California, USA., Baja California, Mexico.
Pt. Loma, 75ft, San Diego, California, USA. Photo: Sean Kearney
Elongate, aeolidiform in shape with 4 to 7 pairs of characteristic cerata. The cerata consist of consist of between 4-16 finger-like processes arranged side by side. In the lower half they are merged together but the upper part of the processes are free giving each ceras the look of a multi-fingered hand. The oral lobes on each side of the head are of similar shape to the cerata. The rhinophores are typically dendronotoidean in shape with the actual rhinophore sitting in a smooth-edged cup-shaped sheath. The colour appears to be somewhat variable. The body basically translucent or nearly transparent with varying amounts of brown and white pigmentation in different animals. Grows to 15mm in length.
Probably feeds on hydroids.
• Behrens, D., (1991) Pacific Coast Nudibranchs.
• MacFarland, F.M. (1923) The morphology of the nudibranch genus Hancockia. Journal of Morphology, 38(1): 65-104, Pls 1-6.
• MacFarland, F. M. (1966) Studies of opisthobranchiate mollusks of the Pacific coast of North America. Memoirs of the California Academy of Sciences, 6: 1-546, pls. 1-72.
Rudman, W.B., 2004 (February 19) Hancockia californica MacFarland, 1923. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/hanccali
December 1, 2009
From: Kevin Lee
Here are some Hancockia californica specimens, found by Alicia Hermosillo, at Isla Marieta and Los Arcos, respectively.
Locality: Puerto Vallarta, 25fsw, Mexico, East Pacific, 05 July 2009, Rocky, sandy reef, with UW flora. Length: 1/2 inch and 1/4 inch . Photographer: Kevin Lee.
email@example.comLee, Kevin, 2009 (Dec 1) Hancockia californica from Mexico. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22900
Thanks for these photos. Perhaps Alicia could explain the peculiar shape of the cerata in the upper photos. I can't see any sign of the 'fingers' which are usually a characteristic part of the cerata of Hancockia. In the closeup I can see branches of the digestive gland going out to the edge but no sign of the 'fingers' they should extend into. Have the 'fingers' been bitten off or have they all merged to form large solid cerata, or are the 'fingers' just contracted?
Also in the second animal [lower photo] the 'fingers' are branched. Is this perhaps a Dendronotus?
December 1, 2009
From: John K. Yasaki
Concerning message #21337:
As per my previous message (#22515), this is the second trio of images of Hancockia californica from Pacific Grove, California.
Locality: Lovers Point; Pacific Grove, 35 to 40 fsw, California, USA, Monterey Bay; Pacific Ocean, 31 May 2009, Rocky Reef. Length: 9 to 19 mm (3/8 to 3/4 inch) . Photographer: John Yasaki.
The upper two photos show a pair, which I suspect are mating with a voyeur (Dendronotus frondosus, I believe)
Yasaki, John K., 2009 (Dec 1) More pics of Hancockia californica. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22516
The pair may have been mating but if so, they have been disturbed by the Dendronotus, because their heads would need to be about halfway down the other's body for them to be correctly aligned. I have also included a closeup showing a colony of living hydroid polyps at the bottom and the white lines at the top which I suspect are the remains of a hydroid colony after the polyps have been grazed by Hancockia.
December 1, 2009
From: John K Yasaki
Concerning message #21337:
Found a large number of these critters on red algae (Palmaria mollis?) off Lovers Point in Pacific Grove, California. I'm attaching several images; feel free to weed out any you find redundant or whatever. Lengths of the animal in these images I would approximate as 3/8 to 3/4 inches.
Locality: Lovers Point; Pacific Grove, 35 to 40 feet, California, USA, Monterey Bay; Pacific Ocean, 31 May 2009, Rocky Reef. Length: 3/8 to 3/4 inch (9 to 19mm). Photographer: John Yasaki.
These photos show a single animal and two that seem to be egg-laying. In a second message [#22516] I have more photos including two showing mating.
Yasaki, J. K., 2009 (Dec 1) Hancockia californica from Pacific Grove, California. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22515
Your photos give us a few more vieiws of the strange 'handlike' cerata these animals have. I presume they are eating hydroids living on the algae. The traces of a white network we can see on the algae are, I guess, the remains of hydroid colonies.
February 5, 2008
From: Bernard Picton
Concerning message #12295:
Just looking to see what you had on Hancockia as Steve Trewhella just found some on a box which had been cast up on the shore in Dorset, south coast of England, together with Goose barnacles and hydroids. I've only found Hancockia uncinata on a few occasions, but it seems to feed on the hydroid Clytia hemisphaerica. I don't know the Californian hydroid fauna, but the one that Hancockia californica is feeding on has very similar morphology to Clytia hemisphaerica and I would guess that it is also a species of Clytia.
firstname.lastname@example.orgPicton, B. E., 2008 (Feb 5) Re: Hancockia californica feeding. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21337
Someone sent me an email recently asking why I still had a message of theirs on the Forum from 5 years ago and could I remove it because it was out of date. Your reference to Sean Kearney's 4 year old message is a good example showing why nothing on the Forum is 'out of date'. Facts and photos certainly don't become invalid through age and having a record of opinions and identifications changing over time as more information becomes available is very instructive in reminding us that we are not infallible.
