Dear Leena,

It's a bit hard using terms like 'rare' and 'uncommon'. If we don't know where an animal lives then we should say 'rarely found' as the species may be extremely common in their normal habitat.  As you'll see if you read the messages on various species of Chelidonura on the Forum, a species can be found in great abundance for a short period and then be absent so it goes from being abundant to rare in a few weeks. So if I say Chelidonura pallida appears to be uncommon what I am really saying is we don't have many records of it which might mean its rare or it might mean we don't know where it lives. 

Best wishes,
Bill Rudman

Dear Leena,
Thanks for the record. This species does seem to be as common as some other species of Chelidonura so new records are very welcome. I am not sure if you realised, but your animal is in fact two animals mating. In the photo alongside I have labelled the head of the posterior animal and the right parapodia of each animal. Aglajids, like Chelidonura pallida, are similar to sea hares in their mating behaviour [see mating chains ], because their penis is on the right side of the head, quite separate from the female part of their genital organs which are on the right side of the body about halfway back in the mantle cavity. [I have ringed the region in your photo]. If you look at the photos and messages on Chelidonura varians you will find quite a few reports on mating and egg laying.

Best wishes,
Bill Rudman

Dear Danny,
Yes this is an interesting find. We don't know a lot about this species, so any new information is welcome.

Your close-up of the head shows the chemo-sensory 'sensory bristles' on mounds on each side of the mouth. We thinks there are used to sense prey or the mucous trails of the flatworms species of Chelidonurafeed on.

Best wishes,
Bill Rudman

Dear Roberto,
Thanks for the records. One value of the Forum is to give us a chance of building up a better idea of just how common, various species are. Enormous private and public shell collections have enabled us over time to build a quite good understanding of the geographic distribution of many shelled molluscs and to gain an understanding of just how common individual species are. Unshelled molluscs, such as the sea slugs, are quite a different story. Collections of any value are much more difficult to accumulate, because preserved specimens of one species look much like those of another. To be of value, specimens need to be properly fixed and preserved when collected, and accompanied by information on their living shape and colour such as drawings, field notes, paintings and more recently colour photographs.  In many ways, colour photographs are as valuable in sea slug research as shells are in 'snail research'.
Best wishes,
Bill Rudman

Dear Sascha,
Yes this is Chelidonura pallida. It is interesting that this is the second message in a few days showing an unusual colour form - in this case black spots [see message #13655].
Best wishes,
Bill Rudman

Dear Alphonsus,
This is indeed Chelidonura pallida. This seems to be quite a rare species, or at least rarely seen species so its good to get some more information on variability in is colour pattern. In your photo alongside I guess the animal on the neck of the bottle is also Chelidonura. I can't make out its shape very cleaely and I have never seen a specimen in which the yellow lines are reduced to a series of yellow spots in the black band.
Best wishes,
Bill Rudman

Thanks Linda,
This is a nice find. This species seems to be one of the less common species of Chelidonura so it is useful to get a range of records showing its colour varaition and geographic distribution. Your trip to Indonesia seems to have been quite productive
Best wishes,
Bill Rudman

Thanks Atsushi,
Your messages on variability in Chelidonura are very valuable. I'm sorry we can't answer all your questions, but your messages are certainly helping us to better understand these animals.
Best wishes
Bill Rudman