Dendronotus iris
Cooper, 1863
Order: NUDIBRANCHIA
Suborder: DENDRONOTINA
Family: Dendronotidae
DISTRIBUTION
West coast of North America from Alaska to Baja California.
PHOTO
Animal feeding on Pachycerianthus fimbriatus at Chup Point in Barkley Sound, British Columbia, Canada, 40 feet of water on sandy bottom with many Pachycerianthus, 27 November 2000. Photo: Ray Izumi
The colour of the body is highly variable, ranging from translucent white or gray, to orange or red. There can also be white spots or scattered brownish patches. One distinctive feature is that the stalk of the rhinophore sheath has a vertical row of three to six small branched processes on its posterior side. Another distinctive feature is that the foot is edged in white, although it seems that this can be partially absent in some animals. The oral veil has four paired processes. The branching gills can be tipped with white, orange, yellow, or purple. Dendronotus iris feeds on the burrowing anemone Pachycerianthus fimbriatus. It can grow to about 30cm but is usually one third that length.
References:
• Cooper, J. G. 1863. On new or rare Mollusca inhabiting the coast of California. No. II. Proceedings of the California Academy of
Natural Sciences, 3: 56-60.
• Robilliard, Gordon A. 1970. The systematics and some aspects of the ecology of the genus Dendronotus. The Veliger, 12(4): 433-479.
• Wobber, Don R. 1970. A report on the feeding of Dendronotus iris on the anthozoan Cerianthus sp. from Monterey Bay, California. The Veliger, 12(4): 383-387, pls. 55-57.
Related messages
Dirona albolineata eggs?
August 6, 2007
From: Jackie Hildering
I am not positive about these as I have yet to see an animal lay the mass but believe that these are the masses of Dirona albolineata. Although both Dendronotus iris and Dirona albolineata are prominent on this site and that the eggs could be those of D. iris at a different stage of maturity, I more often find these more transparent masses on brown algae like Agarum fimbriatum and occasionally, fairly loose on a sandy bottom (like the one photo I have included). Any insights into discerning the eggs masses of Dirona albolineata, Dendronotus iris and Dirona pellucida would be greatly appreciated!
Locality: Bear Cove - Port Hardy, 30 to 45 feet, British Columbia, Canada, Pacific Ocean, 09 April 2007 , mud bottom. Length: 16 cm. Photographer: Jackie Hildering.
Jackie Hildering
earthlingenterprises@telus.net
Hi Jackie,
I usually avoid the identification of lone egg masses at all costs unless they are very characteristic. These however, as you mention, are not. But keep in mind you are trying to ID the eggs of species belonging to two completely different suborders, Dendronotina and Arminina.
The size alone, of your mass suggest D. iris. Your mass also agrees with this species as described in Hurst (1967). She describes the mass of Dirona as "untidy in appearance and superficially similar to that of Aeolidia." The mass in your photo seems quite "tidy" to me. She also describes the mass of Dirona aurantia as being salmon-pink in color.
-
Hurst, A. 1967. The egg masses and veligers of thirty Northest Pacific opisthobranchs. The Veliger 9(3): 255-288.
Hope this helps,
Dave Behrens
Dendronotus iris eggs?
July 7, 2007
From: Jackie Hildering & Glen Miller
I am fairly certain that these are the egg masses of Dendronotus iris since this animal being prolific at this site and that one would expect them to spawn at base of their favourite snack, the tube dwelling anemone (Pachycerianthus fimbriatus).
Locality: Bear Cove - Port Hardy, 40', British Columbia, Canada, Pacific Ocean, 9 April 2007, Silt bottom. Length: 30 cm. Photographer: Jackie Hildering .
Jackie Hildering and Glen Miller
earthlingenterprises@telus.net
Dear Jackie and Glen,
You are absolutely correct. I have also thought it most interesting that the nudibranch often lays it eggs here. Of course many species lay their eggs on the food. Probably because they spend so much time there. In this case we are talking about a fast moving predator that forages widely over the sand bottom in search of anemones with tentacles extended. They then attack violently.
