Ink glands
PHOTO
UPPER: Aplysia californica 'inking'. Coal Oil Point, Santa Barbara, California. Photo: Genevieve Anderson
LOWER: Aplysia dactylomela, releasing ink from its mantle cavity after being disturbed in a rock pool. (Long Reef, Sydney, New South Wales, 21 December 1995). Photo: Bill Rudman.
Genny Anderson's spectacular photo here of Aplysia californica producing clouds of reddish purple 'ink' illustrates one of the most common features of most Sea Hares. The commonly believed function of this ink is that, like the octopus, it provides a screen or decoy so that the Sea Hare can quickly escape when attacked. Howevere, anyone with even a fleeting knowledge of live Sea Hares will realise the a 'fast escape' is not in the repertoire of these slow crawling slugs. In fact we have no idea what the purpose of this purple ink is. I lean towards the idea that it is an excretory product associated with eating red algae, and there is evidence to support that (Chapman & Fox, 1969). Sea Hares have two main secretory glands in their mantle cavity, one we call the Purple Gland lies on the roof of the cavity, above the gill. It usually produces a purple secretion but can also produce a white ink in some species. This is not to be mistaken for the white milky secretions of the Opaline Gland which lies beneath the gill on the floor of the mantle cavity. See diagram showing position of glands in Stylocheilus striatus.
There is a lot of evidence, however, to show that Sea Hares store noxious chemicals from their algal food, particularly from red algae, in their skins, and when these chemicals are secreted, they provide a powerful defence against predation. You will see from messages below that the skin secretions are very distasteful. One extreme example is found in a Western Australian species, Aplysia gigantea which has been implicated in the deaths of many dogs. A comprehensive review by Johnson & Willows (1999) has recently been published. Also see the links below for further information on the topic.
• Johnson, P.M & Willows, A.O.D, (1999) Defense in Sea Hares (Gastropoda, Opisthobranchia, Anaspidea): multiple layers of protection from egg to adult. Marine & Freshwater Behaviour & Physiology, 32: 147-180.
See also:
•Sea Hares - chemical defence References
•Sea Hares - collecting sites in Australasia
•Sea Hares - mating chains
•Sea Hares - Species List
•Sea Hares - what are they?
•Defense in Sea Hares - a review
Rudman, W.B., 2003 (March 3) Ink glands. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/seahatac
Related messages
Is Sea Hare ink poisonous to fish?
January 15, 2007
From: Nicole Chilson
Today our Sea Hare was pulling in like it was trying to form a ball or shrivelling up or something. I wasn't sure if it was doing alright, but didn't feel like getting wet so I touched him with the net a couple of times to make sure he was alive, but then it spit out the ink cloud. Terrifying. I freaked out and netted him and put him in a separate container and changed 4 gallons of water. He/she didn't ink anymore and was moving around fine in the other container so we put him back into the tank. The other fish don't look like the ink effected them. Are they being bothered at all, or is the ink poisonous to them?
Nicole Chilson
Rochester, Mn, USA
nicole.wagner@students.msbcollege.edu
Chilson, N.M., 2007 (Jan 15) Is Sea Hare ink poisonous to fish?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19217Dear Nicole,
Have a look at the Fact Sheet on Sea Hare ink. I think your fish have answered the question themselves. As far as I know it is not poisonous. In aquaria, Sea hares need to eat red algae to make their ink. Normally aquarium Sea Hares are fed green algae so inking is usually not a problem.
Best wishes,
Bill Rudman
How to make dye from the Sea Hare ink.
August 3, 2006
From: Ralph Bowen
I live in Dakar, Senegal and during this time of year there are huge numbers of sea hares on the beach, alive and inking quite freely. Is there a method of using the dye for cloth? Is it boiled?
Locality: Dakar , 5 meters, Senegal, Atlantic Ocean, 01 August 2006, Beach front. Length: 5 inches
Ralph Bowen
bb_lephare@sentoo.sn
Bowen, R., 2006 (Aug 3) How to make dye from the Sea Hare ink.. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/17304Dear Ralph,
It would be interesting to see some photo of your local sea hares. Concerning sea hare ink. A far as I know the pigment in sea hare ink is not suitable as a dye. The ingredient of the pigment is mainly phycoerythrin, and is derived from red sea weeds that the slug eats.
Best wishes,
Bill Rudman
Dolabrifera dolabrifera - Dissection diagram for ink gland?
