Thecacera pacifica
Bergh, 1883

Order: NUDIBRANCHIA
Suborder: DORIDINA
Superfamily: ANADORIDOIDEA
Family: Polyceridae
Subfamily: Polycerinae

DISTRIBUTION

Indian Ocean & Western Pacific

PHOTO

AM C132433, 25 mm long alive. 17 October 1981, underneath loose rock, 12 m, Christmas Is., Indian Ocean. Photo: John Hicks

Reference:
• Bergh, R. (1883). Beiträge zu einer Monographie der Polyceraden. Verhandlungen der Koniglich-kaiserlich Zoologische-botanischen Gesellschaft in Wein (Abhundlungen), 33: 135-180, pls 6-10

Authorship details
Rudman, W.B., 2002 (April 23) Thecacera pacifica Bergh, 1883. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/thecpaci

Related messages


Thecacera pacifica from Mozambique

January 13, 2009
From: Valda Fraser

Dear Bill
I think this nudibranch is Thecacera pacifica. It would be great to have confirmation from you.

Locality: Pomene, 8 m, Mozambique, Indian, 16 Dec 2008, Rocky reef. Length: 15 mm. Photographer: Valda Fraser.

Thanks.
Valda

valdafraser@mweb.co.za

Fraser, V.J., 2009 (Jan 13) Thecacera pacifica from Mozambique. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22140

Dear Valda,
It is nice to get a photo of an animal from Mozambique as there are very few records of this species from the western Indian Ocean. As I mentioned in an earlier message [#21894], Macnae found many specimens of this species at Inhaca Island in sthn Mozambique and unnecessarily named it T. inhacae.

Best wishes,
Bill Rudman

Rudman, W.B., 2009 (Jan 13). Comment on Thecacera pacifica from Mozambique by Valda Fraser. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22140

Thecacera pacifica - egg laying from Reunion

September 19, 2008
From: Philibert Bidgrain

Concerning message #9514:

Dear Bill,
Reunion Island seaslug

We have found these two strange specimens of Thecacera pacifica with black and white stripes. In the upper photo you can see the spawn, similar to that illustrated by Michael Miller [message #9514 ].

Locality: Longoni Harbourg, Mayotte Island, Indian Ocean, January 2008. Photographer: Emmanuel Eby.

Do you think that is a new colour variation for this species?

All the best
Philibert Bidgrain
http://vieoceane.free.fr/runseaslug/indexslug.htm

pbidgrain@yahoo.fr

Bidgrain, P., 2008 (Sep 19) Thecacera pacifica - egg laying from Reunion. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21894

Dear Philibert,

Thanks for these photos. I can't recall seeing specimens with these extra black & white stripes on the body, but I would agree that this is almost certainly just a colour variant of T. pacifica. The only records I know from the western Indian Ocean are from Mozambique where Macnae (1958) described it unnecessarily as a new species, Thecacera inhacae. Macnae reported examining a 'large number of specimens' but all his animals apparently had the normal unstriped colour pattern. Gosliner (1987) reports a single specimen from Knysna, South Africa which also lacks stripes.

  • Macnae,W. (1958) The families Polyceridae and Goniodorididae (Mollusca, Nudibranchiata) in southern Africa. Transactions of the Royal Society, South Africa, 35(4): 341-372. (Pls.17-18)
  • Gosliner, T. M. (1987) Nudibranchs of Southern Africa, a guide to the Opisthobranchs of southern Africa. Monterey, Sea Challengers.  1-136.

Best wishes,
Bill Rudman

Rudman, W.B., 2008 (Sep 19). Comment on Thecacera pacifica - egg laying from Reunion by Philibert Bidgrain. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21894

Re: Thecacera pacifica - sensory organ

March 15, 2006
From: Roberto Sozzani

Concerning message #11724:

Dear Bill,
Thank you very much for the explanation, there is always something to learn!

I must add I was very surprised (and happy too) to see this message: it was from December 2003 and I had almost forgotten it. This confirms how many queued messages you have to deal with, but it's also a reassurance that nothing is lost in your archive, only waiting for the right time.

