Blue Sea Slug

Photo by ShannaB

Published on Project Noah

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Field Notes

Notes:

We found these two tiny nudibranchs on our local beach this afternoon, washed up with a heap of bluebottles (Portuguese Man'O'War). Each is under a centimetre long, probably closer to 7-8mm. We scooped them up in a shell for these pics. These little creatures float upside down on the surface tension of the water. They are the only species in the genus Glaucilla, but are closely related to the larger (and showier) Glaucus atlanticus (http://en.wikipedia.org/wiki/Glaucus_atlanticus).

Update 5/10/14 - This species appears to have been reclassified. I have updated the scientific name to Glaucus marginata accordingly.

Reference Links:

Glaucilla marginata, The Sea Slug Forum - Glaucilla marginata

Species ID Suggestions

Comments (47)

HazelMarley

I never knew those existed

hamzee413

Absolutely beautiful! They're like tiny dragons~

ShannaB

Thanks Neil. I got stung by a bluebottle once but it didn't affect me too badly - I think I was just lucky! Mostly, as a born and bred inlander, I just avoid bluebottle stings by staying well out of the water... ; ) I feel really lucky to have found these slugs when we did, I haven't seen them since... I'm desperate to find a Glaucus atlanticus too, but no luck. Actually that's what I was hoping to find the afternoon a couple of weeks ago when I came across that baby turtle!!!

Neil Ross

Great series, Shanna. I'd forgotten all about these little beasties. So beautiful. Haven't seen one since I was a kid. These would wash up, and blue bottles weren't far behind. I always seemed to find the blue bottles whilst in the surf. Developed good immunity, I think. I was certainly stung enough.

RayTung

Blue dragon! amazing shot!

ShannaB

They certainly are, Tic! : )

TicThapanya

very beautiful organisms

Brian Muñiz

I actually do, they look so similar to one another that their differentiation may have happened recently by evolutionary standards. They have the same blue coloration on the top to hide from predators from above and the silver below to hide from deepwater predators, and the fact that you mention the man o war is a great indicator that they are very similar, at least were I live there are some seasons where you cannot go to the water because man o war's arrive, as well as other deadly jellyfish and many that just hurt alot.

ShannaB

Thanks Scott. : )

ShannaB

Thank Gilma! Brian, thanks for the link. The info all seems to be about Glaucus atlanticus... there's hardly anything on Glaucilla marginata. Do you think the same info applies to both species? (Glaucilla marginata really seems to be the poor cousin!!)

Brian Muñiz

Here's a link about their diet: http://en.m.wikipedia.org/wiki/Pelagic_sea_slug

Gilma Jeannette Ospino Ferreira-Norman

WOW!! Lovely!! Never seen them before. Great pictures.

ShannaB

It sure is, Dixie! : )

Dixie

Amazing!

ShannaB

Thanks Jason, Braulio and Adarsha!

Adarsha B S

Wow ! what an amazing creation!

Braulio Rivas Tapia

Just amazing!

Jason Alexander

Wonderful!

ShannaB

Haha Sheikanah, I see what you mean! But definitely not a fighting fish. : )

shekainah d. alaban

amazing creature, thought t'was a fighting fish.

ShannaB

Thanks Yuriana, Yuko, Ali, Holly, Yasser, Brian and Seema. Brian, I did read somewhere that they eat physalia and take their stinging cells but I couldn't find a reliable source!! (And we didn't know this when we found them... and we picked them up. Fortunately we didn't get stung!)

Seema

very unusual shape,,,,

Brian Muñiz

Beautiful little guys, the pelagic sea slug actually feeds on the physalia or portuguese man o' war which is why you found them with it. They also take the stinging cells from the host for protection so I wouldn't touch them haha. Never seen one in person but they are interesting little nudibranches.

Gorgeous.

Cool

VERY NICE...:)

How could I totally miss this amazing spot?!?! :O Absolutely beautiful and unbelievable!

YurianaMartínez

beautifull!

LeanneGardner

That small! Oh my goodness, I'll have to take my glasses! Ha :)

ShannaB

They are TINY Leanne, and when they're washed up they kind of bunch into a ball no more than 5mm across. Look for a little blob of blue! : )

LeanneGardner

I just have to keep coming back to this lovely little creature. This is such a fantastic spotting Shanna. My eyes will be peeled now on future trips to the beach!

ShannaB

Thanks Karen, Jakubko, Rieko, Marta, Argy, Toshimi and Noel. @Marta - I did try to put them back in but because they were washing up in the surf they just seemed to get washed up again. : ( @Argy - I found a Flickr photo where the photographer has cited an Australian Museum source saying that these guys "feed on the 'bluebottle' or 'Portugese man o' war', Physalia. They store the most powerful of the bluebottle's stinging cells at the tips of their slender cerata (20mm)." Unfortunately the link to the source is dead and I can't find this info anywhere else!

KarenL

Wow! Awesome spot Shanna!

Jacob Gorneau

Beautiful!

RiekoS

Beautiful slugs and beautiful pictures. Thank you very much for sharing.

The MnMs

Wonderful spotting! I´d love to find them some day. Did you release them back in the sea afterwards?

Mark Ridgway

Fantastic find. I suppose they do the same trick of incorporating the Man-o-War cnidoblasts for their own purposes.

ToshimiDowaki

Beautiful creature and shots!