My question would be - did the slug lay them while waiting for the anemone to come out so it could pounce on it, or did the slug lay the eggs after an unsuccessful attack? We may never know.
Thanks for sharing,
Dave Behrens
Dendronotus iris from La Jolla, California
June 10, 2006
From: Regina McLendon
If you're able to ID this little creature I'd so appreciate it as I've looked up all types of nudibranchs and can't find one like this. It's of course a deep orange color with white tips, about 7cm in length and found on the sandy bottom at La Jolla Shores, La Jolla, CA, USA. This photo was taken on a night dive, water temp. around 50 F. There were several other of these that looked to be mating but this is a single picture only. Any info you can give me will be most appreciated.
Locality: La Jolla Shores, about 65 -80 feet, California, USA, Pacific Ocean, 24 May 2006, sand bottom at the Shores near canyon. Length: 7 cm. Photographer: Doug Gueldner.
Thanks,
Regina
reggielamc@aol.com
McLendon, R., 2006 (Jun 10) Dendronotus iris from La Jolla, California. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16812
Hi Regina,
All the divers at "The Shores" are telling me this species is really abundant right now. This is Dendronotus iris. The key distinguishing trait is the white line along the edge of the foot, clearly shown in your photos.
This species feeds on tube anemones. It's quite a sight, or battle, depending on your viewpoint. With the huge population of slugs I am guessing the anemone population is taking a real hit.
Thanks for the great photos,
Dave Behrens
Dendronotus iris feeding behaviour
May 19, 2006
From: Dave Behrens
Concerning message #16629:
Hi Bill:
Concerning the "small?" animal down in the anemone tube - this is quite common. After locating a tube anemone with its tentacles extended the slug rears up and back and attacks the anemone rapidly and hard (see Nudibranch Behavior, pg 96). Almost everytime, the anemone retracts back into the tube, pulling the slug in also. The slug stays within the tube and usually wins the tug of match by continuing to chew on the anemone until it succumbs. Amazing behavior, quite exciting to watch.
Dave Behrens
dwbehrens@comcast.net
Behrens, D.W., 2006 (May 19) Dendronotus iris feeding behaviour. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16642Thanks Dave,
Bill Rudman
Dendronotus iris feeding behaviour
May 19, 2006
From: Phil Garner
Concerning message #16629:
Very few of the D.iris seem to attach their eggs in the sand. Most are atached to the tube anemones themselves. As far as stinging, the nudis climb up the stalk, arch their back and bite the tentacles of the anemone, which retracts into its home. The nudi then crawls out, usually with a tentacle or two in its mouth for a tasty meal. I have seen other nudibranchs, including Cuthona divae laying eggs next to their food source.
Locality: Rancho Palos Verdes, 45-70 feet, California, USA, Eastern Pacific, 02 April 2006, Edge of a rocky reef on or near Pachycerianthus fimbriatus. Length: 1 inch to 10 inches. Photographer: Phil Garner.
Phil Garner
PacificCoast101@cox.net
Garner, P., 2006 (May 19) Dendronotus iris feeding behaviour. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16646Thanks Phil,
Best wishes,
Bill Rudman
Colour forms of Dendronotus iris
May 18, 2006
From: Stephanie Truhlar
Hi Bill,
Here is the Dendronotus iris photo that I posted on Divebums Photos of the Week [see message #16629 ]. I hope that I did this "new message" right!
Locality: La Jolla Shores (North Wall), ~60 ft, California, USA, Pacific, 7 May 2006, sand flat above canyon wall?. Length: ~6 in?. Photographer: Stephanie Truhlar.
Stephanie Truhlar
truhlar@gmail.com
Truhlar, S. M. E., 2006 (May 18) Colour forms of Dendronotus iris. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16634
Dear Stephanie,
Thanks for sharing this this photo which shows two extreme colour forms of D. iris together. Any time you have photos of sea slugs 'doing things' such as mating, feeding, being eaten - or just looking interesting - they would be welcome on the Forum
Best wishes,
Bill Rudman
Re: Dendronotus nanus rediscovered in California
May 18, 2006
From: Phil Garner
Concerning message #14507:
There has been a population explosion of Dendronotus iris at Marineland in Rancho Palos Verdes, California the past month. I have witnessed dozens of them laying eggs and have spotted two that resemble the 'Dendronotus nanus colour form' in the same area. There have also been reports of both 'species' together in La Jolla. I have always wondered if they are the same species with widely variable colorations, but D. iris seems to have appendages compared to the cerata of D. nanus.
