Originally recorded from Japan, and since from northwestern Australia. Records in the Forum from the Indian Ocean [Maldives] and various islands in tropical western Pacific.
UPPER: Ashmore Reef, Kimberley region, northwestern Australia. LOWER: Cartier Island, Kimberley region, northwestern Australia. PHOTOS: Clay Bryce.
These photos provided by Clay Bryce, Western Australian Museum to show the range of colour variation in Western Australia. See message below asking whether this shows that T. vittata is a synonym.
• Baba, K. (1972). Thecacera picta spec. nov. from Suruga Bay, Japan (Nudibranchia: Doridoidea: Polyceridae). The Veliger, 15(2): 88-90
Rudman, W.B., 1998 (November 13) Thecacera picta Baba, 1972. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/thecpict
January 22, 2009
From: Marcel Tanke
Concerning message #22026:
Within a few meters from each other, we found several gray and black Thecacera picta on the sandy bottom of Anilao Secret Bay dive site. I think this supports the link with the white T. picta, as per the previous message.
Locality: Anilao, 10 meters, Philippines, 1 January 2009, sandy, flat bottom . Length: 2 cm. Photographer: Marcel Tanke.
email@example.comTanke, M.A., 2009 (Jan 22) Black Thecacera picta from Philippines - 2. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22160
I think that we can be pretty certain that these are all one species
November 25, 2008
From: Marcel Tanke
Concerning message #22026:
Here are two more Thecacera picta. I think they have again another colour pattern variation. We found them in a rather strong current. They were holding on to and maybe eating from, a small hydroid. It seems like the top one has white gills with a couple of relatively large black dots. The lower one has small red dotted gills, which you can see just in the middle between them.
15 m, Maldives, 26 December 2007, Sandy bottom. Length: 1 cm. Photographer: Marcel Tanke.
Marceltanke@cs.comTanke, M.A., 2008 (Nov 25) Variation of Thecacera picta from Maldives. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22049
Thanks for the interesting photo. The dotted 'gills' in the lower animal are in fact a branched bryozoan colony that this species eats [see messages #5771, #20058, #21602]. This colony seems to have quite a long stalk which the upper animal has crawled up and consequently bent over.
It interesting how many photos there are of tropical species of Thecacera crawling over what seems to be a wasteland of sand, apparently lacking any food. Photos like yours show that food, such as bryozoan colonies can be found wherever there is a small rock, or large shell fragment, for them to attach to.
November 13, 2008
From: Marcel Tanke
Concerning message #12845:
We found this black Thecacera in Puerto Galera, which looks like Thecacera sp. 3. About 1 meter from it were two 2 gray/white animals.
The black one here has several small additional appendages, abnormalities?
Locality: Puerto Galera, 15 m, Philippines, 10 February 2008, sandy bottom. Length: 1 cm. Photographer: Marcel Tanke
Marceltanke@cs.comTanke, M.A., 2008 (Nov 13) Black Thecacera from Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22026
Thanks for these photos. They solve the mystery of Thecacera sp. 3, as I am sure your greyish animals link the blackish one to the white Thecacera picta. Certainly the greyish ones are T. picta.
Concerning 'abnormal' appendages: the small orange-tipped papillae at the base of the large appendages by the gills are unusual, but the ones up near the rhinophores are sometimes found in T. picta. I am not sure about the large flap on the inside of the right rhinophore. It is possibly the sheath that usually surrounds the rhinophore club in this species. If it is, it is possibly misplaced through some damage or abnormality.
August 11, 2008
From: Marcel Tanke
Locality: Anilao, dive site Twin Rocks, 15 m, Philippines, 12 July 2008, Sandy bottom. Length: 1 cm. Photographer: Marcel Tanke.
firstname.lastname@example.orgTanke, M.A., 2008 (Aug 11) Thecacera picta from Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21745
Yes the papilla on the outer edge of the right rhinophoral sheath is certainly split in two. Looking at other photos of this species and other species of the genus, this does indeed seem to be uncommon.
June 6, 2008
From: Teresa Zuberbühler
Concerning message #20058:
Here another picture of Thecacera picta eating bryozoans. There were two of them, nearly fighting for their favorite food.
Locality: Lembeh, 15m, Sulawesi, Indonesia, Pacific, July 2004, sand and rubble with little coral cover. Length: 2.5cm. Photographer: Teresa (Zubi) Zuberbühler.