June 17, 2006
From: Kathryn Clark
Dear Bill,
I am a masters student studying the marine chemical ecology of Dolabrifera dolabrifera and cyanobacteria. I was wondering if you had a detailed diagram of where I could find its mucus/ink gland. I have observed the animals produce a white ink when disturbed and I would like to separate out the gland for chemical analysis. In past dissections, I have separated the animals by skin/parapodia/head, digestive gland and other body organs.
Locality: Coiba Island, Panama, Pacific, 29 May 2006, Intertidal, rocky. Length: 40 - 60 mm
Also if you know of anyone who studies the chemistry of Dolabrifera dolabrifera could you let me know. I have only found one paper on its chemistry
-
Ciavatta M.L et al. (1996) Dolabriferol: A New Polypropionate from the skin of the Anaspidean Mollusc Dolabrifera dolabrifera. Tetrahedron, Vol. 52, No. 39, pp. 12831 - 12838.
Thanks,
Kathryn Clark
ymcsquirrel@hotmail.com
Clark, K., 2006 (Jun 17) Dolabrifera dolabrifera - Dissection diagram for ink gland?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16888Dear Kathryn,
If you go to the General Topics List you will find a whole section on Sea Hares which includes pages on Ink Glands, references, the mantle cavity, and a link to a drawing of the mantle cavity of Stylocheilus showing the position of the opaline and purple glands.
Unfortunately the mantle cavity is a bit more squashed up in Dolabrifera but the basic 'geography' is the same. Unfortunately, dissecting 'fresh' molluscs is difficult because mucus is secreted from almost everywhere. There are references to work on the gland secretions of other aplysiids which should be applicable to Dolabrifera.
Good Luck,
Bill Rudman
Aplysia californica - ink
March 23, 2006
From: Malvina Papanastasiou
Has anybody analysed chemically the ink of Aplysia californica?
Malvina Papanastasiou
malpap@gmail.com
Papanastasiou, M., 2006 (Mar 23) Aplysia californica - ink. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16144Dear Malvina,
Have a look at the Ink Glands Fact Sheet and the page of references on Chemical Defence in Aplysia.
Best wishes,
Bill Rudman
Separating Ink Components of Aplysia dactylometa?
March 6, 2006
From: Scott Schwartz
Hi,
I'm doing an undergraduate study on Aplysia dactylomela and I was hoping to separately test the effects of the different ink components (like opaline) on predators. Is there an easy way to separate the ink, such as putting it in a centrifuge?
Locality: Discovery Bay Marine Lab, Jamaica, Carribean
Thanks,
-Scott
lordvoldemort@hotmail.com
Schwartz, S.W., 2006 (Mar 6) Separating Ink Components of Aplysia dactylometa?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16012Dear Scott,
It's a bit outside my area of expertise. I guess you have looked at the page of references on secretions in Aplysia, some of which apply to work on A. dactyomela. Also have a look at the messages on this page. One difficulty in all work on opisthobranchs is avoiding your sample being contaminated with the normal mucus secretions which these animals produce almost continuously. I don't know how much time you have, but it seems Aplysia can be effectively 'de-inked' [of the purple/red ink] by removing red algae from the diet. It's possible that you could at least sort out the opaline secretion if you fed some solely on green algae. The other thing is that the opaline gland opens on the floor of the mantle cavity while the purple gland opens on the 'roof' [see mantle cavity Fact Sheet; and my reply to an earlier message #7872]. Perhaps you will find someway to physically separate the secretions.
Perhaps someone else will have some ideas,
Good Luck,
Bill Rudman
Re: Inking in Aplysia
October 24, 2005
From: lorrie creach
my 8 year old daughter was on a field trip at a beach in fort myers florida when a classmate looked down and saw a seahare attatched to my daughters leg.she could not shake it off so she grabbed it and pulled it off.in the process,she got inked!! there is a purple stain on her leg and i can't get it out of her sock.
Locality: Bunche Beach, Fort Myers, Florida, USA, Gulf of Mexico. Depth: 1 1/2 foot of water. Length: 4 inches. 19 october 2005. intertidal.
my question is: will the ink go into her pores and harm her in anyway?how do i get the ink off her leg?does it just wear off??
thank you for your help.
Lorrie
xcharmed4evax@aol.com
Creach, L.A.., 2005 (Oct 24) Re: Inking in Aplysia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15092Dear Lorrie,
As you will have discovered by now the ink will not harm your daughter. I am surprised it actually stained her skin and socks. Have a look at the Fact Sheet on Sea Hare ink. The Sea Hare was probably Aplysia brasiliana.
Best wishes,
Bill Rudman
Pharmacokinetic peptides in Dolabella auricularia
July 29, 2004
From: Sallie Dugan
Dear Sir:
I found your website of extreme interest and wonder if you could tell me if it's true that there is some usage of the peptide in Dolabella auricularia. If it is true, how did it come to be used for this purpose and what led scientists to think that it might have pharmacokinetic usages?
