Environmental position

Terms used to describe the position of an organism relative to its substratum (e.g. rocky or sedimentary seabed) or the water column

Substratum (surface) - position relative the surface of hard or soft substratum

Environmental position Definition
Epilithic Growing on the surface of rock or other hard inorganic substrata.
Epibenthic Living on the surface of the seabed.
Epifaunal An animal living on the surface of the substratum (McLeod, 1996).
Epifloral A plant living on the surface of the substratum (McLeod, 1996).
Epiphytic Growing on the surface of a living plant but not parasitic upon it (McLeod, 1996).
Epizoic Growing or living on the exterior of a living animal but not parasitic upon it.
Epipelic An organism that moves over the surface of sediment or living at the sediment / water interface

Substratum (body)- position relative to the body of the hard or soft substratum.

Environmental position Definition
Infaunal Benthic animals which live within the seabed.
Interstitial Relating to the system of cavities and channels formed by the spaces between grains in a sediment (interstitial space).
Lithotomous Relating to an organism that burrows into rock (Lincoln et al., 1998).
Endozoic Living within the body of an animal (Lincoln et al., 1998).
Endophytic A plant living within another plant (Lincoln et al., 1998).

Water column - position within the water column

Environmental position Definition
Pleustonic Living permanently at the water surface due to their own buoyancy, normally positioned partly in the water and partly in the air.
Neustonic Living on or under the surface film of open water.
Pelagic Inhabiting the open waters of the sea or ocean, excluding the bottom layers (Lincoln et al., 1998).
Demersal Living at or near the bottom of a sea or lake, but having the capacity for active swimming (from Lincoln et al., 1998).
Hyperbenthic Living above but close to the substratum (from Lincoln et al., 1998).


  1. Lincoln, R.J., Boxshall, G.A. & Clark, P.F., 1998. Dictionary of ecology, evolution and systematics. 2nd ed. Cambridge: Cambridge University Press.
  2. McLeod, C.R., 1996. Glossary of marine ecological terms, acronyms and abbreviations used in MNCR work. In: Marine Nature Conservation Review: Rationale and methods, (ed. K. Hiscock), pp 93-117. Peterborough: Joint Nature Conservation Committee.