Zuberbühler, T., 2008 (Jun 6) Re: Feeding Thecacera picta from Vanuatu. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21602
It is always good to get another record of a nudibranch feeding
September 6, 2007
From: Valda Fraser
Always great to find a nudibranch that I have never seen before. Think it is Thecacera picta. Links very closely in colouration to the image submitted from Australia on the Factsheet.
Locality: Pomene, 20 m, Mozambique, Indian, Reef. Length: 10 mm. Photographer: Valda Fraser.
email@example.comFraser, V.J., 2007 (Sep 6) Thecacera picta from Mozambique. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20632
It's good to know you are still keeping an eye open for nudibranchs. Yes this is a heavily spotted form of T. picta.
July 25, 2007
From: Kerem Turker
Concerning message #20058:
Here is another feeding information for Thecacera picta, Raja Ampat Indonesia. Within the same sponge there were 5-6 individuals feeding. They seemed to be enjoying the food. The strong current affected the quality of the pics as these guys are hard to find and focus as being "translucent clear".
Locality: Kri Island, Raja Ampat, 12 meters, Indonesia, Western Pacific , 20 March 2007, Reef wall . Length: About 1 cm. Photographer: Kerem Turker.
firstname.lastname@example.orgTurker, K., 2007 (Jul 25) Re: Feeding Thecacera picta from Vanuatu. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20177
It is not clear what your animals are eating. It won't be the sponge. In the middle photo I can see some 'plant-like' growths which may be bryozoan colonies, but its not clear enough to be certain
July 9, 2007
From: Barbara Hanchard
Concerning message #19706:
The attached photo lends support to the idea [message #5771] that Thecacera picta feeds on aborescent bryozoans. This chap was happily munching away. Third occasion of sighting this species in the Solomon Islands for me.
Locality: Beside the "Wreck of the Ann" Russell Islands, 15 metres, Solomon Islands, Pacific Ocean, 16 June 2007, Sandy slope. Length: 25 - 30 mm. Photographer: N. Barbara Hanchard.
I have photos of the other two separate occassions of sighting in 2005 on Guadacanal but they are not feeding and photo quality predates current camera capabilities and skill.
Hope this of use to your database?
email@example.comHanchard, N.B., 2007 (Jul 9) Feeding Thecacera picta from Vanuatu. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20058
The first thing I noticed when I opened your message was the animal apparently feeding on the bryozoan. With Erwin's observation [#5791] and yours, I think we can say its food is known. If we had prizes to offer, you would definitely win this weeks prize.
April 3, 2007
From: Josh Jensen
Concerning message #19706:
It was quite awhile ago and I may have over estimated the size but I recall it being quite large, at least 50 mm for sure.
firstname.lastname@example.orgJensen, J.P., 2007 (Apr 3) Re: Thecacera picta from Vanuatu. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19792
Thanks for getting back to me. When I see a measurement which is far outside the norm, it's worth checking. I realise 'accurate' measurements from memory are not possible, so its worth knowing its an estimate.
March 30, 2007
From: Josh Jensen
This slug was moving quickly over a sand and rubble bottom with scattered sea grass and coral bommies at night. It didn't stop to feed on anything while I was watching. The dive site was the President Coolidge wreck and the slug was near the safety stop area on the way up the steep slope so the depth info may be irrelevant as only 100 m either side could have the slug on the beach or at 60 m depth.
Locality: Near wreck, shore dive, 8m, Vanuatu, Western Pacific, 20 December 2004, Sand slope between beach and 60 m. Length: 70 mm. Photographer: Josh Jensen.
email@example.comJensen, J. P., 2007 (Mar 30) Thecacera picta from Vanuatu. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19706
This is Thecacera picta. Could you confirm the length please? 70 mm is quite a bit larger than most specimens that have been reported. That is not to say you haven't found a very large specimen, but since 25 - 30 mm is the usual size, I think it is worth checking.
January 24, 2006
From: Rokus Groeneveld
Today I was checking out some information about Thecacera picta. I noticed they are all more or less white. And because you write in one of your comments not very much is known about the colour variations I send you this picture.
The slug in this case is kind of red. It's not the reflection from the sponge it's on. But is it because it eats it, or an adaptation as camouflage?
