Description Electra posidoniae is a Bryozoan that forms colonies of zooids. Each zooid will reach up to about 0.5mm in length. The frontal membrane is oval shaped and bordered by spines, the mid proximal spine often being considerably longer than the rest. One third of the frontal surface is heavily calcified with very few pores (1).
Life Cycle E. posidoniae is capable of both asexual and sexual reproduction. Asexual reproduction is the primary way in which colony expansion occurs with new zooids budding off as the colony grows. If part of the colony breaks off this piece has the potential to grow into a new colony through this reproductive method. As E. posidoniae is hermaphroditic, when reproducing sexually the sperm and eggs are produced by the same individual. Fertilised eggs divide and develop into free swimming larvae which will later settle and metamorphose into a new zooid when they come across a suitable substrate (Posidonia). This zooid will then become the basis for growth of a new colony (2).
Habitat E. posidoniae is an epiphyte on the leaves of the sea grass Posidonia (2).
Distribution It can be found throughout the Mediterranean wherever Posidonia sea grass occurs (1).
Food E. posidoniae feeds on planktonic micro-organisms which it filters from the water column using ciliated feeding tentacles (lophophore) (2).
Conservation status Not listed under the IUCN Redlist (3).
References Description written by Angus Smith (2009) (1) Hayward, P., Nelson-Smith, T. & Shields, C., 1996. Collins Pocket Guide – Sea Shore of Britain and Europe. London: Harper Collins Publisher Ltd. (2) Buschbaum, R. et al, 1987. Animals without backbones (3rd edition). Chicago: University of Chicago Press (3) IUCN 2009. IUCN Red List of Threatened Species. Version 2009.1. <www.iucnredlist.org>. Downloaded on 10 September 2009.