Tylodina perversa is a small sea slug that can grow up to 35mm in length. It has a bright yellow body and can be recognized by its conical external shell, similar to that of a limpet in appearance and covered in a layer of periostracum. The head is frontally flattened with short antero-laterally positioned oral tentacles and long dorso-lateral rhinopores (1).
T. perversa will often burrow into and live within the sponge upon which it is feeding (2).
T. perversa are hermaphroditic so are able to produce both sperm and eggs (3).
T. perversa can be found in shallow sublittoral areas on rocky coasts (1).
It is distributed throughout the Mediterranean (1).
T. perversa feeds upon sponges, specifically on Aplysina aerophoba and actually derives its colour from the sponges yellow pigment “uranidine” (2).
Not listed under the IUCN Redlist (4).
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) Thoms C., Ebel R., Hentschel U., Proksch P., (2003), Sequestration of Dietary Alkaloids by the Spongivorous Marine Mollusc Tylodina perversa. Journal of Biosciences, 58c (5/6): 426-432
(3) Club d’immersio biologia, http://www.cibsub.com/bioespecie.php?idg=27921. Accessed 09/09/2009
(4) IUCN 2009. IUCN Red List of Threatened Species. Version 2009.1. <www.iucnredlist.org>. Downloaded on 09 September 2009.