Locality: Cabilao Island, Philippines, Visayan Sea. Depth: about 20 meters. Length: about 1 cm. 25 December 2005. wall. Photographer: Rokus Groeneveld
firstname.lastname@example.orgRokus G., 2006 (Jan 24) Reddish Thecacera picta. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15590
I am pretty sure the red colour is caused by the sponge it is sitting on. These animals are very watery with not much in the way of a thick muscular body wall, so when they don't have any pigment in their skin, we can see through them, very much like we can see shapes and colours through frosted glass. We can see a yellow-brown lump in the middle of the body, which is the digestive gland, and somw whitish bits in front, whcih are parts of the reproductive system and gut. The fact that we can see things inside the body like this shows just how transparent this species is. Since we can't see through it very clearly we say that it is 'translucent clear' rather than transparent. I guess being almost transparent like this is a good simple way to camouflage yourself. Of course not all nudibranchs are translucent or transparent, many such as the chromodorids are hightl coloured.
December 31, 2004
From: Ian Dunsmore
Note added 13 November 2008: This is a dark form of Thecacera picta. See message #22026.
These photos were taken in May 2004 in Seraya Bay, north Bali. I am assuming this is a relative of Thecacera sp. 2 on the Forum but have not come across many photos of this critter.
Locality: Seraya Bay, north Bali, Indonesia
Depth: 12-15m. Length: 20mm. 20 May 2004
Black sandy volcanic slope, shore dive.
Photographer: Ian Dunsmore
Hope these are of interest.
Dunsmore, I., 2004 (Dec 31) Thecacera from Bali. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12845
Thanks for this. If it weren't for the gills you can see in two of your photos I would have had my doubts about it being a nudibranch. I agree that it looks as though it is a Thecacera, but it is not a species I am familiar with.
November 19, 2003
From: Ginette Allard
This is from Lembeh Strait, Indonesia.
Is it Thecacera picta ?
email@example.comAllard, G., 2003 (Nov 19) Thecacera picta from Indonesia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11353
It certainly looks like Thecacera picta.
May 20, 2003
From: Asther M. Lau
Please help identify this species that I've found recently. is it Nembrotha???
Date: 27th April 2003
Location: Tanjung Api, Tenggol Is. Malaysia
Asther M. Lau
firstname.lastname@example.orgLau, A.M., 2003 (May 20) Damaged Thecacera picta from Malaysia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9817
This is damaged specimen of Thecacera picta. Something has bitten off its 'tail'. Nudibranchs are quite resilient, and unless something very vital is missing, they can survive damhge like this quite well, often regrowing the lost parts.
March 4, 2003
From: Vinka Stenhouse
This is another older image that I thought may be of interest. It was seen at a depth of 22m at Santo, Vanuatu in 1997.
email@example.comStenhouse, V., 2003 (Mar 4) Thecacera picta from Vanuatu. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9196
We now have records of Thecacera picta on the Forum from quite a few parts of the western Pacific and the Maldives in the Indian Ocean. I have updated the distribution details in the Fact Sheet to reflect this new information.
December 7, 2001
From: Erwin Köhler
Erwin@medslugs.deKöhler, E., 2001 (Dec 7) Re: Thecacera vittata from the Maldives. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5791
Every little bit of information is valuable but often we never hear of these observations because they are 'big' enough to justify publication in a scientific journal.
December 6, 2001
From: Erwin Köhler
Attached are 2 shots from the Maldives, South Male Atoll, Vagali Island, divesite "Vagali Caves", length 24 mm, depth 16 m, 22 Sept. 2000.
I thought this one to be Thecacera picta, but today I read the description of Thecacera vittata by Nathalie Yonow, 1994 (Revue fr. Aquariol., 20, (1993): 4, 25 juillet 1994) and I think this is what she described. Is this species valid or is it just a variant of T. picta?
Erwin@medslugs.deKöhler, E., 2001 (Dec 6) Thecacera vittata from the Maldives. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5771
I sometimes wish the urge to describe new species wasn't quite as strong. Considering how little we knew about the colour variation of Thecacera picta, I would have thought that it was not a good idea for Nathalie Yonow to describe a new species on 2 colour slides. The main differences she notes between her species and T. picta were that T. picta had brown bands and not spots, and T. vittata had white markings and T. picta did not. Even from the photos we now have on the Forum you can see that both these characters are extremely variable. I am sure T. vittata is a synonym of T. picta.
I guess from the proximity of the bryozoan colonies, we can be reasonably confident that that is what it feeds on.