Thank you in advance for your insights.
Best regards,
Sallie E. Dugan
Lon Morris College
Jacksonvillve, TX 75766
SDugan@LonMorris.edu
Dugan, S., 2004 (Jul 29) Pharmacokinetic peptides in Dolabella auricularia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12706Dear Sallie,
Have a look at the following messages [#3859, #7430] on the Forum for some background information.
Concerning why Doalbella was targeted. There are a large numbers of chemists worldwide 'bio-prospecting' for potentially valuable [for the drug industry] molecules. Sea Slugs are a good source of such molecules because they tend to concentrate bioactive chemicals for their own defence. But so are softcorals, sponges etc and any animals with venom production such as snakes, spiders cone shells etc etc.
Best wishes
Bill Rudman
Sea Hare color purple
October 24, 2003
From: Patricia
Could you please let me know if the purple colour released by the sea hare was also used by the Phoenicians for dying purposes?
Many thanks
Patricia
pbeller@sdnhm.org
Beller, P., 2003 (Oct 24) Sea Hare color purple. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11298Dear Patricia
Tyrian Purple was a 'red' rather than purple dye, first made in Tyre in the eastern Mediterranean 2-3000 years ago in what was probably one of the earliest chemical industries. The dye was obtained from the hypobranchial gland of muricid snails (Murex, Thais spp). The purple ink produced by Sea Hares, which is also reddish, is quite different and not permanent.
You should find references to the dye in good reference books. On a quick search on the web I found a site Dyes in History & Archaeology which has some basic information on Tyrian Purple.
Best wishes,
Bill Rudman.
Allergic to Sea Hare Ink?
August 13, 2003
From: Martin Masters
We found a sea hare in California on Santa Cruz Island. While showing it to my sons, it released a cloud of purple ink. Since then, I have broken out in a rash resembling poison ivy or poison oak. Is it possible that I am reacting to the ink?
Martin Masters
mastersmw@yahoo.com
Masters, M., 2003 (Aug 13) Allergic to Sea Hare Ink?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/10727Dear Martin,
It's most unlikely the you are allergic to the ink, but anything's possible. It certainly not a phenomenon that has been reported before. It's possible that some microscopic organism, or even a broken up jelly fish, was in the water and affected you. The bristles of some marine worms, and some sponges, can cause rashes, so the list of possible culprits is quite long. You would be best to check with experts in California, as they would know what local organisms are most likely to blame
Best wishes
Bill Rudman
Do frightened Aplysia secrete ink involuntarily?
September 24, 2002
From: Dr. Stephen Hoskins
Dear Bill,
I've been pondering the role(s)of ink and opaline secretions in Aplysia and wondered whether individuals released these chemicals, not as an active form of defence, because there is little evidence to support this idea, but as an involuntary nervous reaction to perceived danger. I'm tempted to use the term "fear" though I appreciate this implies rationalising sensory input which their simple brains may be incapable of.
What are your views on this?
Stephen.
SRH@4TheNet.co.uk
Hoskins, S., 2002 (Sep 24) Do frightened Aplysia secrete ink involuntarily?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/8004Dear Stephen,
Whole university departments have studied aspects of the brain and behaviour of the simple Sea Hare. And the foundation work for Eric Kandel's Nobel Prize was about such things. In all this work I don't think there is any evidence that they can perceive a 'threatening atmosphere' or in 1970s terminology - 'bad vibrations'. Elsewhere I have suggested that 'inking' may be a form of glandular incontinence, but whatever it is, it seems to be the result of some physical assault on their well-being - being stood on, being bitten, being dunked in formalin etc.
Best wishes,
Bill Rudman
Re: Inking in Aplysia
June 27, 2002
From: Edwin Cruz-Rivera
Dear Bill,
Concerning the Aplysia inking message.
P.M. Johnson and I did a number of field experiments with Stylocheilus striatus and Aplysia parvula and found no differences in the susceptibility of sea hares with or without ink. Manually "de-inked" sea hares (no hooks, Bill) were either consumed (Stylocheilus) or rejected (Aplysia) with equal frequency as conspecifics with a full complement of ink. Still, we think ink has a defensive purpose, just not in the conventional way that one usually thinks. It might serve to distract the predator rather than simply repell it. P.M. presented our results recently in the meeting of the AChemS but I don't want to spill the beans too much here. The work will be submitted to publication soon.
