Janolus fuscus

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Janolus fuscus
Janolus fuscus 3.jpg
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
(unranked): clade Heterobranchia

clade Euthyneura
clade Nudipleura
clade Nudibranchia
clade Dexiarchia
clade Cladobranchia

Family: Proctonotidae
Genus: Janolus
Species: J. fuscus
Binomial name
Janolus fuscus

Janolus fuscus is a species of sea slug, or more accurately a nudibranch, a marine gastropod mollusk in the family Proctonotidae.


The species Janolus fuscus is found from the Kenai Peninsula, Alaska to central California and also in northern Japan.[1]


This species of nudibranch is found in shallow and subtidal waters.


Janolus fuscus, head end towards the top

The bodies of nudibranchs in this species are semi-translucent. The body is covered in short cerata. In Janolus fuscus the cerata are orange and white tipped.

Life habits[edit]

Janolus species feed on Bryozoa.

Janolus fuscus


In California, Navanax is a known predator of Janolus. Navanax tracks the slime of Janolus by using chemoreceptors. When Janolus is about to be caught, it rolls into a ball, leaving its cerata exposed. If there is a water current, as if often the case, the sea slug may then be passively rolled away from the predator.


  1. ^ "Janolus fuscus". Sea Slug Forum. Archived from the original on 13 July 2007. Retrieved 24 December 2006. 

External links[edit]

  • Sea Slug Forum info at: [1]
  • SlugSite info: [2]