December 16, 2000
From: Mary Jane Adams
To add to Bruce Potter's message, every time I have visited the Solomon Islands over the last decade I have seen at least one Thecacera picta on the shallow reef or coral rubble surrounding the wreck of the Ann. This divesite is near the south end of Sunlight Passage in the Russell Island Group. I came across a trio of them in Nov., 2000 at a depth of 13 meters (Upper Photo). When I first saw them, the slug on the right was crawling toward the happily copulating couple. I shot this picture just as the intruder interrupted the action. After failing to join in, the scorned third party crawled away in defeat. The only other place I have seen Thecacera picta was once in Papua New Guinea. It was at about 20 meters on a coral reef on the south side of New Britain Island in Feb., 1995 (Lower Photo)
I hope this information is useful.
firstname.lastname@example.orgAdams, M.J., 2000 (Dec 16) Re: Thecacera picta - Three's a crowd. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3377
Thanks Mary Jane,
Any information on these animals helps build a better understanding of ther distribution and biology.
December 15, 2000
From: Bruce Potter
This is just another entry to extend your listed distribution range. I have found Thecacera picta in the Russell Islands, and the Florida Islands, and at Honiara. All in the Solomon Islands.
This particular one was at Bonegi 1 dive site near Honiara, found at about 20 meters.
email@example.comPotter, B., 2000 (Dec 15) Thecacera picta from the Solomon Ids. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3375
There is not much known about this species so photos showing colour variation and locality information are always welcome.
July 15, 1999
From: Jim Cruise
Here is the photo I promised of Thecacera picta from Queensland.
The details are: Hardy Reef Pontoon, Great Barrier Reef, 19 degrees 46'S, 149 deg 11' E., 36m, March 1995, 19mm long. PHOTO: Jim Cruise.
firstname.lastname@example.orgCruise, J., 1999 (Jul 15) Thecacera picta from Great Barrier Reef. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1071
June 8, 1999
From: Jim Cruise
Confirming message from Jackie Sheils, that this species is common at Hardy reef (Whitsunday). I took several slides of one in about 1995. Richard Willan has a copy as he identified for me.
If you desire a copy let me know.
email@example.comCruise, J., 1999 (Jun 8) Re: Thecacera picta from Great Barrier Reef. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/930
Thanks for the feedback on Thecacera picta. Yes I would very much like a copy of your photo from the Whitsundays.
May 3, 1999
From: Jacquie Sheils
Just a note to let you know that Thecacera picta is very common where I work at Hardy Reef, about 80km NE of the Whitsunday Islands.
We see them regularly at depths of about 20m on sand and rubble slopes at the edge of Hardy Reef. At times there appear to be aggregations of them converging on one area, no doubt for sexual purposes!
firstname.lastname@example.orgSheils, J., 1999 (May 3) Thecacera picta from Great Barrier Reef. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/827
I would love some photos of this animal from the Whitsundays as I don't know of any records of Thecacera picta from that region.
Concerning 'breeding' aggregations. There is a lot of debate about why we find aggregations of Sea Slugs. What we do know is that most mature Sea Slugs will mate, or attempt to when they meet. I guess this is a survival strategy for animals which can't see each other and may only cross paths infrequently. It is possible that in species with very specialised diets, aggregations occur because they are all attracted to a colony of their favourite, but perhaps, uncommon food.
Most Sea Slugs hatch as free-swimming veliger larvae which spend some time in the plankton before settling down on the bottom and growing into crawling slugs. In many cases, it appears that chemicals from their adult food trigger the larvae to stop swimming and to settle down. Having planktonic larvae ensures that, in most species, each generation is spread far and wide.
Some species however have what is called 'direct development' where the slug no longer has a free-swimming larval stage and hatches straight from its egg mass as a tiny crawling slug. In these species, the egg masses are often laid on, or very near, their food, which means that the young often start life in an aggregation and usually stay together until the food runs out. These species often grow very quickly, so unless observations are made very frequently, it may appear that a group of slugs has just 'moved in' when in fact they have always been there but have grown to visible size very quickly.
It's a bit difficult to make a guess at whether, or why, Thecacera aggregates. I suspect it feeds on a bryozoan (lace coral) colony but as with many Sea Slugs, until we know more about their basic natural history it's difficult to say anything sensible about them.
Any photos and/or observations on the feeding, breeding, egg-laying etc of Thecacera, or any Sea Slugs for that matter, would be very welcome.
November 13, 1998
From: Clay Bryce
I thought these pictures [see top of page]of Thecacera picta from Western Australia may be of interest. Nathalie Yonow's species T. vittata seems to be a synonym falling within this colour range. I have other shots showing a range of pattern variation.
All the best,
Western Australian Museum
email@example.comBryce, C., 1998 (Nov 13) Colour variation in Thecacera picta. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/302
Anyone got any comments? As with the discussion we are having about the range of colour variation in Thorunna florens , this is another example of how valuable it is to build up information about colour variation both within a geographic locality and throughout the range of a "species". .. Bill Rudman.