As for anemones and lobsters as sea hare predators, I have seen P.M.'s videos of Metridium gobbling Aplysia and I have no doubt in my mind that they can do it in the field. The fact is one hardly observes predation in the field for most organisms. This does not mean it does not occur. Out of hundreds of day and night dives, I have only seen one episode of predation on sea hares: a portunid crab (Thalamita sp.) feeding on a Dolabella. However, if I bring crabs and sea hares to the lab, these crabs will eat sea hares even in the presence of alternative foods. If one considers how voracious, generalized and abundant some of these larger crustaceans are, it is not hard to envision crabs and lobsters as sea hare nemeses.
Edwin Cruz-Rivera
ecruzriv@uog.edu
Cruz-Rivera, E., 2002 (Jun 27) Re: Inking in Aplysia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7373Dear Edwin,
Thanks for the input. I look forward to reading of your research results when they are published. I couldn't agree more with your comments about the difficulty of getting information on predation. It's why I started up the Predation Records page on the Forum. While I do not dispute that in certain places, large sea anemones and large crustaceans may eat sea hares, in many parts of the world there are not large sea anemones in areas sea hares are common, and from my experience - not backed by any rigorous sampling - large sea hare populations can be found in places where large crabs abound.
The other point that needs to be considered when considering the function of the purple gland is its phylogenetic history. The purple gland is an 'ancient' organ which Sea Hares have inherited from primitive shelled ancestors. They are represented today by the family Akeridae. Although its present function may have changed, the purple gland evolved in shelled ancestors. It is not therefore a special organ which has evolved to meet the defensive requirements of an effectively shell-less slug. It may be useful then to look at this gland in Akera to get some clues to its function. Certainly the gland does not protect Akera from being eaten by a variety of bottom-feeding fish. An interesting observation was made by Thompson & Seward (1989) when studying populations of Akera bullata in England. They noted that normal populations produced purple ink but populations of a dwarf form [A. bullata nana] did not. It would be interesting to know if this form lacked a purple gland or perhaps fed on algae without the chemical constituents required to produce purple secretions.
This is a fascinating topic. If you would like to keep us up to date on developments, it would be much appreciated.
• Thompson, T.E. & Seaward, D.R. (1989) Ecology and taxonomic status of the aplysiomorph Akera bullata in the British Isles. Journal of Molluscan Studies, 55: 489-496.
Best wishes,
Bill Rudman
Re: Inking in Aplysia
June 26, 2002
From: Dr.Stephen R Hoskins
Dear Bill,
Concerning my message about inking in Aplysia, here is a reference I have just found.
• Nolen, T.G. & Johnson, P.M. (2001) Defensive inking in Aplysia spp: Multiple episodes of ink secretion and the adaptive use of a limited chemical resource The Journal of Experimental Biology, 204: 1257–1268
Stephen.
SRH@4TheNet.co.uk
Hoskins, S.R., 2002 (Jun 26) Re: Inking in Aplysia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7369Thanks Stephen,
I had a look at this paper. It recounts some pretty horrifying lab experiments where the Sea Hares are suspended on hooks and 'stimulated' in various ways to show that inking is not necessarily an all or nothing event - that is the ink gland is not always completely emptied each time. This they suggest means the Sea Hare is not completely defenseless if 'attacked' before it can replenish its ink supplies. The authors refer to earlier work they have done suggesting that the ink is a defence against lobster and large sea anemone attack. I will have to check these references out, but what puzzles me is whether lobsters and sea anemones can be considered important predators or even potential important predators of sea hares. I am still to be convinced that inking is a real defence behaviour in Sea Hares and not just a form of incontinence brought about by extreme stress.
Cheers,
Bill Rudman
Re: Effect of secretions on Aplysia
June 26, 2002
From: Cathryn Clarke
Hi Bill,
Concerning Stephen Hoskins' message, I came across a study that examined the effect of A. dactylomela ink on itself as well as other animals. Hope it helps.
Carefoot, T.H., S.C. Pennings, and J.P. Danko. 1999. A test of novel functions for the ink of sea hares. Journal of Marine Biology and Ecology, 234: 185-197.
Best wishes,
Cathryn Clarke
Cathryn.Clarke@jcu.edu.au
Clarke, C., 2002 (Jun 26) Re: Effect of secretions on Aplysia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7365Thanks Cathryn,
I'll have to check this out.
Bill Rudman
Effect of secretions on Aplysia
June 22, 2002
From: Stephen Hoskins
Dear Bill,
Has any research been carried out upon the effects of ink, mucous, or opaline secretions on Sea Hares themselves?
Stephen.
