Seasonal Changes in Dispersion Within an Aggregation of the Anemone, Actinia Equina, With a Reappraisal of the Role of Intraspecific Aggression

Abstract

Although intraspecific aggression in the anemone, Actinia equina L. has been behaviourally well characterized in laboratory-based studies (Bonnin, 1964; Brace & Pavey, 1978; Brace, Pavey & Quicke, 1979), both its incidence and functional role on the shore have remained obscure. Since A. equina broods young, which are produced asexually (Carter & Thorp, 1979; Gashout & Ormond, 1979; Orr, Thorpe & Carter, 1982) and which appear best suited to local dispersal, we have previously postulated that aggression is likely to be primarily directed towards maintaining ‘territorial’ space for settling syngeneic offspring (Quicke & Brace, 1983; Brace & Quicke, 1985). As such, this postulated role is functionally analogous to that provided by aggression in the clonally reproducing anemone, Anthopleura elegantissima Brandt, in which it serves to maintain the integrity of clonal boundaries (Francis, 1973, 1976), thereby presumably also facilitating the competitive expansion of those boundaries. Work by Ayre (1983) on the Australian anemone, Actinia tenebrosa Farquhar appears to support this contention, for both local settlement and genotypic clustering were detected within aggregations.