Dendronotus rufus
O'Donoghue, 1921

Order: NUDIBRANCHIA
Suborder: DENDRONOTINA
Family: Dendronotidae

DISTRIBUTION

Known from Auke Bay, Alaska to Seattle, Washington (Behrens & Hermosillo, 2005)

PHOTO

Whidbey Island, Puget Sound. Washington,  USA. Depth: 30 feet. Length: 6 inches. 04 January 2005. artificial reef. Photographer: Jan Kocian

Large Dendronotus, growing to about 30 cm in length. In most specimens the body is translucent white, with some fine magenta red spotting, and a red line around the border of the foot. The tips of the branched cerata are magenta red. There is a rare 'red form'  in which the body is completely red except for a scattered translucent white spots and patches.

There are six to nine pairs of cerata [usually 7 or 8] and they are the largests and most finely brached of any species of Dendronotus. Between the ceratal rows there can be accessory 'cerata' or bushy outgrowths similar in colour and about the size of the smallest 'true cerata'. The rhinophore stalk is as large as the first cerata, and extensively branched. Similarly the five pairs of papillae along the edge of the oral veil are long and branched. In Robilliard's extensive studies (1970) he could not determine the food of this species although its stomach contenets suggested it may at times feed on the scyphistoma stage of some jellyfish.

  • Behrens, D. W. and Hermosillo, A. (2005) Eastern Pacific Nudibranchs. A Guide to the Opisthobranchs from Alaska to Central America. Monterey, California, Sea Challengers.  1-137.
  • O'Donoghue, C. H. (1921) Nudibranchiate Mollusca from the Vancouver Island region. Transactions Royal Canadian Institute, 13: 147-209.
  • Robilliard, G. A. (1970) The systematics and some aspects of the ecology of the genus Dendronotus. The Veliger, 12: 433-479, pls. 63-64.
Authorship details
Rudman, W.B., 2006 (January 31) Dendronotus rufus O'Donoghue, 1921. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/dendrufu

Related messages


Dendronotus rufus - egg predation 3

April 30, 2007
From: Jan Kocian


Hello Bill.
Following on from my earlier messages [#19289] I thought I should update you on the lives of Dendronotus rufus at the Langley Tire Reef. They are still there in numbers, about two dozen slug busily engaged in egg laying. I check on them weekly, they like to choose a rock and cover it with eggs, then move to another one and start all over again.

Interestingly, since I first discovered them on January 10th, they remain in the same two areas, never venturing more the fifteen feet diameter from the egg covered rocks. On my last visit I found small Pycnopodia star on one of the egg spirals, and watched D. rufus crawl on top of the star which then rapidly departed, leaving eggs intact. Could it be that D. rufus engaged the star in chemical warfare?

Locality: Whidbey Island,Puget Sound, 18 feet, Washington, USA, Eastern Pacific Ocean, 1 March 2007, rocks. Length: 170 mm. Photographer: Jan Kocian.

Cheers,
Jan

honkoc@hotmail.com

Kocian, J., 2007 (Apr 30) Dendronotus rufus - egg predation 3. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19592

Dear Jan,
Sorry this has taken a while to post. It certainly looks as though one of the Dendronotus gave the starfish a message it decide not to ignore, and a chemical one is probably the most likely. I can't recall any studies on chemical defence in dendronotids but we still have a lot to learn.

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Apr 30). Comment on Dendronotus rufus - egg predation 3 by Jan Kocian. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19592

Dendronotus rufus - egg predation [2]

February 9, 2007
From: Jan Kocian

Hi Bill.
And here are some more pictures of the Dendronotus rufus laying eggs  to accompany my earlier message [#19288 ].

Locality: Whidbey Island, Puget Sound, 18 feet, Washington, USA, Eastern Pacific Ocean,, 19 January 2007, rocks. Length: 170 mm. Photographer: Jan Kocian.

Jan Kocian

honkoc@hotmail.com

Kocian, J., 2007 (Feb 9) Dendronotus rufus - egg predation [2]. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19289

Thanks Jan,
Bill Rudman

Rudman, W.B., 2007 (Feb 9). Comment on Dendronotus rufus - egg predation [2] by Jan Kocian. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19289

Dendronotus rufus eggs - starfish predation

February 9, 2007
From: Jan Kocian


I found a congregation of Dendronotus rufus on rocks beneath a seawall, some were laying eggs. The area is overrun by the starfish Pycnododia
helianthodes and I spotted some of the D. rufus eggs under one of the sea stars. I peeled the star off and found another star also involved in the undesirable activity.