SRH@4TheNet.co.uk
Hoskins, S., 2002 (Jun 22) Effect of secretions on Aplysia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7335Dear Stephen,
The short answer is I don't think so. Have a look at the list of references on chemical defence. A number refer directly to these secretions. As far as I can recall none of these secretions have been shown to directly deter other animals [of the same species or not] in 'normal' circumstances. If anyone has information to the contrary it would be very welcome.
Best wishes,
Bill Rudman.
Ink Glands in Octopus and Sea Hares
March 21, 2002
From: Nadine Schoene
Is there any homology between the ink-producing glands of Sea Hares and cephalopods?
Thanks,
Nadine Schoene
inia@zedat.fu-berlin.de
Schoene, N., 2002 (Mar 21) Ink Glands in Octopus and Sea Hares. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6504Dear Nadine,
The short answer is definitely 'no'. If you look at the list of references you will see there has been a lot of research on the purple ink in Sea Hares but we are still not sure whether it has a role in chemical defence. I am not sure if anyone has actually compared the cephalopod ink gland with that of Sea Hares, but they are so distantly related, there is no reason to suspect that the glands have the same origin.
Best wishes,
Bill Rudman
Sea Hares and Inking
March 22, 2001
From: Melanie
Thank you for your reply concerning sea hares and burrowing. Now, I have a question about the use of ink by sea hares. Generally it is believed that sea hares dispel ink as a defensive mechanism. However, I have read several papers that question this proposing it may just be a warning, using a foul tasting mucous that they extrude as their primary defense. One of the papers noted how when sea hares were first approached and grabbed by sea anemones as prey, they did not exude their ink. Only upon more tactile pressure did they ink. If you could provide any information on sea hares and inking I would greatly appreciate it. We are in the middle of setting up an exhibit on inking via various molluscs here at the Mote Marine Lab in Sarastoa, Florida, USA.
Thanks for all your help.
Cheers,
Melanie
pjtmcape@aol.com
Melanie, 2001 (Mar 22) Sea Hares and Inking. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3980Dear Melanie,
If you have a look at the top of this page I have put your message on, you will find some links to more information on the subject. Also have a look at the messages below yours on this page, and on the other pages referred to, as they also contain more information and references. Basically I don't think there is any good evidence that inking is a defensive strategy in Sea Hares. I think the superficial similarity between their ink and that of octopuses led to this idea, but as they can neither hide in it or run away quickly, the similarity with octopuses isn't very sustainable on close examination.
Your question on burrowing turned out to be quite useful as it has led to an interesting observation by Don Barclay that the tropical Sea Hare Dolabella auricularia does indeed burrow.
Best wishes,
Bill Rudman
Sea Hare Self Defense
February 21, 2001
From: Tina Paget
I am doing a report on Sea Hares, in general. One of my topics is self defense. I have found little to no information on this subject. I know about the purple and red secretions it emitts when disturbed, but that's it.
Any ideas?
Tina Paget
luckygal@popstar.com
Paget, T., 2001 (Feb 21) Sea Hare Self Defense. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3847Dear Tina,
If you go to the General Topics List and go down the alphabetical list until you find 'Sea Hares', you will find pages on Attack & Defence, Chemical Defence, and Predators.
Be sure to look throught the messages on each page as most of the information is to be found in the questions and answers and general discussion that you find there. I am not sure if you are familiar with hypertext pages. In case you are not, if you click on any underlined word you will be taken to a page on that subject.
There is a lot of other information on Sea Hares on the Forum which may be useful for your project.
Good Luck with your project,
Bill Rudman
Siphon Withdrawal Reflex in Sea Hares
December 15, 2000
From: Steve Potts
Dear Dr. Rudman,
I am in a chemical ecology course and have chosen to study Aplysia. A paper written by Stopfer, Chen, and Carew: "Evoked Ink Release in Aplysia Produces Inhibition of the Siphon Withdrawal Reflex in Neighboring Conspecifics" suggests that the ink may serve an alarm function. I cannot ascertain from the article, however, what is meant by the "ink rapidly inducing inhibition of the tail-elicited siphon withdrawal reflex" in neighboring Aplysia.
Can you please help me understand what this means?
Thank you very much,
Steve Potts
S_Po@msn.com
Potts, S., 2000 (Dec 15) Siphon Withdrawal Reflex in Sea Hares. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3349Dear Steve,
I am not sure I can help that much if they haven't defined the terms they are using in the paper. When Eric Kandel and others began studying Aplysia behaviour many years ago they needed to qualify, describe and name every part of the Sea Hare's behaviour so that they could describe all the reactions they would observe when studying the effect of stimulating individual nerve cells. The 'siphon withdrawal reflex' is just a name for the withdrawal of the siphon into the mantle cavity when the animal is stimulated some way. I can only assume that a 'tail-elicited siphon withdrawal reflex' is a withdrawal caused by poking the Sea Hare's 'tail' or posterior end of the foot.
