Gymnodoris ceylonica burrowing in sand at Puri Jati on the north coast of Bali
Gymnodoris ceylonica (Kelaart, 1858)
One of the largest species of Gymnodoris, it reaches over 120mm in length. It is easily recognized by its white body with large red spots and a yellow-orange marginal line on the foot and on the rhinophores.
All gymnodorids are voracious slugivores, feeding on any opisthobranch they can track down. While Lawrence was shooting these pictures he found several burrowing (photo at left) into the sandy sediment, likely following the slime trail of a burrowing species of slug. These guys are so nasty, they are even cannibalistic. Note Lawrence's photo of the small Gymnodoris biting the much large G. ceylonica. Recall that these slugs do not have eyes, so when they catch up with prey critters they have no idea how large lunch might be. See page 109 in my Nudibranch Behavior book for other examples of appetite imbalance.
One last shot shows a mating pair . I would not be surprised if one member of the pair turns around and eats the other after this consensual activity. This kind of cannibalism is common in this genus.
This species occurs throughout the Indo-pacific, but Lawrence's specimens here may be the first records from Thailand.
Lawrence is a newspaper journalist based in Bangkok, Thailand. He escapes the office as often as he can to go diving in the rich waters of the Indo-Pacific but his regular dive sites are just down the road along the Gulf of Thailand and the Andaman Sea coast. Lawrence uses a Nikon D200 with a 60-mm or 105-mm macro lens in a Nexus housing together with a pair of Inon Z240 strobes and several wet lenses for the really small stuff.
Send Lawrence mail at firstname.lastname@example.org