Twin-crowned nudibranch
Encyclopedia
The twin-crowned nudibranch, Polycera sp., as designated by Gosliner, 1987, is a species
of dorid
nudibranch
. It is a marine
gastropod mollusc in the family
Polyceridae
. As at November 2009, it remained undescribed by science.
in False Bay
and off Durban
in 2-30 m.
, though these can be absent. The head has six yellow projections. The gill
s and rhinophore
s are black, and may be spotted with yellow. There are raised yellow spots on the mid-dorsal region. Alongside the gills are two or three pairs of yellow projections, which differentiate the animal from the crowned nudibranch
and the fourline nudibranch
. The animal may reach 30 mm in total length.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of dorid
Doridacea
Doridacea is a taxonomic grouping of dorid nudibranchs, shell-less marine gastropod mollusks. included in the clade Euctenidiacea of the clade Nudibranchia.- Taxonomy :*Superfamily Doridoidea**Family Dorididae**Family Actinocyclidae...
nudibranch
Nudibranch
A nudibranch is a member of what is now a taxonomic clade, and what was previously a suborder, of soft-bodied, marine gastropod mollusks which shed their shell after their larval stage. They are noted for their often extraordinary colors and striking forms...
. It is a marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
gastropod mollusc in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Polyceridae
Polyceridae
Polyceridae is a taxonomic family of sea slugs, dorid nudibranchs, marine gastropod mollusks within the Superfamily Polyceroidea.- Taxonomy :...
. As at November 2009, it remained undescribed by science.
Distribution
This species has been found off the southern African coast off the Cape PeninsulaCape Peninsula
The Cape Peninsula is a generally rocky peninsula that juts out for 75 km into the Atlantic Ocean at the south-western extremity of the African continent. At the southern end of the peninsula are Cape Point and the Cape of Good Hope...
in False Bay
False Bay
False Bay is a body of water defined by Cape Hangklip and the Cape Peninsula in the extreme South-West of South Africa.- Description and location :...
and off Durban
Durban
Durban is the largest city in the South African province of KwaZulu-Natal and the third largest city in South Africa. It forms part of the eThekwini metropolitan municipality. Durban is famous for being the busiest port in South Africa. It is also seen as one of the major centres of tourism...
in 2-30 m.
Description
The twin-crowned nudibranch is a smooth-bodied variably coloured nudibranch. The ground colour is white or grey and there are usually black, yellow or orange stripes longitudinally along the notumNotum
The notum is the dorsal portion of an insect's thoracic segment. It is typically a single large sclerite. It can be further divided into the alinotum which bears the wings and the postnotum which bears the phragma....
, though these can be absent. The head has six yellow projections. The gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s and rhinophore
Rhinophore
A rhinophore is one of a pair of club-shaped structures which are the most prominent part of the external head anatomy of a group of sea slugs, marine gastropod opisthobranch mollusks in the order Nudibranchia, the nudibranchs, specifically the dorid nudibranchs.- Etymology :The name relates to the...
s are black, and may be spotted with yellow. There are raised yellow spots on the mid-dorsal region. Alongside the gills are two or three pairs of yellow projections, which differentiate the animal from the crowned nudibranch
Crowned nudibranch
The crowned nudibranch, Polycera capensis, is a species of dorid nudibranch. It is a marine gastropod mollusc in the family Polyceridae.-Distribution:...
and the fourline nudibranch
Fourline nudibranch
The fourline nudibranch, Polycera quadrilineata, is a species of dorid nudibranch. It is a marine gastropod mollusc in the family Polyceridae.-Distribution:...
. The animal may reach 30 mm in total length.