Locality: Rancho Palos Verdes, 45-70 feet, California, USA, Eastern Pacific, 02 April 2006, Edge of a rocky reef on or near Pachycerianthus fimbriatus. Length: 1 inch to 10 inches. Photographer: Phil Garner.
I found a great picture from Stephanie Truhler on the DiveBums site. It shows both 'species', or variations of the same species, laying identical eggs side by side.
http://week.divebums.com/2006/May08-2006/Dendronotus-iris_stephanie-truhlar.jpg
Phil Garner
PacificCoast101@cox.net
Dear Phil,
Thanks for the photos. As you will see from other messages, the Californian experts all agree that D. nanus is just a colour form of D. iris. Is it usual for them to lay their egg ribbons on the tubes of their food, as seen in your photos? It would seem a bit dangerous for the larvae when they hatched out, but I guess it is a handy 'hard' surface for the slug to attach its eggs to.
I notice in your photo alongside that there is a small? animal in the Pachycerianthus tube. I presume Dendronotus can get stung by their food, so venturing into the 'lion's den' like this would seem a fairly risky activity.
Thanks for alerting me to Stephanie's photo. I have been in touch with her and am posting her photo separately [message #16634 ]
Best wishes,
Bill Rudman
Nudibranch? from southern California
April 27, 2006
From: Lauri Hamilton
Daisy (my cocker spaniel) spotted this Nudibranch on our morning walk in Los Angeles Harbor. Are they indigenous to sthn California or are they hitchhikers from the tankers?
Locality: Los Angeles Harbor, 3 feet, CA, Pacific, 19 April 2006, Inner Harbor rocks at low tide. Length: 6". Photographer: Lauri Hamilton.
P.S. Daisy also spotted a rock fish, not an small feat. She loves fish.
Lauri
lauri.hamilton@ebfin..com
Hamilton, L., 2006 (Apr 27) Nudibranch? from southern California. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16405
Hi Lauri,
Great comparison to cute Daisy. Floating docks are one of my favorite collecting spots. Great Branch habitat and you can stay dry and warm. I also find that by hanging my underwater camera upside down I can get some fairly good shots. Seems like you have this mastered from the surface all ready, however. Good show.
Your critter is one of the largest dendronotids on this coast, Dendronotus iris. This species, varies in color as you can see from earlier postings, but the key identifying character is the white stripe along the edge of the foot.
Your critter at 6 inches is pretty standard. This species feeds on tube anemones. Kind of hard to imagine them on a dock however. Maybe on the bottom below.
Best wishes,
Dave Behrens
Dendronotus nanus rediscovered in California
August 11, 2005
From: Mark Chapman
I was hoping to see if I could get an ID of this nudibranch, A friend recommended this site to me. He believes it is Behrens #140 top of p. 75 Dendronotus albopunctatus? I am including what I believe is the eggsack. Thanking you in advance.
Locality: La Jolla, San Diego, California, Depth: 46 feet. Length: 3 inches. 31 July 2001. Intertidal sand flats. Photographer: Mark Chapman
Mark Chapman
MCinLB@aol.com
Dear Mark,
When I first saw your photo it reminded me of a dark form of Triopha maculatus but on a closer examination it turns out to be much more interesting. Unless I am very mistaken, it is indeed a species of Dendronotus, but it seems to me to be Dendronotus nanus, a species described from Sonora, Mexico, in 1967 but for which I can't find any other information. The original description by Marcus & Marcus (1967) was based on photographs and preserved animals, so I had assumed that the short branchial papillae in their description were a description of the contracted preserved specimens, but from your photo the papillae do seem to be very short, and arranged in an arch, as in the Marcus's drawings. It almost looks as though the common trunk or stalk found in most species of Dendronotus is absent in this species.