So, thanks again for your great work!
Roberto Sozzani

roberto.sozzani@fastwebnet.it

Sozzani, R., 2006 (Mar 15) Re: Thecacera pacifica - sensory organ. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16079

Dear Roberto,
Sorry for the delay, but hopefully the recent upgrading of our editing systems will help me 'rummage' more efficiently through the backlog.
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Mar 15). Comment on Re: Thecacera pacifica - sensory organ by Roberto Sozzani. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16079

First record of Thecacera pacifica from Caribbean!

March 10, 2006
From: Joyce Burek

Have there been any reports of Thecacera pacifica in the Caribbean or Gulf of Mexico. I photographed them March 3rd at Stetson bank in the Flower Garden Banks NMS in the Gulf of Mexico at a depth of 98 ft.

Locality: Stetson Bank of Flower Garden banks NMS, 98 ft., Texas, USA, Gulf of Mexico, 03 March 2006, hydroid covered bottom. Length: 1.5 inches.. Photographer: Joyce Burek.

Joyce Burek

jfburek@consolidated.net

Burek, J.W., 2006 (Mar 10) First record of Thecacera pacifica from Caribbean!. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16063

Dear Joyce,
As far as I know this is the first record of Thecacera pacifica from the Atlantic, all previous records being from the tropical Indo-West Pacific. I have also looked through earlier records from the Atlantic and can find no similar animal being reported under any name. I can only assume that like quite a few other polycerids [including Polycera hedgpethi, Polycera capensis, Thecacera pennigera] this species makes use of shipping to travel far from its home territory.

Since most nudibranchs have very specialised food requirements, successful translocations like this are dependent on suitable food being present in the new locality. In some cases the food is also a 'tramp' species, but in other cases it appears that a local species, often closely related to the 'real' food species, can be used. It is possible that the bright orange bryozoan colony at the bottom of your photo is the food of Thecacera.

It looks as though your two animals are mating. This could well mean that the Caribbean has a new permanent member of its fauna.
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Mar 10). Comment on First record of Thecacera pacifica from Caribbean! by Joyce Burek. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16063

Thecacera pacifica - sensory organ

March 10, 2006
From: Roberto Sozzani

Dear Bill,
I notice you don't have many records of this species. Here is a photo which shows, in transparency, the circular mouth of this species. I hope this can be of interest for you.

This species was very common in Sangeang Island (Indonesia) on a black sandy slope starting at 22 meters, at the base of a very fragile sand and coral wall. But Sangeang has an active volcano, so the wall is almost all fallen down now and many species disappeared.

Location: Sangeang Island, Indonesia. Depth: 22 meters, Size: 3-4 cm. August 2001. Photos: Roberto Sozzani

Roberto Sozzani

roberto.sozzani@fastwebnet.it

Sozzani, R., 2006 (Mar 10) Thecacera pacifica - sensory organ. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11724

Dear Roberto,
The structure which looks like a mouth is very interesting. It is in fact a sensory organ which this species has on either side of the head just below the rhinophores. Quite a few polycerids, but not all, have similar organs, but as the organ is a groove which is often closed, it is seldom noticed. If you look in other photos of the species in the Forum you will see this organ as a little whitish line just below the rhinophores. In preserved polycerids it is often invisible. Have a look at my message about similar organs in Tambja morosa [#10513].

Thank you very much for sending this photo. I made some pencil sketches of this organ in Thecacera some years ago, but this is the first time I have seen a photo of it.

Best wishes
Bill Rudman

Rudman, W.B., 2006 (Mar 10). Comment on Thecacera pacifica - sensory organ by Roberto Sozzani. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11724

Thecacera pacifica from Bali

December 17, 2005
From: Erwin Kodiat

Hi Bill,
I got this Thecacera pacifica in Tulamben Drop Off, Bali.

Locality: Tulamben, Drop Off, Bali, Indonesia. Lombok Strait. Depth: 7 meters. Length: 2 cm. 13 November 2005. Rocky. Photographer: Erwin Kodiat

Erwin Kodiat

ungu@terong.com

Erwin Kodiat, 2005 (Dec 17) Thecacera pacifica from Bali. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15443

Thanks Erwin,
Best wishes,
Bill Rudman

Rudman, W.B., 2005 (Dec 17). Comment on Thecacera pacifica from Bali by Erwin Kodiat. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15443

Pikachu was inspired by this?