It seems they are suggesting that the ink of one Sea Hare makes neighbouring Sea Hares less likely to withdraw their siphons - which doesn't fit with your suggestion that the ink may have some alarm function.
Basically I am not sure. I guess you are aware of Eric Kandel's important books on Sea Hare behaviour. I read recently that he has been awarded a Nobel Prize, so there is still hope for us slug workers.
I would like a full reference to the Stopfer et al paper please.
Best wishes,
Bill Rudman.
Tyrian Purple
August 28, 2000
From: Mary Townsend
I would like to know whether or not tyrian purple was obtained from the Sea Hare, and if not which shellfish was it obtained from.
Mary Townsend
kozianski@fastlink.com.au
Townsend, M., 2000 (Aug 28) Tyrian Purple. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2936Dear Mary,
Tyrian Purple was a 'red' rather than purple dye, first made in Tyre in the eastern Mediterranean 2-3000 years ago in what was probably one of the earliest chemical industries. The dye was obtained from the hypobranchial gland of muricid snails (Murex, Thais spp). The purple ink produced by Sea Hares, which is also reddish, is quite different and not permanent.
You should find references to the dye in good reference books. On a quick search on the web I found a site Dyes in History & Archaeology which has some basic information on Tyrian Purple.
Best wishes,
Bill Rudman.
Turtles eating Sea Hares
May 5, 2000
From: Michael D. Miller
Bill
Following up on your observations regarding large Pleurobranchus forskalii being eaten by turtles in Tanzania, I would like to offer the attached photo courtesy of Dr. Wes Farmer, to add to the predation records. The photo depicts sea turtles dining with gusto on offered sea hares in a holding pen at Bahia de Los Angeles, Baja California, Mexico. It would appear from the photo that the turtles are showing no hesitancy in devouring the hapless sea hare which would seem to indicate prior encounters in the wild.
Cheers;
Mike
mdmiller@cts.com
Miller, M.D., 2000 (May 5) Turtles eating Sea Hares. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2360Thanks Mike,
Bill.
What Preys on Sea Hares?
March 7, 2000
From: Claire
I have been researching sea hares for a web page I am creating. Your site has been extremely the helpful in this process. Thanks. One area I have had a hard time researching is the predators of sea hares. Any insight into this area?
Claire.
Mushbrum@excite.com
Dear Claire,
If you can get hold of a copy of Johnson & Willow's review of Defense in Sea Hares which I noted last year, there is a section on predators. One difficulty is knowing which animals are serious, regular predators, and which have eaten a Sea Hare as a once-off 'experiment' or as the result of a chance meeting. In their paper they suggest sort out a few predators which have Sea Hares as a majot part of their diet. They include a large green sea anemone Anthopleura xanthogrammica, the aglajid navanax inermis, the bailer shell Melo amphora and the giant starfish Coscinasterias calamaria. But you should have a look at the paper for details about which species are eaten etc.
You should also be aware that the eggs are also a useful food item as are metamorphosing larvae about to settle out of the plankton.
Let us know when you complete your website Claire, I would like to have a look.
Best wishes,
Bill Rudman.
Slugs that squirt ink
November 25, 1999
From: Orso Angulo Campillo
Dr. Rudman.
I been working with slugs for 5 years now, and I have seen many times in the tide pools how the Aplysia when it is molested throws ink. But I wonder if Dolabella also can expel some ink as Aplysia does, and it does do you have any reference about it.
Thanks,
Orso Angulo
mol@lapaz.cromwell.com.mx
Campillo, O.A., 1999 (Nov 25) Slugs that squirt ink. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1589Dear Orso Angulo,
Yes Dolabella auricularia produces purple ink. Have a look at the page on that species and the accompanying messages to find some information about its biology. There is also a page of Dolabella references. If you haven't visited the Forum before you will find that on every page there are relevant messages arranged in chronological order beneath the photos and information at the top of the page. Check these messages as there is a lot of relevant information. For example, if you look underneath my answer you will find a number of messages referring to chemical defence.
Also have a look at the page on Sea hares - Attack & Defence for information on Sea Hare ink. There is also a page of references on Sea hares - Chemical Defence.
From your email address I guess you are working in Mexico? If you would like to tell us what you are doing with Sea Slugs I am sure other visitors to the Forum would be very interested.
Best wishes,
Bill Rudman.
