Marionia viridescens from Red Sea

May 19, 2005
From: Oren Lederman

Hi Bill,

These photos were taken during a night dive. While taking these photos another diver pointed his (strong) torch at the Marioniopsis. It squirted some kind of liquid and slowly started to back off and hide between the corals. Can you explain this behavior ?

Locality: The "Dekel" beach (night dive). Israel, Red Sea. Depth: ~25 meters
Length: ~5 cm. 12 May 2005. corals. Photographer: Oren Lederman

Oren Lederman

Lederman, O., 2005 (May 19) Marionia viridescens from Red Sea. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Oren,
I'm still trying to work out these large tritoniids. My best guess is that this is a colour form of Marionia viridescens (Eliot, 1904). Infortunately there are quite a few Indo-West Pacific species which have been described from a few preserved animals so it is difficult to know what is a good species and what is just a colour form. I am intersted to hear of the colour squirting episode. I have not experienced this myself but it is possible they have some defensive secretions they use this way. Tritoniids feed on soft-corals, which are loaded with nasty anti-feedant chemicals, so it is quite possible they are retaining soft-coral metabolites and re-using them.
Best wishes,
Bill Rudman

Rudman, W.B., 2005 (May 19). Comment on Marionia viridescens from Red Sea by Oren Lederman. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from