Opisthobranchia

The opisthobranches ( Opisthobranchia ) are a subclass Gastéropode S.

Opisthobranche (of the Greek opisthen , behind, behind) means " Gill on the back of the corps" , contrary to Prosobranche (of the Greek proso ahead) which wants to say " gill on before corps".

Their visceral mass has only one torsion of 90° (and not 180°) compared to the head-foot unit, which distinguishes them from the gastropods Prosobranche S.

They are exclusively sailors and their shell is reduced or absent. They are divided into two groups:

the Tectibranche S which have a vestige of shell (intern) and gills internal (Aplysie or Lièvre of sea)
the Nudibranche S whose gills are external

List orders

Selong ITIS :

subclass Opisthobranchia

order Acochlidioidea
order Anaspidea
order Cephalaspidea P. Fischer, 1883
order Gymnosomata Blainville, 1824
order Notaspidea
order Nudibranchia Blainville, 1814
order Sacoglossa
order Soleolifera

External bonds

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