Key to Order Nudibranchia

[Nudibranchs have exposed, unprotected gills.  Adults have no shell (the larval shell is lost).]

Taken primarily from  Kozloff, 1987, 1996  (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)

Jump to:
Lower taxonomic level	Main Page	Alphabetic Index	Systematic Index	Glossary

 

1a	Anus, partly or completely encircled by gills, located on the midline of the dorsum, one-half to three-fourths of the body length from the anterior end	Suborder- Doridacea (In part)
1b	Anus not located on the midline of the dorsum ( it is either on the right side, on the dorsum near the right side, or at the posterior end of the body; if gills are present, they are not arranged in a partial or complete circle around the anus)	2
2a	Anus at the posterior end of the body, on the midline, in a deep groove in the mantle between the foot and the edge of the dorsum; dorsum without any outgrowths other than the rhinophores	Suborder- Doridacea (In part)
2b	Anus on the right side of the body, or on the dorsum near the right side; dorsum usually with outgrowths (simple or branched cerata, or gills) in addition to rhinophores ( if dorsal outgrowths are not present, the dorsum has several white longitudinal ridges on a pinkish brown background)	3
3a	Without dorsal outgrowths other than the rhinophores; dorsum with several white longitudinal ridges on a pinkish brown background	Suborder- Arminacea: Armina californica
3b	With dorsal outgrowths (cerata or gills) in addition to the rhinophores; dorsum without white longitudinal ridges	4
4a	Clavus of the rhinophores partly or fully retractile into the sheath; dorsal outgrowths either club-shaped cerata (with rings of prominent tubercles), paddlelike or bushy cerata, or bushy gills (as a rule, there are 4 to 10 cerata or numerous gills arranged in each of 2 dorsolateral longitudinal series)	Suborder- Dendronotacea
4b	Clavus of rhinophores not retractile into a sheath (each rhinophore stands free; it has no sheath); dorsal cerata cylindrical, lanceolate, or leaflike, usually numerous (more than 20) and usually arranged in transverse rows	5
5a	Anus on a conspicuous papilla near the right side of the posterior third of the dorsum, usually among the posterior third of the cerata	Suborder- Arminacea (in part)
5b	Anus on an inconspicuous papilla near the right side of the anterior half of the dorsum, usually among the anterior third of the cerata	Suborder- Aeolidacea

  Suborder Aeolidacea
  Armina californica
  Suborder Arminacea
  Suborder Dendronotacea
  Suborder Doridacea