Glaucilla marginata
Bergh, 1860

Family: Glaucidae


Circumglobal in temperate and tropical waters.


Collaroy Beach, Sydney, New South Wales. February 1987. 35mm long alive. Photographed from above to show foot - both Glaucilla and Glaucus float upside down.
PHOTO: Bill Rudman.


Glaucus atlanticus

Both Glaucus and Glaucilla appear to be "monotypic" genera. That is each genus has only one species. The main external difference is that in Glaucus the cerata are arranged in a single row in each arch while in Glaucilla there are multiple rows. The biology of the two species is discussed under Glaucus atlanticus.

See photos of pelagic egg strings.

• Bergh, L.S.R. (1860). Om Forekomsten af Neldefiim hos Mollusker. Vidensk. Meddel. Naturh. Foren. Kj√∂benhavn, p. 309-331, pl. 8

Authorship details
Rudman, W.B., 1998 (November 6) Glaucilla marginata Bergh, 1860. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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