This species has been observed on Mayotte and Madagascar Islands
Order : Nudibranchia
Suborder : Euctenidiacea
Superfamily : Doridoidea
Family : Chromodorididae
Distribution :
Tropical Indo-West Pacific
Maximal size : 150 mm
Abundance :
Species characteristics : It has a hard, almost rigid body with a long tapering foot and highly branched gills set between the three rounded triangular lobes of the mantle, one to each side and one arching over the gill, posteriorly
The mantle is usually blotchy red with bright yellow spots The purple border to the mantle and foot is usually an unbroken line |
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Showing species characteristics... |
Photo Alain-Benoît Rassat
Madagascar, Nosy bé, banc corail noir, 25 m, 18 July 2013, size : 150 mm
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See more about : Sightening and mating periods
Remarks :
Identification confirmed by Nathalie Yonow
Synonymous (according worms) :
- Ceratosoma berghi, Rochebrune, 1895 - Ceratosoma lixi, Rochebrune, 1894
- Ceratosoma caledonicum, Fisher, 1876 - Doris trifida, J. E. Gray, 1850
- Ceratosoma corallinum, Odhner, 1917 - Doris trilobata , J. E. Gray, 1827
- Ceratosoma cornigerum, Adams & Reeve, 1850 - Polycera cornigera, Adams & Reeve in Adams, 1848
- Ceratosoma gibbosum, Rochebrune, 1894
Bibliographic data :
There is a distinct ridge around all the mantle edge
The lamellate rhinophores are tall. They are usually brown with yellow flecks on the lamellae and a blue apex
The numerous long bushy gills form a circle around the anus. They are translucent white with red streaks up both axes
The colour pattern is complicated and very variable :
- The mantle purple border can be unbroken or broken. In some specimen
there is a continuous purple line which breaks up at the “neck” between
the "cephalic expension" around the head and the "lateral expansion" in front of the gills
- In some specimens, the "horn" is spotted with larger red spots on both sides
- Body red with yellow, orange or
reddish
spots.
In some specimens, each ring is situated on a lighter, sometimes white background area. Some specimens haven't any spots...
- The background colour can vary from orange-red to brown
- Sometimes there is a violet edge around the gills and rhinophore pockets
It has a long recurved dorsal "horn'" which acts as a defensive lure attracting potential predators to the part of the animal which contains most of the distasteful chemicals stored from their food.
In species of Ceratosoma the oral tube is brightly coloured rather than colourless as in species of Chromodoris.
It feeds on a bluish sponge colony, a dysideid sponge, perhaps a species of Euryspongia
We have is indirect evidence of the feeding sponge from chemists (Mollo, 2005) who have found molecules characteristic of dysideid sponges in the mantle glands of C. trilobatum.
The egg mass is orange.
This species has 1 dorsal lobe and 1 lateral mantle lobe on each side (= 3 lobes) which makes it C. trilobatum (tri = 3; lobatum = lobes).
The two common tropical species of Ceratosoma , C. tenue and C. trilobatum, are variable in colour, and as both can have very similar colour patterns, considerable confusion has occurred in the past over the identity of specimens.
But these two similar species have some differences.
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Ceratosoma trilobatum |
Ceratosoma tenue |
Mantle lobes |
It is characterised by having only one large lateral lobe on each side of the body, just anterior to the gills |
It is characterised by the three mantle lobes on each side of the body |
Purple border |
The purple border to the mantle and foot is usually an unbroken line |
The purple border to the mantle and foot is always a dotted line |
Gills and rhinophores pockets |
The gills and rhinophores pockets bear purple around its margin |
The gills and rhinophores pockets do not bear purple around its margin |
References :
Bill Rudman Seaslug site : Sea Slug Forum : Ceratosoma trilobatum
Nudipixel Ceratosoma trilobatum
Publications :
Gray, J.E. 1827. Mollusca, pl. 3. In : E. Smedley (Ed.). Encyclopaedia Metropolitana; or, Universal dictionary of knowledge. London
Mollo, E., Gavagnin, M., Carbone, M., Guo, Y.-W., and Cimino, G. (2005) Chemical studies on Indopacific Ceratosoma nudibranchs illuminate the protective role of the dorsal horn. Chemoecology 15: 31-36
Rudman, W.B. (1984) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: a review of the genera. Zoological Journal of the Linnean Society 81 : 115-273
Rudman, W.B. (1988b) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: the genus Ceratosoma J.E. Gray. Zoological Journal of the Linnean Society, 93(2) : 133-185
Rudman, W.B. (1991) Purpose in Pattern: The evolution of colour in chromodorid nudibranchs. Journal of Molluscan Studies, 57 (T.E.Thompson Memorial Issue) : 5-21
Other photos of Ceratosoma trilobatum :
Fabrice Schubert
Mayotte, "Mhila", 15 m, 21 March 2010, size : 15 mm
It is a juvenile (15 mm) form with some interesting characteristics :
- A pale mantle coloration (a)
- A broken purple border on the mantle (b) and the foot (c)
- Some red spots (d) on the "horn"
- Yellow-orange rhinophores (e) with very pale blue (
almost
white) apex (f)
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