Locality: Whidbey Island,Puget Sound, 18 feet, Washington, USA, Puget Sound, NE Pacific Ocean, 19 January 2007, rocks. Length: 170 mm. Photographer: Jan Kocian.

Jan Kocian

honkoc@hotmail.com

Kocian, J., 2007 (Feb 9) Dendronotus rufus eggs - starfish predation. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19288

Dear Jan,
Thanks for the interesting record - and for the photos of D. rufus. We don't have many records of predation on nudibranch eggs, apart from aeolids of the genus Favorinus, so any new observations are welcome. Thanks also for the cartoon of the brave diver trying to save the eggs

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Feb 9). Comment on Dendronotus rufus eggs - starfish predation by Jan Kocian. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19288

Re: Dendronotus rufus? from Alaska

December 11, 2006
From: Gordon Robilliard

Concerning message #18740:

These are almost certainly D. rufus. The greyish body with maroon cerata tips is a good trait. The maroon may be more or less intense, though I have no idea why. From my recollection (30+ years ago), there was not any obvious geographic gradient in color intensity. As a side note, occasionally one might find speciments that are almost entirely maroon even on the body. This is reminiscent of the reddish/orange body color of a few D. iris. Again I have no idea why the color variants unless it is a genetic aberration or some genetic recessive expressing itself.

Dave Behrens comment about possibly being D. frondosus has some merit in that D. frondosus is one of the most diverse of the NE Pacific Dendronotus with regard to color patterns. They are also fairly polymorphic in size, cerata, and veil papillae. (Maybe they are actually subspecies though I never investigated this possibility).

Gordon Robilliard

grobilliard@entrix.com

Robilliard, G. A., 2006 (Dec 11) Re: Dendronotus rufus? from Alaska. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/18977

Dear Gordon,
It's good to hear from you after so many years. I look forward to further contributions

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Dec 11). Comment on Re: Dendronotus rufus? from Alaska by Gordon Robilliard. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/18977

Dendronotus rufus? from Alaska

December 5, 2006
From: Bradley Stevens

Here is a mating orgy of several Dendronotus rufus, on a piling in Women's Bay, Kodiak, Alaska, approx 20 feet deep.

Locality: Womens Bay, 20 ft, Kodiak, Alaska, USA, North Pacific, on wood piling. Photographer: Dr. Bradley Stevens.

Bradley Stevens

bstevens@umassd.edu

Stevens, B., 2006 (Dec 5) Dendronotus rufus? from Alaska. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/18740

Hi Brad,

Thanks for this note. Interesting behavior, but I am not positive about your ID. I think we will ride with yours for now but this might be Dendronotus frondosus. And, the white specks suggest maybe even my Dendronotus sp. 1 bottom of page 95 in Eastern Pacific Nudibranchs.

Incidently a colleague at the LA County Museum is looking at the genus closely and needs specimens of these northern species. Is it possible to collect a few and drop them in 70% ethanol. Let me know

Thanks,
Dave Behrens

Behrens, D.W., 2006 (Dec 5). Comment on Dendronotus rufus? from Alaska by Bradley Stevens. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/18740

Dendronotus rufus from Puget Sound

February 1, 2006
From: Jan Kocian


Hi Bill,
looking through the Forum database, I did not see Dendronotus rufus, so I dug some out of my dive log.

Locality: Whidbey Island, Puget Sound. Washington,  USA. Depth: 30 feet
Length: 6 inches. 04 January 2005. artificial reef. Photographer: Jan Kocian

At least I hope that it is D. rufus.
Jan

honkoc@hotmail.com

Kocian J., 2006 (Feb 1) Dendronotus rufus from Puget Sound. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14976

Dear Jan,

Ever since you showed me your photos of Dendronotus rufus, I have been kicking myself, for not meeting you earlier.  Your photos belong in both Behrens & Hermosillo (2005) and Behrens (2005).  Your photos clearly show the extreme branching of the cerata, lateral rhinophoral processes and frontal veil.

Now, please tell us what these guys were feeding on up at Whidbey Island.  Thanks.

  • Behrens, D.W. & A. Hermosillo.  2005.  Eastern Pacific Nudibranchs - A guide to the opisthobranchs from Alaska to Central America.  Sea Challengers.   137 pp.
  • Behrens, D.W.  2005.  Nudibranch Behavior.  New World Publications Inc. Jacksonville, Florida. 176 pp.

Best wishes,
Dave Behrens

Behrens, D.W., 2006 (Feb 1). Comment on Dendronotus rufus from Puget Sound by Jan Kocian. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14976