Spanish Dancers - information please

[World Wide Diver]

Attached is a photo of two spanish dancers in what we think is a mating position. The spanish dancers are in a fairly unusual colour phase - blue (we have seen red, yellow and orange).

Note that the spanish dancers were both releasing a mustard coloured cloud of liquid from the area of their gills (lungs) and were in a '69' position.

Described mating of spanish dancers does not specify what the liquid is. (sperm or something else?!)

Has anyone seen this before/can explain this behaviour?

Cheers.

 

[joebubbles]

Hi WWD,
I have a picture of the results of mating--Spanish Dancer eggs! What is unique about the attached picture is that the ribbon of eggs are in the shape of an almost perfect floral pattern. The picture was taken on May 1st, 2009 and not too far away from GenSan at Bangka Island! Bangka Island is near that other Tuna Capital--Bitung, North Sulawesi.

Pink Ribbon Eggs - Spanish Dancer! on Flickr - Photo Sharing!

 

[Kupu]

I would guess the cloud is a chemical defense, the exact properties of the chemical varies depending on the species. A number of nudibranch species are able to release strands or clouds in this manner when threatened. I doubt this would normally happen during reproduction, but perhaps the presence of divers near by was percieved as a threat. I am not aware of any nudibranchs that release clouds of eggs and sperm as part of reproduction.

The food source of the nudibranch would probably affect the color of the release. The couple of times I have seen this behavior, the release was milky white. Certain species have numerous small glands on the mantle used to store the chemical and others have larger specialized sacs for this use. Since the release is localized to one area in this case, it would seem these nudibranchs have the larger sacs located behind the gills. I have observed phyllid nudibranchs release the chemical as strands from numerous parts of the mantle, the strands would slowly disperse into a cloud.

Any corrections are welcomed, this is just my understanding based on time spent online and checking the books I have on hand. Doing a search for defense on The Sea Slug Forum yields interesting info on this topic.

 

[Babydamulag]

Contact these folks -------> The Sea Slug Forum - Home Page
They are the ultimate authority on sea slugs.

 

[World Wide Diver]

I would guess the cloud is a chemical defense, the exact properties of the chemical varies depending on the species. A number of nudibranch species are able to release strands or clouds in this manner when threatened. I doubt this would normally happen during reproduction, but perhaps the presence of divers near by was percieved as a threat. I am not aware of any nudibranchs that release clouds of eggs and sperm as part of reproduction.

Thanks Dustin. The spanish dancers were releasing the yellow fluids when they were spotted (by Yoyong Salucot - credit to him).

It just seems like their allignment suggested a mating positions and we assumed that they took the '69' position like this to mate - male/female and female/male.

We have seen holuthurians release a simular coloured fluid when reproducing (but on their own!). I photograhed this and can post photos if this is relevant.

Just that we have never seen this before/seen this documented on the net.

Do you have any links that you can post?

Thanks a lot.

 

[Kupu]

The nudibranchs are in the correct position for mating for most sea slugs. All species but one are hermaphrodites, so there is no real male/female distinction, just an exchange of DNA during mating. This photo of Hypselodoris sp shows the action. Afterwards they both lay egg ribbons, as shown by joebubbles.

Agree that there is not much info available about the yellow release shown in your photo. It is very interesting, and I think it would be great if you cropped the photo down just a little to show just the nudibranchs, and then submit it to the Sea Slug Forum. I expect they would love to have that photo in order to document the behavior, and that would add the the online knowledge base for future use. Also the very unusual color and bumpy mantle had me thinking it might not be Hexabranchus sanguineus, but it is be the only match I can find. Another feature that would be great to add to the Sea Slug forum database.

Here are a couple links to document the ability of sea slugs to release chemicals. Sea hare ink, defensive glands in Hypselodoris, mucus from Glossodoris cincta. There are a few more, but you get the idea. Although these references are not a great match to what is happening in your photo, at least they might provide clues as to what is happening.

Again, I hope you would be willing to submit these photos to a slug forum for a more educated opinion. Quite curious for a better explanation since I very interested in anything having to do with sea slugs.

 

[World Wide Diver]

Dustin - we have attached a photo showing the place where the fluid was being discharged from. It was a orifice that seemed to contract then open - looked a bit like a volcano when spewing out yellow clouds of the stuff. The discharge seemed to coagulate then cling/hang over rocks and the nudibranch.

We looked at the sequence of photos - they were definitely joined and mating as per the photo you attached. Also, the larger spanish dancer exposed more of its gills as we approached and then did seem to emit the fluid. This does seem to fit with defensive behaviour.

Anyhow, we did not hassle them/stay with them for very long, as they did seem quite busy

We will submit some hi-res photos to the sea slug forum as you suggested.

 

[World Wide Diver]

I have a picture of the results of mating--Spanish Dancer eggs! What is unique about the attached picture is that the ribbon of eggs are in the shape of an almost perfect floral pattern. The picture was taken on May 1st, 2009 and not too far away from GenSan at Bangka Island! Bangka Island is near that other Tuna Capital--Bitung, North Sulawesi.

Thanks for the link to your photo. Bangka Island is 570km away from where our photo was taken (Punk Rock, Samal Island) - almost a straight line along the Sangihe Archipelago dot-to-dot..

 

[Kupu]

Haha. OK, I should have thought of this before.

After seeing your latest closeup picture, it seems that what you saw is simply nudi poop. It is clearly coming from the anus. That makes much more sense also, considering that you said the nudi exposed more of its gills, normally it would retract the gills if it was acting in a defensive manner. Interesting that both nudis are doing this at the same time, perhaps a result of relaxing during the mating process. It seems you were there at the right time to document the behaviour, but perhaps they were to preoccupied to pay much attention to you.

Thanks for adding that picture, very helpful.

 

[World Wide Diver]

LOL - yes, something you don't see every day! I still try and post on the sea slug forum, but it seems that they are not accepting new posts at the moment (until January!!).

Thanks again for solving the mystery.