Kerama Islands, Okinawa, Japan. Size approx: 17mm., Depth: 2m., 7 Jul 2002. Photo: Jun Imamoto
A very flattened Sea Hare, in which the parapodia are reduced and fused, exept for a small postero-dorsal opening into the mantle cavity, which covered by a pair of small rounded flaps. The body is translucent with a pattern of broad, fairly indistinct, white longitudinal bands along the length of the body. In some specimens the white bands are broken into white patches. Scattered over the body are slightly raised papillate tubercles with scattered brown and opaque white specks. The whole of the body is covered with brown specks, which appear to be embedded in the skin as they are almost completely obscured by the white banding. There is a thin opaque white line along the edge of each oral tentacle, and this continues along the right side, beside the sperm groove, until it reaches the mantle cavity. First described from the Mediterranean, this species is known from records throughout the warm waters of the world. The photo here from Japan looks identical to a photo in Ocana, (2000) from the Straits of Gibraltar. Grows to about 40mm long.
• Ortea, J.A. & Martínez, E. (1991) El Orden Anaspidea (Mollusca: Opisthobranchia) en las Islas Canarias. Rev. Acad. Canar. Cienc., 3(4): 87-107.
• Martinez, E. (1996) On Petalifera petalifera (Rang, 1928) (Gastropoda: Opisthobranchia): new anatomical and geographical data. Journal of Molluscan Studies, 62: 243-250.
• Rang, S. (1828) Histoire naturelle des Aplysiens, premiere famille de l'ordre des Tectibranches. In: Histoire naturelle Generale et particuliere des Mollusques. Firmin Didot, Paris, 84pp. Pls. 1-24.
Rudman, W.B., 2003 (April 27) Petalifera petalifera_arch (Rang, 1828). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/petapeta_arch