Gordon Robilliard ( 1972) compares this species with D. iris and suggests they should be considered distinct, but felt that the question should be re-examined if the geographical distributions were shown to overlap. Your find does suggest their distributions do overlap, but from your photo, the nature of the branchial papillae look rather different. However I will leave any serious comparison to local experts, familiar with variation in D. iris. The egg ribbon could well belong to this species, but as I have said before, identifying egg ribbons is very risky unless you can catch the animal in the act of laying.
Could you check the locality data please? "Depth: 46 feet. Intertidal sand flats". doesn't sound right unless there is an enormous tidal range.
- Marcus, Er. & Marcus, Ev (1967) American opisthobranch mollusks. Part 2, Opisthobranchs from the Gulf of California. Studies Tropical Oceanography, Miami: 6(1-2), 141-256. (Figs 1-95)
- Robilliard, G. A. (1972) A new species of Dendronotus from the northeastern Pacific with notes on Dendronotus nanus and Dendronotus robustus (Mollusca: Opisthobranchia). Canadian Journal of Zoology, 50(4): 421-432.
This is a very interesting find.
Best wishes,
Bill Rudman
Dendronotus nanus is variant of D. iris [1]
August 11, 2005
From: Ron Velarde
Hi Bill/ Mark,
When I first looked at the photo [message #14507], I immediately thought of Dendronotus iris. Not being familiar with Dendronotus nanus, I looked at the original description in Marcus and Marcus, 1967. And as you state and from the original description, the two species are similar and need further study. However, the two D. nanus specimens (preserved) were only 13 and 10 mm in length. The specimen shown in the photo is 3 inches long! Based on the size and where the specimen occurred, I think that this is just a spectacular color form of D. iris.
If you have the first edition of Pacific Coast Nudibranchs, Behrens, 1980, this "light phase" is shown as #88 on pages 74-75. It is also shown as #68 on pages 56-57 in McDonald and Nybakken, 1980, Guide to the Nudibranchs of California.
Ron Velarde
rvelarde@sandiego.gov
Velarde, R., 2005 (Aug 11) Dendronotus nanus is variant of D. iris [1]. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14541Thanks Ron,
I was pretty sure this animal wouldn't have escaped the notice of the Californian 'branching' community, but I couldn't find a published photo of a similar looking animal or any later reference to D. nanus.
Best wishes,
Bill Rudman
Dendronotus nanus is variant of D. iris [2]
August 11, 2005
From: Dave Behrens
Bill:
Concerning message #14507: Dendronotus nanus is defiinitely a junior synonym of Dendronotus iris (Cooper, 1863). Right now this distinctive color variation, is all over the San Diego area. Incidentally I had lunch with Gordy Robilliard last we. He say "Hi" for all his old Branching cronies.
Dave Behrens
dwbehrens@comcast.net
Behrens, D., 2005 (Aug 11) Dendronotus nanus is variant of D. iris [2]. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14542Dear Dave,
Thanks to you and Ron for a quick response
Best wishes,
Bill Rudman
Giant nudibranch attack from British Columbia
June 29, 2005
From: Marli Wakeling
Hi Bill,
Thought this series of photos goes to show that nudibranchs don't see very well! This time of year there are dozens of these [Dendronotus iris ], but only in the white form. This is an unusual colour form: any ideas why there are some individuals with such a different colour?
Locality: Bowyer Island North, Howe Sound, British Columbia, Canada,
Pacific coast. Depth: 45 feet. Length: 30 cm. 12 June 2005. shell and sand bottom. Photographer: Marli Wakeling
Cheers,
Marli
scubamarli@gmail.com
Wakeling, M., 2005 (Jun 29) Giant nudibranch attack from British Columbia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14068
Thanks Marli,
It does look rather comical. For those of you unfamiliar with these animals, Dendronotus iris feeds on this tube forming sea anemone, Pachycerianthus fimbriatus, which is able to witdraw rapidly into its tube when attacked. The white 'nose' on the nudibranch is ist everted buccal bulb, which contains the buccal mass and radular teeth which it uses - when successful - to grasp and bight the sea anemone. As you say, this is a good illustration of how little they can see.
