Pleurobranchus forskalii
(Ruppell & Leuckart, 1828)

Family: Pleurobranchidae


Throughout the tropical Indo-West Pacific.


UPPER RIGHT: (upper photo)- Dorsal view of pale colour form, Mbudya Is, off Kunduchi Beach, Dar es Salaam, Tanzania, 80mm long,, June 1973. (Lower photo)- Right side view showing large gill, Fumba, Zanzibar, Tanzania, July 1971.
LOWER LEFT: Colour variation in animals from large population in sea-grass beds, Fumba, Zanzibar, Tanzania, July 1971.
LOWER RIGHT: Koumac, New Caledonia, October 1993.
PHOTOS: Bill Rudman.

This relatively large pleurobranch is often found in quite large populations in shallow lagoons, reef crests and pools and sea grass beds. It usually grows to about 10cm long but can grow to over 30cm. I know of no feeding reports for this species, but other species of Pleurobranchus are reported to feed on ascidians. While I was in Tanzania, a colleague, asked me if I had any idea of the identity of a pile of about 40 strange chitinous plates he had found in the stomach of a turtle. They were easily identifiable as the jaw plates of Pleurobranchus forskalii. As these photos show, this species is very variable in colour. The light brown colour form was originally described as a distinct species, Pleurobranchus semperi but anatomically it is identical to the dark purple-brown animals originally described as P. forskalii

In the above photo you can see the large gill, which as in all notaspids, is found on the right side of the body in the gap between the mantle and the foot. This is why some authors use the common name "Side-gilled Slugs" for this group of opisthobranchs.

• Ruppell, E. & Leuckart, F.S. (1828). Neue wirbellose Thiere des Rothen Meeres. Atlas zu der Reise im nordlichen Afrika von Eduard Ruppell: 1-22.

Authorship details
Rudman, W.B., 1999 (March 9) Pleurobranchus forskalii (Ruppell & Leuckart, 1828). [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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