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Discover the diversity of Cape Town's colourful nudibranchs
02 November 2020
By Danel Wentzel
What are nudibranchs?
Small, colourful and varied, nudibranchs are many diver’s favourite subject matter. Nudibranchs as a group can be found across the world, but most species are endemic to an area.
Nudibranchs are members of the phylum Mollusca, which is derived from the Latin “mollus”, meaning soft-bodied. A common characteristic to all members of this group. They are part of the order Opisthobranchia which include all the sea slugs. All nudibranchs are sea slugs, but not all sea slugs are nudibranchs – they fall in their own order, Nudibranchia.
The word nudibranch is derived from Latin and means “naked gill” – for the reason that their gills are on the outside of their bodies. The nudibranchs are the only subgroup to have its own subgroup, which contain the 4 suborders Doridina, Dendronotina, Aeolidina and a group that does not fit into the previous three, the Arminia.
Now that we know what nudibranchs are - let us have a look at some familiar little faces that you may have encountered on your dives in Cape Town.
Doridina.
Contains more species than the rest combined. Frequently spotted due to their relatively large size and typically flamboyant colours. All Dorids display conspicuous gills and for most the gill structure forms rosettes or circles around the anus.
Cape Dorid
Hypselodoris capensis
Twin crown
Polycera sp.
Fiery Nudibranch
Okenia amoenula
Black nudibranch
Tambja capensis
Ghost nudibranch
Lecithophorus capensis
Orange clubbed
Limacia lucida (previously L. clavigera)
Dendrodorotina.
Typically long and tapered with gills forming a series of appendages. The groups rhinophores are generally fluted or cup-shaped.
Cowled nudibranch
Melibe rosea
Arminia.
A catch-all for species that do not fit into other suborders. An oral veil, also known as a velum, on the head is the only obvious characteristic that Arminids have in common.
Frilled nudibranch
Leminda millecra
Gas flame
Bonisa nakaza
Cape silvertip
Janolus capensis
Aeolidina.
Members typically have long tapering bodies, a pair of cephala tentacles on their heads, and clusters or rows of cerata extending down their backs.
Four-colour
Godiva quadricolor
Purple lady
Flabellina funeka
Coral nudibranch
Phyllodesmium horridus
Orange - eyed
Cratena capensis
There are about 80 unique species of Opisthobranchs in False Bay and the Cape Peninsula of which 67 are nudibranchs. There are plenty of little critters to find underneath the canopy of Cape Town's kelp forests and will keep even the most veteraned diver busy for many dives to come.
We have put together a beautiful PDF filled with all our nudibranch photos for you to use as a reference after your dives. Just download it to your phone for safe keeping.
If you want to have your own comprehensive field guide we recommend the local book by Guido Zsilavecz called Nudibranchs of the Cape Peninsula and False Bay which you can order directly from him here.
References.
All images are copyright of Danel Wentzel.
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