Are there freshwater sea slugs?

June 17, 2006
From: Dave

My apologies if this was placed in the wrong area but I have only recently heard of a (or possibly several?) freshwater species of slug and after a lot of googling come across only vague refrences but no real details or species name(s). Would it be possible to finds out more information or if you'd rather, point me in a general direction?

Dave, 2006 (Jun 17) Are there freshwater sea slugs?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Dave,
There is one Order of opisthobranchs - the Acochlidea - which have freshwater species. Most acochlidian species are small worm-like marine slugs found living between sandgrains - part of what we call the interstitial fauna. However some have invaded brackish water and others freshwater. One small species, Tantulum elegans, is found in a mountain swamp on the Caribbean island of St Vincent. However most of the others we know of are much larger than usual, up to 3 cm in length, and live in rivers and streams on several tropical Pacific islands.

I can't guarantee a complete list of freshwater species, but here are some I know of:
Strubellia paradoxa (Strubell, 1892) - Solomon Islands
Acochlidium amboiense Strubell, 1892 - Amboina, Indonesia
Acochlidium weberi bergh, 1896 - Flores, Indonesia
Acochlidium suteri Wawra, 1979 - Sumba, Indonesia
Acochlidium bayerfehlmanni Wawra, 1980 - Palau
Acochlidium fijiiensis Haynes & Kenchington - Fiji.
Tantulum elegans Rankin, 1979 - St Vincent Is., Caribbean

If anyone has photos of any of these species I would like to include them on the Forum.

See the message from Michael Schrödl & Timea P. Neusser [#15744] which summarises our knowledge of the group. A recent publication is:

  • Haynes, A. & Kenchington, W.  (1991) Acochlidium fijiiensis sp. nov. (Gastropoda: Opisthobranchia: Acochlidiacea) from Fiji. The Veliger, 34(2): 166-171.
  • Rankin, J. R. (1979) A freshwater shell-less mollusc from the Caribbean: structure, biotics, and contribution to a new understanding of the Acochlidioidea. R O M Life Sciences Contributions 116: 1-123.

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Jun 17). Comment on Are there freshwater sea slugs? by Dave. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from



Related messages

  1. Information on Tantulum elegans
    From: Sarsha Lall, August 31, 2006
  2. Phylogeny and evolution of acochlidian opisthobranchs
    From: M. Schrödl & T. P. Neusser, February 6, 2006

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