Add to collection
  • + Create new collection
  • This resource provides explanations of the key concepts encountered when exploring life in the sea – the ‘basics’ that every student should understand.


    Adaptation is an evolutionary process whereby an organism becomes increasingly well suited to living in a particular habitat. Adaptation is also a term used to describe a particular feature of an organism that helps them to live in that habitat.


    The range of species found in a particular region. It is generally thought that the more species that exist, the higher the biodiversity, the more likely it is that an ecosystem will survive episodes of change in the environment.

    Canary in the coalmine

    For many years, coalminers brought canaries into the mines with them. The canaries were more sensitive than people to the presence of toxic gases, and when they got sick or died, this acted as an early warning signal for the miners. The term is now commonly used to refer to organisms that are bioindicators – species that can be used to monitor the health of an environment or ecosystem.

    Chemical markers

    In ecology, the term chemical marker refers to something in the chemical composition of an organism that can tell us something about the environmental conditions, i.e. food availability or water chemistry during the life of an organism. Examples of chemical markers are stable isotopes in fish and bivalves, and plant pigments found in sediment cores. Chemical markers are sometimes also called chemical ‘fingerprints’ or ‘signatures’.


    The process of ordering living things into a system that allows scientists to identify them. Modern science uses the Linnaean system of classification where organisms are grouped based on what species they are most closely related to.


    All the living organisms and their interactions with the physical features within a given area.

    Food web

    Food webs illustrate the networks of feeding relationships between organisms that live in a particular area. All food webs are made up of producers, consumers and decomposers.


    The area in which an organism lives and breeds.

    Keystone species

    A species that has a greater impact on the community of organisms in an ecosystem than you would expect in relation to its abundance. The removal of a keystone species from an ecosystem results in a major change, in the same way that removing a keystone from an arch or bridge could cause the structure to collapse.

    Land use change

    When there has been human modification of the natural environment, for example, changing forestry to pasture land for farming or increased urbanisation.

    Ocean acidification

    The term used to describe the reduction in ocean pH due to higher levels of dissolved carbon dioxide.

    Water column

    The term used to describe the vertical section of water between the ocean floor and the surface. The water column is divided into a maximum of 5 layers, depending on the depth.

      Published 3 November 2016 Referencing Hub articles
          Go to full glossary
          Download all