Price, Ian Tennant 2011
Published by Cambridge University Press www.nzscience.co.nz www.cambridge.edu.au
Sheet 12.1 Revision Ecological terminology
Figure 2.13: A food web
Science for the New Zealand Curriculum Year 11
© Donald Reid, Geoffrey Groves, Colin Price, Ian Tennant 2011
Published by Cambridge University Press www.nzscience.co.nz www.cambridge.edu.au
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