Milne-Edwards, 1848
The Opisthobranchia are a subclass of the gastropod molluscs. They are all hermaphrodite, marine and macroscopic. World-wide there are about 3000 species of opisthobranchs and 5% of these have been recorded from the shallow waters of the North Sea. Of these species, 30% are infaunal, the remainder epifaunal.
The opisthobranch subclass has been polyphyletic; numerous evolutionary lines of early prosobranchs have achieved success by abandoning total reliance upon a rigid external shell. In fact, the 'sea-slug' facies have arisen many times in more or less independent lines of evolution.
Source: Thompson, 1988.
The following subtaxa of this subclass occur in the region:
Order Acochlidioidea
Order Anaspidea
Order Cephalaspidea
Order Notaspidea
Order Nudibranchia
Order Sacoglossa
Suborder Aeolidiina
Suborder Arminina
Suborder Dendronotina
Suborder Doridina
Family Acteonidae
Family Aegiretidae
Family Aeolidiidae
Family Akeridae
Family Aldisidae
Family Aplysiidae
Family Archidorididae
Family Arminidae
Family Asperspinidae
Family Chromodorididae
Family Corambidae
Family Cylichnidae
Family Dendronotidae
Family Diaphanidae
Family Discodorididae
Family Dotidae
Family Elysiidae
Family Embletoniidae
Family Eubranchidae
Family Facelinidae
Family Favorinidae
Family Flabellinidae
Family Goniodorididae
Family Heroidae
Family Kentrodorididae
Family Lomanotidae
Family Microhedylidae
Family Onchidorididae
Family Philinidae
Family Philinoglossidae
Family Pleurobranchidae
Family Polybranchiidae
Family Polyceridae
Family Retusidae
Family Rostangidae
Family Runcinidae
Family Stiligeridae
Family Tergipedidae
Family Tritoniidae
Family Zephyrinidae
Subfamily Polybranchiinae
Genus Acanthodoris
Genus Acteon
Genus Adalaria
Genus Aegires
Genus Aeolidia
Genus Aeolidiella
Genus Akera
Genus Alderia
Genus Aldisa
Genus Ancula
Genus Aplysia
Genus Archidoris
Genus Armina
Genus Asperspina
Genus Berthella
Genus Cadlina
Genus Calliopaea
Genus Colpodaspis
Genus Corambe
Genus Coryphella
Genus Cuthona
Genus Cylichna
Genus Dendronotus
Genus Diaphana
Genus Doto
Genus Elysia
Genus Embletonia
Genus Eubranchus
Genus Facelina
Genus Favorinus
Genus Geitodoris
Genus Goniodoris
Genus Hermaea
Genus Hero
Genus Janolus
Genus Jorunna
Genus Limacia
Genus Limapontia
Genus Lomanotus
Genus Microhedyle
Genus Okenia
Genus Onchidoris
Genus Philine
Genus Philinoglossa
Genus Placida
Genus Pleurobranchus
Genus Polycera
Genus Retusa
Genus Rostanga
Genus Roxania
Genus Runcina
Genus Scaphander
Genus Tenellia
Genus Tergipes
Genus Thecacera
Genus Tritonia
Genus Volvulella
Acanthodoris pilosa
Acteon tornatilis
Adalaria proxima
Aegires punctilucens
Aeolidia papillosa
Aeolidiella glauca
Akera bullata
Alderia modesta
Aldisa zetlandica
Ancula gibbosa
Aplysia punctata
Archidoris pseudoargus
Armina loveni
Asperspina brambelli
Berthella plumula
Cadlina laevis
Calliopaea bellula
Colpodaspis pusillus
Corambe obscura
Coryphella browni
Coryphella gracilis
Coryphella lineata
Coryphella pedata
Coryphella pellucida
Coryphella verrucosa
Cuthona amoena
Cuthona caerulea
Cuthona concinna
Cuthona foliata
Cuthona gymnota
Cuthona nana
Cuthona pustulata
Cuthona rubescens
Cuthona viridis
Cylichna cylindracea
Dendronotus frondosus
Diaphana minuta
Doto coronata
Doto cuspidata
Doto dunnei
Doto fragilis
Doto millbayana
Doto pinnatifida
Doto tuberculata
Elysia viridis
Embletonia pulchra
Eubranchus cingulatus
Eubranchus doriae
Eubranchus exiguus
Eubranchus farrani
Eubranchus pallidus
Eubranchus tricolor
Eubranchus vittatus
Facelina bostoniensis
Facelina coronata
Favorinus blianus
Favorinus branchialis
Geitodoris planata
Goniodoris castanea
Goniodoris nodosa
Hermaea bifida
Hero formosa
Janolus cristatus
Janolus hyalinus
Jorunna tomentosa
Limacia clavigera
Limapontia capitata
Limapontia depressa
Limapontia senestra
Lomanotus genei
Lomanotus marmoratus
Microhedyle lactea
Okenia leachii
Okenia quadricornis
Onchidoris depressa
Onchidoris fusca
Onchidoris inconspicua
Onchidoris luteocincta
Onchidoris muricata
Onchidoris pusilla
Onchidoris sparsa
Philine angulata
Philine aperta
Philine catena
Philine pruinosa
Philine punctata
Philine quadrata
Philine scabra
Philinoglossa helgolandica
Placida dendritica
Pleurobranchus membranaceus
Polycera dubia
Polycera faeroensis
Polycera notha
Polycera quadrilineata
Retusa obtusa
Retusa truncatula
Retusa umbilicata
Rostanga rubra
Roxania utricula
Runcina coronata
Scaphander lignarius
Tenellia adspersa
Tergipes tergipes
Thecacera pennigera
Tritonia hombergi
Tritonia lineata
Tritonia plebeia
Volvulella acuminata