A new review of Sea Hare defence mechanisms
August 14, 1999
From: Bill Rudman.
Last year a graduate student, P.M. Johnson, Department of Zoology, University of Washington, Seattle, Washington, U.S.A. pmj@u.washington.edu, sent messages enquiring about Sea Hares, and potential collecting sites.
A pleasant surprise in my mail this week was his thanks for assistance provided by the Forum, and an excellent published review of Sea Hare defence mechanisms. Of particular interest is the distinction the authors make between the milky opaline gland secretion and 'white ink' which is produced by some species in place of the purple 'ink' more commonly associated with aplysiids.
For those interested, the reference is:
Johnson, P.M & Willows, A.O.D, (1999) Defense in Sea Hares (Gastropoda, Opisthobranchia, Anaspidea): multiple layers of protection from egg to adult. Marine & Freshwater Behaviour & Physiology, 32: 147-180.
One predator they miss in the review of egg mass predators, is the aeolid nudibranchs of the genus Favorinus, many species of which seem to feed exclusively on opisthobranch egg masses.
Bill Rudman.
Re: Opaline Gland
June 28, 1999
From: Assaf Zvuloni
Dear Sir
Thank you for responding to my query regarding the Opaline defence system of Aplysia. It is much apreciated .
Sincerely
Assaf Zvuloni
(1st year Marine Biology student)
azvuloni@hotmail.com
Zvuloni, A., 1999 (Jun 28) Re: Opaline Gland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/984Re: Sea Hares - attack and defence
June 23, 1999
From: Assaf Zvuloni
To whom this may concern..
Can someone please explain to us WHAT IS OPALINE?
It's chemical composition etc...in relation to "Sea Hares" .
Thank you for any assistance you can give.
Assaf Zvuloni
azvuloni@hotmail.com
Zvuloni, A., 1999 (Jun 23) Re: Sea Hares - attack and defence. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/968Dear Assaf,
This is an interesting question. Sea Hares can have two special glands opening into the mantle cavity - the PURPLE GLAND and the OPALINE GLAND. Some species of Aplysia including Aplysia depilans and Aplysia juliana do not produce purple ink, they just produce secretions from the Opaline Gland. The Opaline Gland opens on the floor of the mantle cavity, to the right of the genital opening. In some species it opens through a single pore while in others it opens through a cluster of small pores.
Until reading your question I had not noticed that American workers have started calling the secretion from the Opaline Gland opaline. My understanding is that the gland was called the Opaline Gland because of its colour and the milky white colour of its secretion. It is an adjective not a noun. It is not the Opaline Gland because it produces opaline! So the secretion from the Opaline Gland doesn't have a name other than 'Opaline Gland secretion'.
What are the nature and function of the Sea Hare secretions? Although both the Opaline Gland and Purple Gland secretions have been thought to have a defensive function, there seems to be conflicting evidence for that. See following references:
Tobach,E; Zaferes,A; Migenis-Lopez,L (1989): Aplysia ink and opaline: exploration of their relation to predation. Bull. Mar. Sci. 45(3), 664-670.
Nolen, T.G.; Johnson, P.M.; Kicklighter, C.E.; Capo, T. (1995): Ink secretion by the marine snail Aplysia californica enhances its ability to escape from a natural predator. J. Comp. Physiol. A 176, 239-254.
In my reading of the literature there is also no evidence that these secretions have active chemical molecules that could have some function in the Sea Hare's biology. See following reference:
Avila, C. (1995): Natural products of opisthobranch molluscs: a biological review. Oceanography and Marine Biology: an Annual Review 33, 487-559.
So basically I can't answer your question. No active molecules have been isolated from the Opaline Gland secretion, and no defensive function has been shown for it. Perhaps, as some authors have suggested, it is just a way of excreting a waste product.
I would be interested in knowing what your interest in opisthobranchs is? Are you a student or research worker. Are you studying Sea Hares, or are you perhaps a natural products chemist?
Best wishes,
Bill Rudman.
Sea Hares - chemical defence
February 22, 1999
From: Tom Nolen
Bill Rudman:
Here are some more paper citations for your list on the sea hares chemical defense page
(in case you are still updating it):
Coelho, L., Prince, J. and Nolen, T. (1998). Processing of defensive pigment in Aplysia californica: Acquisition, modification and mobilization of the red algal pigment, r-phycoerythrin by the digestive gland. J. Exp. Biol. 201(3): 425-438.
Prince, J., Nolen, T. and Coelho, L. (1998). Defensive ink pigment processing and secretion in Aplysia californica: Concentration and storage of phycoerythrobilin in the ink gland J. Exp. Biol. 201(10): 1595-1613.
