This sub-division of biology deals with the interaction between living organisms and their environments, as well the relationships between different species. It focuses upon life cycles and adaptations of these organisms and their dissemination within a particular type of environment.

Ecology is associated with environmental studies, eco issues and natural history but these are by no means exclusive. There are close links with other fields such as genetics, physiology and evolutionary biology.

Ecologists study relationships between all forms of life and their environments. Examples of living organisms include:

  • Human beings
  • Animals
  • Plants
  • Marine life
  • Fungi
  • Micro-organisms

Examples of appropriate environments include:

  • Oceans
  • Volcanoes
  • Coastal regions
  • Soil
  • Atmosphere
  • Glaciers

They are particularly interested in how living things are organised within an environment and the transportation of energy and other materials in communities.


Whilst ecology is the name given to the scientific study, the term ecosystem is often used when discussing the relationship of an organism to its habitat.

There are various types of ecosystems which are comprised of a biological community within a physical environment. Examples of these include an aquatic ecosystem such as a lake, river or ocean and a terrestrial or land ecosystem such as grassland.

Human beings are part of an ecosystem, for example cities which contain large numbers of people in a tightly defined area or within the larger conurbations.  

The difference between these and other types of ecosystems is that human ecosystems are man made.

Hawaiian ecology

Hawaii is rich in ecological habitats which feature a wide variety of coastlines, marine life and land ecosystems such as tropical rain forests.


The coastal areas consist of sandy beaches and rocky shorelines, some of which are characterised by steep or gently sloping cliffs. The areas with steep cliffs have little access to the ocean whereas those with gently sloping precipices contain attractive looking tide pools.

Tide pools

These tide pools contain an abundance of marine life such as hermit crabs, anemones, barnacles and mussels. They also feature the Hawaiian pencil urchin and the potentially lethal sea urchin.

Coral reefs

Coral reefs are another feature of the Hawaiian coastline although these are less dense and widespread compared to other established reefs which is due to its close proximity to the border. Brightly coloured fish such as the squirrel and reef fish live are found in these waters along with the marine turtle.

Terrestrial areas

Closer inland the moisture laden air driven by the trade winds has resulted in areas of fertile vegetation, tropical rain forests and waterfalls which are home to numerous species of animals and plants. These are located on the eastern side of the islands.

Conversely, the western side of the Hawaiian Islands is a dry, arid area which features lava deserts, craters and volcanoes. The absence of rainfall means that there is little vegetation although there is a particular species of plant know as 'Silversword' which is endemic to these islands.