When two species in the same community require the same resources as
food, shelter, light etc., which are in short supply in relation to the number seeking it,
or interact in such a way that it affects their growth and survival, they are said to be in
competition with each other. on the rocky sea coasts of Scotland, the larger and
competitively superior barnacle Balanus dominates the intertidal area, and excludes
the smaller barnacle Chathamalus from that zone.