Concerning colour variation. I know nothing about colour in these species.. Perhaps they retain pigments from their food, but that would mean the Pachycerianthus was variable in colour, or perhaps its genetic varaibility.
Best wishes,
Bill Rudman
Dendronotus iris in Monterey, CA
February 9, 2003
From: Sami Laine
We see a lot of Dendronotus iris on the sandy seafloor in Monterey at night, you can actually see the rhinophores on this one. Image taken off Monterey Breakwater [California, USA] in 12m depth on 5 February 2003.
Sami Laine
sami@kelpdiver.com
Dear Sami,
Thanks for this photo. It is a spectacular animal. I have included a close-up of the head alongside, to show the tiny rhinophore, hidden in the branches of the massive rhinophore stalk.
Best wishes,
Bill Rudman
Re: Swimming Nudibranchs
November 4, 2002
From: Marli Wakeling
Hi Bill,
Peter & Kristen's animal is Dendronotus iris. They are usually found 'swimming' when thrown into the water by a diver, but I have seen some swimming when there are current conditions. There seem to be lots of them around at the moment.
Regards,
Marli Wakeling
scubamarli@excite.com
Wakeling, M., 2002 (Nov 4) Re: Swimming Nudibranchs. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/8350Thanks Marli,
If you have any photos showing colour variation, they would be welcome,
Cheers,
Bill Rudman
Swimming nudibranchs
November 2, 2002
From: Peter & Kristen
Bill:
This year in Western Washington [USA] on Puget Sound, we were canoeing up Hammersley Inlet near Shelton, WA with the incoming tide, when we came upon a "White Lined Dirona Nudibranch" Dirona albolineata spinning slowly up from the gravel bottom. It was all white and about seven inches long [approx 17cm], looking like a giant hairy sea slug or white rabbit of the deep.
It had apparently become dislodged due to the strong tidal current and came involuntarily flying up from the bottom to the surface. It was clearly alive and writhing its nudibranches in an attempt to get some purchase. This animal was longer and much more complex and opaque than the other photos in the Forum, though you can still see the white lines on the mantle and the branches. I had never seen one, and it was mesmerizing to watch it slowly tumble the eddy before it sank quietly back to its home on the bottom.
Great Flying Nudibranchs!
Peter
p.edler@attbi.com
Dear Peter,
Although this has similarities to Dirona it is a species of Dendronotus, most species of which can put on spectacular swimming displays. I can't see all the details but I suspect this is a colour form of Dendronotus iris. One of its distinguishing features is a white line along the edge of the foot. I think parts of this are visible in your lower right photo. If I am wrong I am sure someone will kindly let us know
Best wishes,
Bill Rudman
Dendronotus iris - feeding movies
September 6, 2001
From: Clinton Bauder
Hi Bill,
A local photo/video contest last month induced 2 of us to shoot video of Dendronotus iris attacking Pachycerianthus fimbriatus. These shots are on the web and I figured this group would like to see them. Both were shot in Monterey in less than 10M of water near the Coast Guard Breakwater.
http://www.theshootout.org/2001/Video03.html
http://www.metridium.com/movies/iris.html
The first one was the third place video entry. The second was one I shot and should have entered into the contest instead of the lame jellyfish shot that I did enter (oh well...). Mine features an especially clumsy slug who misses the anemone with the strike. Several local branchers have found this to be amusing.
Clinton
gecko1@apple.com
Bauder, C., 2001 (Sep 6) Dendronotus iris - feeding movies. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5101Thanks Clinton,
Your video is very funny although I must say I even felt a bit sorry for your Dendronotus. Here it is, about to get its 15 minutes of fame and everything goes wrong. We have a tv show here called 'Funniest Home Videos' where people send in video clips of family members and pets having accidents and other forms of public embarrassment. I'd say your video of Dendronotus missing would be sure to win a prize.