Hopefully someone in California may be familar enough with the local hydroids to confirm your suggested identification. As you will have seen H. uncinata has not made the Forum yet so if you or Steve Trewhella has any photos of his recent find they would be welcome.
May 29, 2007
From: Clinton Bauder
My dive club was privileged to host Alicia Hermosillo for 3 days of diving in the Monterey area. She was able to find several species that were new to me. This is Hancockia californica.
Locality: Monterey, 15 meters, CA, USA, Pacific, 20 May 2007, Shale beds off of Del Monte Beach. Length: 15mm. Photographer: Clinton Bauder.
Bauder, C., 2007 (May 29) Hancockia californica from Monterey, CA. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19949
Spectacular close ups showing the key (important) identifying characteristics of this somewhat uncommon species. It takes eyes like Ali's has to find these guys.In your photos we can clearly see the palmate (hand shaped) morphology of the cerata and frontal veil. This is in contrast with the morphology of these features in Dendronotus, where they are highly branched and which are constantly confused with this species. We can also see that the rhinophores have a very simple, short and blunt crown, and they do not have any lateral processes.
November 30, 2005
From: Jeff Goddard
Here are some images, taken through a dissecting microscope, showing the unusual rhinophores and cerata of Hancockia californica.
Locality: Montana de Oro, California, USA. Length: 7 mm. 26 May 2005. Rocky intertidal. Photographer: Jeff Goddard
email@example.comGoddard, J.H.R., 2005 (Nov 30) Rhinophores and cerata of Hancockia californica. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15368
Thanks for these photos. They certainly help to explain its shape. To those of you not familiar with this animal:
Uppermost photo shows two of the cerata on the right side. They look a bit like a many fingered hand with fingers bent as if to catch a ball.
Middle photo: View of one cerata from the middle of the body looking out.
Lower photo: Rhinophore, with small rhinophore club partly hidden in flower-like sheath.
November 30, 2005
From: Jeff Goddard
Here are some images of the egg mass (2 mm high), uncleaved eggs, and veligers (one day before hatching) of Hancockia californica. The eggs averaged 100 microns in diameter and hatched after 10 days at 12-17 degrees C as planktotrophic veligers with egg-shaped shells averaging 243 microns in length. I rarely see this species, and this was the first time I have been able to observe its egg mass and development.
Locality: Montana de Oro, California, USA. Length: 2 mm (height of egg mass). 30 May 2005. Rocky intertidal. Photographer: Jeff Goddard
Goddard, J.H.R., 2005 (Nov 30) Eggs and development of Hancockia californica. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15369
February 24, 2004
From: Sean Kearney
Thanks for the identification.
Here are a few more pictures of Hancockia californica taken from a different angle. I hope that these will be of some help. As to the size of the critter that I photographed, I believe that it was about 7mm in length. This measurement can be verified by Dave Behrens (I sent him the specimen).
Thanks again for a wonderful site.
firstname.lastname@example.orgKearney, S., 2004 (Feb 24) Re: Hancockia californica. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12295
Thanks for this extra photo. You can see one of the rhinophores with the cup-shaped sheath and one of the finger-like oral 'tentacles' much like the ones on Bornella.
It is also a spectacular view of the hydroid colony, You can see the root-like stolons forming a network over the rock, the individual polyp animals on long thin stalks and the fat gonotheca which are the specialised reproductive polyps which form the free-swimming medusoid generation of these strange plant-like animals.
February 23, 2004
From: Sean Kearney
I have tried to get this creature identified locally, but am not getting any feedback. I am sorry that I cannot provide any better photographs, however I do have some from different angles if needed. Photo was taken topside due to the strong surge at the 75 fsw depth. Under close examination the red "spots" are really lines with sharp angles. Black dots and white encrustation. Any idea of the species? I wondered if it was Dendronotus?
75ft, San Diego. Pt. Loma. [California]Thanks for a great site, and for all of your information.
Kearney, S., 2004 (Feb 23) Hancockia californica from California. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12269
This is a nice addition to the Forum. It's Hancockia californica, which is related to Dendronotus but differs in having these strange hand-like cerata. I can't find any reference to what this species feeds on but if you have photographed it on the rock you found it on, or under, then it looks like it was in a banquet of hydroids. The European species Hancockia uncinata feeds on hydroids
If you can give me an idea of its size, and if you have any photos showing its head more clearly I would be grateful