Site author Richard Steane
The BioTopics website gives access to interactive resource material, developed to support the learning and teaching of Biology at a variety of levels.


Living organisms need certain things in order to live.

Animals need air to breathe as a source of oxygen, food to eat to provide energy, certain minerals to provide some of the body's needs and water to drink. These can be called resources. In the wild, they need a certain amount of space in which to find these things, and also for shelter, such as roosting at night, and opportunities to find a mate.

Plants also need resources, although some are rather different than animals: They need air as a source of carbon dioxide when they are photosynthesising in the daytime, and they do not need to get the same sort of food that animals search for - they can make it themselves by the process of photosynthesis. They need light as an energy source for this process. Plants need minerals (some different than animals), and water. They also need space in which they can get enough light, and water containing minerals. Some of their life processes may need an input from animals, so all of these things could be looked upon as resources.

Unfortunately there are not enough of these resources to go round. As a result of this scarcity of resources, there is competition between living organisms in their environment.
What resources are these animals competing for?
(mouseover for answers!)
[Click for slightly larger picture as a separate page]

pics/Zebra.jpg pics/200410815336186zebra and oryx.jpg
pics/kingpenguincolony.jpg pics/Elephant seals Mating04.jpg

Similarly, plants also compete for resources.
What do you think these plants are competing for?
(mouseover for answers!)
[Click for slightly larger picture as a separate page]

rain forest plants - especially tree ferns cacti and other desert plants
Trees in a suburban area, showing dry brown spaces underneath red Jewel Plant - a sort of sundew (carnivorous plant)
bee pollinating flower pics/birds_bees_bats_2.jpg
monkey up a tree eating fruit a goosegrass burr


The resources that animals mainly compete for are food, water, space to live and breed in (including access to food and water), and for access to mates.

Plants also compete for water and living space (including access to light, and minerals in soil), and sometimes for the attention of certain animals for pollination and occasionally other animals for seed dispersal.

Competition is more noticeable in the case of animals than in plants, but it still exists nevertheless. You just don't see plants fighting or hear them driving others away!

Competition between members of different species is called inter-species competition.
If the different species compete with one another directly for the same resources, this may have some influence on the size of populations and their distribution.

On the other hand, if populations of different species exist together in an environment, they presumably do not compete for exactly the same resources, as each species seems to be specialised for slightly different aspects of their general environment.

Competition between different members of the same species is called intra-species competition.
Different members of the same species obviously compete for the same resources, because they share the same requirements and are also equipped with similar bodies. This is responsible for a lot of territorial behaviour and also for behaviour modifications which enable organisms to exist together reasonably harmoniously as they raise young.

It is often noticed that the most successful animals and plants in an area seem to be well adapted to their environment. It would be wrong to think that these organisms decided to do things in a certain way! Generally any specialisations have arisen over a long time, and biologists normally explain this in terms of evolution rather than a quick or guided process.

Nevertheless, some very impressive features can be seen in certain environments, and each part of Planet Earth has its own native flora and fauna (plants and animals). It is interesting to try and identify specialisations in certain areas which seem to deal with competition for resources. e.g. African plains, Arctic ice, deserts, woodland, tropical seas

Some thoughts

Animals all need oxygen (so do plants).
Plants need carbon dioxide for photosynthesis.
Can you think of a way in which animals compete for oxygen?
Can you think of a way in which plants compete for carbon dioxide?
>Nor can I !  
Any ideas why ?

>Probably because they are gases, and hard to monopolise.

Photo credits

You might even want to send me some better photos from your holidays!

Wildebeest and Zebra

Zebra and oryx

Elephant seals

King penguin colony

Tree ferns


Suburban trees in Sydney

Red Jewel Plant



Monkey eating fruit
check out the list of fruits!

Goosegrass burr

Zebra, wildebeest

Grey squirrels

Red squirrels


Great crested grebes

Web references

Red squirrels (in Scotland) Scottish National Heritage Information and Advsiory (sic) Note Number 70, January 1997

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