Best wishes,
Bill Rudman
Dendronotus iris from Monterey, California
June 6, 2001
From: Clinton Bauder
Hi Bill,
This may fall in to the "happy accident" category. The anchor for the dive boat I was diving off of on saturday dragged a bit before I got into the water. Instead of diving Hopkin's Deep Reef I ended up in Hopkin's Even Deeper Sandy Bottom or something like that. Anyway the bottom at about 28 meters was covered with egg masses from the squid Loligo opalescens. Many of what appeared to be older egg masses were covered by small (< 25mm) examples of Dendronotus iris. It wasn't clear if they were eating the eggs or not.
Larger examples of Dendronotus iris eat the tube anemone Pachycerianthus fimbriatus but I've never seen these smaller guys feeding on anemones. Has anybody else ever observed something similar or have more information on the diet of juvenile Dendronotus iris?
I'd post a picture but my camera is in the shop for some preventative maintenance and thus I didn't have it with me.
Clinton
gecko1@apple.com
Bauder, C., 2001 (Jun 6) Dendronotus iris from Monterey, California. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4510Dear Clinton,
Thanks for the interesting observation. Some species of Dendronotus include hydroids in their diet so perhaps D. iris does as well. It would be interesting if they also ate squid eggs. Hopefully someone will have some observations for us.
Best wishes,
Bill Rudman
Dendronotus iris question
December 19, 2000
From: Ray Izumi
I've been filming Dendronotus iris in British Columbia for several years now. Recently I came across a herd of them (is there a word for a gathering of nudibranchs?) actively feeding, something I had never witnessed even after hours of observation.
I noticed that the nudibranch seems to locate its prey (the burrowing anemone Pachycerianthus fimbriatus) by touch. Watching macro video of the "strike", I could see clearly that the oral tentacles seem to react strongly to the touch of the anemone's stinging tentacles by quickly withdrawing.
Conventional wisdom has it that Dendronotus iris ingests these stinging tentacles and passes them intact through its digestive system and then to its own cerata, where they act as a defense for the animal. Is it possible for this to occur and yet the nudibranch does not develop an immunity to the sting of the anemone? If so, what are the implications of this in regards to mating behavior, where two animals must come in close contact?
Attached is a specimen caught in flagrante delicto at Chup Point in Barkley Sound, British Columbia, in 40 feet of water on sandy bottom littered with Pachycerianthus fimbriatus, temperature 46F, 27 Nov. 2000.
Ray Izumi
izumirm@sprynet.com
Dear Ray,
Thanks for the photo and observations on Dendronotus iris. To answer your questions in sequence, I guess 'herd' is as good a collective noun as I have heard. it would fit many of them, especially Sea Hares, and I quite often use the term myself, though not officially.
On your question about them being stung by the anemones, nudibranchs that feed on stinging food are often stung and you can watch them often trying to avoid being stung. On the problem of nudibranchs with nematocysts in their cerata stinging each other, the answer is that the nematocysts are not released solely through physical contact. The nudibranch has to be alarmed before the cnidosacs release their stolen weapons. Presumably two nudibranchs of the same species in close contact would not be alarmed.
Now to the question about Dendronotus having nematocysts. There has been some confusion in the literature concerning the presence of branches of the gut in the 'gills' or 'cerata' of species of Dendronotus. Firstly there is no evidence to suggest that any species of Dendronotus has cnidosacs at the tip of its dorsal processes in which to store nematocysts. In fact there is no evidence that they store nematocysts from their prey anemones in any part of their body.
The second point concerns branches of the gut. In Dendronotus frondosus some authors reported that it had branches of the digestive gland in its dorsal processes and others said it didn't. What we now know is that there are branches of the gut in the dorsal processes of juveniles but not in adults. In Dendronotus iris there are branches of the gut in the rhinophore stalks and the first pair of dorsal processes but not in any of the other dorsal processes.
Why am I calling them 'dorsal processes'? Well they are clearly not cerata as found in aeolids. Perhaps 'gills' is a better name for them, but I know of no study to show they are important in respiration.
Hope that answers your questions.
Best wishes,
Bill Rudman.
