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Patterns of Life Within the Habitat

Unlike plant communities, habitats rarely have clear boundaries. But animals favour the edges of those communities. It is there that the vegetarian finds a varied food supply and usually one side is more dense, providing, effective shelter. Each species has different abilities to survive and these attributes of shape, colour, speed and behaviour restrict the animal.

The coastal rock platform shows this very well. This habitat is a mosaic of smaller units which make specific demands on an animal. There are four zones which are variously affected by sea water: offshore fully submerged edge; a strip affected by tides; a strip which ranges from wet to dry because of splash and which becomes caked with salt and at times drenched in rainwater; and a zone which while salty is normally dry unless rained on or splashed during high storms.

Bony fish and marine invertebrates are best adapted to full submergence, while cormorants and dolphins are able to make a life in the water only so long as they can breathe air. In the same way some marine invertebrates move over the tidal wet areas by carrying a water supply with them. Rock pools on the platform are small marine habitats.

The course of a river from source to sea shows how a riverine habitat is a chain of slightly differing habitats. High in the system here are hard rocky beds and those with boulders or pebbles which provide quite different conditions to the sandy or muddy beds and banks lower down the system. The speed of flow from mountain to sea slows down, placing differing demands on the animals and plants living there. While Rakali (water rats) make nests among rocks, in logs and in soft banks, the platypus needs soft banks for nest building even though water temperature and food supply are adequate in the upper river system. Rakali (water rats) are more adaptable to habitat characteristics and changes than platypus.

Can we think then of patterns in the habitat? To successfully manage plant and animal habitat, we need to understand a lot about the biology, ecology and habitat needs of each species.