CONICET | Buscador de Institutos y Recursos Humanos

Sea pens are a particular group of octocorals that could be found in all the world´s oceans, from tropical to polar regions and fromintertidal to more than 6100 m. In deep seas, pennatulaceans could be patchily distributed in moderately high energy environments,mostly sea mounts, slopes and along bases of ridges, and may be important members of coral gardens occurring in dense stands. Inareas where the consolidated substrate is generally scarce, the structural three-dimensionality of the octocorals serves as a biogenicsubstrate. Compared to other cnidarians, there have been relatively few records of associated species with sea pens. In this study, wereport for the first time the association between Anthoptilum grandiflorum and Halipteris africana with the sea anemone Hormathiapectinata in Argentine slope waters between 400-1000 m depth. Some small individuals of H. pectinata were observed settled on therachis (soft tissue) of A. grandiflorum while adult specimens were strongly attached to the axis of the octocorals. In some of the observedspecimens, the lack of soft tissue underneath adult sea anemones is consequence of its settlement. Then, can be hypothesized that thesea anemone larva colonize the dorsal part of the rachis (soft tissue) of the sea pens (free of polyps) and at the time it develops, itdegrades the coenenchyme live tissue to finally attached to the central axis. In that sense the sea anemones benefit with hard surface toattach in a muddy seafloor. Loss of octocoral tissue and the instability of the colony caused by the presence of the sea anemones cancharacterize this association as parasitism. The association here reported represents the second report of the world (the first wasStephanauge nexilis on Halipteris finmarchica in Canadian waters) and the first one for the South Atlantic Ocean of a sea anemone with apennatulacean.