Doridoidea
This is the largest nudibranch sub order containing a wide variation of
body types. The general body shape is circular (ellipsoid) or elongated.
The thick fleshy mantle has a skirt extending over the side of the body.
Two antennae (rhinophores) often with numerous folds ridges (lamellae)
protrude from the head (anteriorly). They are used to smell (chemosensors)
each other or locate food. Towards the back (posteriorly) are the gills,
delicate and flower like, hence the name nudibranch (naked gills). The
anus is found inside the gill plumes.
Dorids feed on sponges, bryozoans. polychaete worms, ascidians and other
opisthobranchs. The digestive gland that is a single mass (holohepatic).
They can be brightly coloured and obvious (aposematic) or drab
and well camouflaged (cryptic). The red and pink species are especially
cryptic below 10 metres as the red has been filtered out of the light spectrum.
The colour patterns of particular groups have been studied and a theory
is that many species mimic each other.
Many dorids have toxins in their mantle glands taken from food source,
which they secrete when disturbed. Species without this protection are
believed to mimic toxic relatives colour patterns.
Another view is that since light cannot penetrate far into water the
colours actually assist the animal to blend into the surroundings. Size
ranges from 1-30cm.
The two major super families are:
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1. The Phanerobranch dorids (Anadoridoidea) retract their gills into a tight group on the
back. The gills do not retract into a branchial pocket. Size ranges from
10 cm down to 5 mm.
Includes the families: Corambidae, Goniodoridae,
Onchidorididae, Polyceridae, Gymnodorididae, Aegiretidae and Vayssiereidae.
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2. The Cryptobranch dorids (Eudoridoidea) can fully retract their gills into a branchial
pocket. All are sponge feeders and slow moving.
Includes the families:
Hexabranchidae,
Dorididae, Chromodorididae, Dendrodorididae and Phyllidiidae.
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