Mantle flapping in Chromodoris
A,B. Chromodoris kuniei (A) and Chromodoris geminus (B) showing 'mantle-flapping' in which the whole of the mantle edge rises simultaneously and then falls simultaneously. Photos: Bill Rudman.
C,D. Chromodoris hintuanensis (C) and Chromodoris geometrica (D) showing 'mantle-flapping' in which only the front of the mantle edge rises falls in a rhythmic wave. Photos: Mary Jane Adams (C), Erwin Koehler (D).
Within the Chromodorididae there are a number of interesting behavioural traits which are found amongst certain groups of species. Species of Risbecia exhibit 'trailing' where two animals will pair up with one following close behind the other. Many species of Thorunna and some species of Noumea rhythmically wave their gills as they crawl along.
Amongst species of Chromodoris there are two groups of species which flap their mantles in a rhythmic way. Chromodoris kuniei, Chromodoris geminus and Chromodoris tritos show 'mantle-flapping' in which the whole of the mantle edge rises simultaneously and then falls simultaneously. All species are similarly coloured and appear to form a group of allopatric sibling species [each with non-overlapping geographic distributions]. Another species pair with this type of mantle-flapping are Chromodoris coi, from the western Pacific and its sibling species, Chromodoris gleniei from the western Indian Ocean. There is a good photo of C. coi mantle-flapping on the C. coi page.
Chromodoris hintuanensis and Chromodoris geometrica show a different type of 'mantle-flapping' in which only the front of the mantle edge rises and falls in a rhythmic wave. It seems the species that belong to this behavioural group also have a bright purple colouration on the underside of the anterior mantle.
At this stage we have no idea what the 'purpose' is, if any, for this type of behaviour.
If anyone comes across this or any other peculiar behaviour pattern I would very much like to hear of it so we can record it on the Forum and alert others to look out for similar happenings.
Bill Rudman.Authorship details
Rudman, W.B., 2000 (June 13) Mantle flapping in Chromodoris. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/mantflap