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.
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. Kjöbenhavn, p. 309-331, pl. 8
Rudman, W.B., 1998 (November 6) Glaucilla marginata Bergh, 1860. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/glaumarg
February 13, 2009
From: Gary Cobb
Concerning message #22156:
Hi Bill and everyone!
This time the topic is Glaucilla marginata. There are not very many entries for this little beauty, so here we go.
This species is quite common along the beaches after a big onshore wind. They are typically quite small compared to Glaucus atlanticus. I have included a great frontal shot clearly showing the multi-layered cerata [upper photo]; a photo comparing size of large G. atlanticus and small G. marginata [middle photo]; and a mating pair [lower photo]. During the mating I was quite amazed at the actual size on the sexual organ. Nearly the length of the 'arm'. My guess is that with a short organ would not reach because of the size of the 'arm'.
Locality: Mooloolaba, Sunshine Coast, stranded on beach, Queensland, Australia, Pacific Ocean, 20 January 2009, Pelagic. Length: 5-17 mm. Photographer: Gary Cobb.
firstname.lastname@example.orgCobb, G.C., 2009 (Feb 13) Glaucilla marginata from sthn Queensland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22167
Thanks for this great set of photos. Glaucilla marginata is often overlooked when found with the much larger Glaucus atlanticus. Both species have extremely large copulatory organs and your suggestion that it is because they can't get close together is eminently reasonable. I think Charles Darwin - whose 200th birthday we are celebrating at present - was the first to note the extremely long penis of the humble barnacle - proportionally the longest in the animal kingdom - an adaptation for an animal permanently stuck on a rock. A long penis is their way of getting 'close together'.
January 20, 2009
From: Rob Blackmore
Concerning message #21205:
Hi there, I have just discovered many similar creatures at Mount Coolum beach on the Sunshine Coast today. I think they are probably more likely to be Glaucilla marginata? a close relative of Glaucus atlanticus.
Locality: Mount Coolum beach, Beach, Queensland, Pacific Ocean, 15 Jan 2009, Inter-Tidal beach. Length: 7 mm. Photographer: Rob Blackmore.
email@example.comBlackmore, R.H., 2009 (Jan 20) Re: Tiny, elaborate creature at Stradbroke Island, Queenslan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22156
Yes this is Glaucilla. On reflection, Ken Thomas's animal - which your refer to - could well be Glaucilla marginata rather than Glaucus, but its a bit hard to be sure from the photo.
January 21, 2001
From: Julia Busch
Thank you for answering my question quite fast!! I am preparing an oral presentation and had a lack of information. Yes, I am, too, interested in the research, maybe it is possible in the next years or after my marine biology study.
firstname.lastname@example.orgBusch, J., 2001 (Jan 21) Re: Nematocysts in Glaucilla. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3577
January 20, 2001
From: Julia Busch
Is there any actual research about Glaucilla's utilization of nematocysts?
email@example.comBusch, J., 2001 (Jan 20) Nematocysts in Glaucilla. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3568
Although Glaucus atlanticus and Glaucilla marginata are in separate genera, this is probably an unnecessary inflation of their taxonomic rank. In anatomy and natural history they are very close and probbaly should be in a single genus. To my knowledge there are only the two papers by Thompson & Bennett which study the nematocysts found in the cnidosacs of these two species, and they identified them as belonging to Physalia and Porpita. They also showed that the nudibranchs accumulate the largest, most penetrating, nematocysts from their prey. The references are on the Glaucus atlanticus Page.
Is your interest general, or are you undertaking some research on these fascinating animals?
January 29, 2000
From: Orso Angulo
I wonder if you or any of the brancher that visit your site could help me. I'm searching for information regarding reported localities of G. marginata on the Pacific coast of North America (if there are any).
Allende #1245 E/Felix Ortega e Isabel la Catolica
La Paz, B.C.S.
firstname.lastname@example.orgAngulo, O., 2000 (Jan 29) Glaucilla marginata - any east Pacific records?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1814