December 20, 2003
From: Parvita Siregar


Dear Bill,
During my dive around the Komodo Island, Indonesia, my eyes caught this cute nudibranch. There was no current. I thought this nudibranch looked like Pikachu, the Japanese pocket monster character :-) Which species does this belong to?

Site: Pink Beach, Komodo Island
Date: 22 August 2003
Depth: 12 meters
Size: 1.5 to 2 cm

Parvita Siregar

parvita.siregar@eniindonesia.co.id

Siregar, P., 2003 (Dec 20) Pikachu was inspired by this?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/10903

Dear Parvita,
I'm afraid I am not an expert on Japanese monsters so can't comment on its likeness to Pikachu. Its name is Thecacera pacifica. There are not many records of this species so yours is a welcome addition
Best wishes
Bill Rudman

Rudman, W.B., 2003 (Dec 20). Comment on Pikachu was inspired by this? by Parvita Siregar. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/10903

Thecacera pacifica - egg laying

March 31, 2003
From: Michael Miller


Dear Bill,
During our 1998 trip to Tulamben, Bali, Indonesia we were fortunate to have a number of Thecacera pacifica in residence. Here is a "tub" shot showing the animal in the process of laying an egg mass. In a second message I have posted photos of it mating.

Location: Tulamben, Bali, Indonesia, Oct. 1998. Photographer: Michael D. Miller

Cheers,
Michael D. Miller

mdmiller@cts.com

Miller , M., 2003 (Mar 31) Thecacera pacifica - egg laying. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9514

Thanks Mike,
I don't think I have seen its egg ribbon before.
Bill Rudman

Thecacera pacifica - mating

March 31, 2003
From: Michael Miller

Dear Bill,
To accompany my other message of Thecacera pacifica egg-laying, here are photos of Thecacera pacifica your readers may find of interest. These are in situ shots, and the upper right photo shows them mating, and the enlarged lower right photo reveals details of the copulatory apparatus.

Location: Tulamben, Bali, Indonesia, Oct. 1998. Photo: Michael D. Miller

Cheers,
Michael D. Miller

mdmiller@cts.com

Miller , M., 2003 (Mar 31) Thecacera pacifica - mating. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9515

Thanks Mike,
Bill Rudman

Thecacera pacifica from Vanuatu

February 28, 2003
From: Vinka Stenhouse

Bill,
I've gone through some of my older slides and found this one which may be of interest. This Thecacera pacifica was seen on a pier pylon at a depth of 4 metres at Santo, Vanuatu in 1994.
Regards,
Vinka

vinkas@oceanaphotography.com

Stenhouse, V., 2003 (Feb 28) Thecacera pacifica from Vanuatu. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9195

Dear Vinka,
Thanks for this great photo of a rarely found animal
Best wishes,
Bill Rudman

Thecacera pacifica from Christmas Island

April 30, 2002
From: W.B. Rudman


Here is a second record of Thecacera pacifica from John Hicks' Christmas Island, Indian Ocean collections.

This specimen is

PHOTOS:
AM C126500, 15 mm long alive. 13 November 1980, south arm of Cantilever, 7.5m, on coral rock, Christmas Is., Indian Ocean. Photo: John Hicks

Best wishes,
Bill Rudman

Rudman, W.B. , 2002 (Apr 30) Thecacera pacifica from Christmas Island. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6564

Thecacera pacifica from Christmas Island

April 27, 2002
From: W.B. Rudman


Here is a reord of Thecacera pacifica from John Hicks' Christmas Island collections.

AM C132433, 25 mm long alive. 17 October 1981, underneath loose rock, 12 m, Christmas Is., Indian Ocean. Photo: John Hicks

Best wishes,
Bill Rudman

Rudman, W.B. , 2002 (Apr 27) Thecacera pacifica from Christmas Island. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6614