Best,
Tom Nolen
Dept of Biology
State University of New York, New Paltz
75 S. Manheim Blvd
New Paltz, NY 12561
(914) 257-3738
TomNolen@mad.scientist.com
OR:
nolent@newpaltz.edu
Nolen, T., 1999 (Feb 22) Sea Hares - chemical defence. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/596Dear Tom,
Everything in the Forum is available for updating! Thanks for these references to your work, which I have added to the list at the top of this page. If you would like to provide a summary of this work I would be glad to add it to the Forum. Perhaps you would also like to add a paragraph to the PARTICIPANTS page.
Best wishes,
Bill Rudman.
palatability of sea hares: personal experience
September 9, 1998
From: Patrick Krug, Ph.D.
Continuing my onslaught through this increasingly entertaining page, I thought I would share the only two examples of predation on an aplysiomorph I've encountered. The first was a large Navanax in the california intertidal. I had read that Navanax was perhaps the only thing that eats small Aplysia, but to my surprise what I found once was a large Navanax with its "teeth" firmly sunk in to an enormous adult Aplysia, maybe 10 inches long, clinging for all it was worth flapping in the breeze! I guess that fell under the category of, "If I can pull THIS off, I'll eat like a king!"
The second instance was me. After reading a paper asserting that Aplysia did NOT contain deterrant levels of chemicals in its skin, I put a small one in my mouth. Has anyone else done this? I promise you, it is the single most HORRENDOUS TASTE you can POSSIBLY imagine. Knowing the chemical structures of the halogenated terpenes singeing one's tongue does not add to the experience. I have made 4 other people do this experiment and everyone agreed it was the most hideous thing they'd ever tasted. I dont know WHAT that Navanax was thinking...
pat
Patrick Krug
19 August 1998
pkrug@biology.ucla.edu
Krug, P. Ph.D., 1998 (Sep 9) palatability of sea hares: personal experience. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/215Re: Sea Hares - attack & defence
May 19, 1998
From: Conxita Avila
Dear Bill,
I just read your page about references on chemical defence in sea hares. I thought may be you would like to add also this reference to the list: Avila, C. 1995. Natural products of opisthobranch molluscs: a biological review. Oceanography and Marine Biology: an Annual Review 33: 487-559. All the references on the chemical ecology of sea hares published before 1994 should be listed there.
Best regards,
Conxita
Conxita Avila
Blanes, Girona,
Spain
conxita@ceab.csic.es
Avila, C., 1998 (May 19) Re: Sea Hares - attack & defence. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/144Thanks Conxita, your comprehensive review missed out by mistake. I have added it to the list today....Bill Rudman
Re: Sea Hares - attack & defence
April 21, 1998
From: P.M. Johnson
Dear Dr. Rudman,
Thank you very much for your quick reply to my questions. Thanks also for the reference list, there was one (Fiorito et. al., 1985) that I was not aware of and that could be very helpful to me. There is another reference that you might want to add to the list:
Nolen, T.G.; Johnson, P.M.; Kicklighter, C.E.; Capo, T. (1995): Ink secretion by the marine snail Aplysia californica enhances its ability to escape from a natural predator. J. Comp. Physiol. A 176, 239-254.
This paper came out of my undergraduate senior thesis at the University of Miami, so I can send you a reprint if you like.
I have several of your papers on opisthobranchs, in most of which you discuss the various mantle glands of different species. It's been suggested by several authors that the ink gland of the Aplysiomorpha was derived from the hypobranchial gland. I was wondering what you're thoughts are on this and also if you know of any possible precursors to the opaline gland as well.
Thanks again for your help,
pm
P.M. Johnson.
pmj@u.washington.edu
Johnson, P.M., 1998 (Apr 21) Re: Sea Hares - attack & defence. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/143It is very hard to find evidence to show whether mantle cavity organs in one group are homologous (that is have the same evolutionary origin) with organs in other less closely related groups. There has been a burst of activity in studying the evolutionary relationship of gastropod molluscs over the last decade and although this work has been a great step forward it also shows us how much we still have to learn. A good reference to this work is W.F.Ponder & D.R.Lindberg, 1997. Towards a phylogeny of gastropod molluscs: an analysis using morphological characters. Zoological Journal of the Linnean Society: 119, 83-265. We can make guesses about the origins of these glands, and there are similar glands in other primitive opisthobranchs such as the aglajiids, but it is just as likely that they evolved independently in each evolutionary line. To me, of greater interest is what is the function of these organs? and why do some species of Aplysia not have a purple gland? ...Bill Rudman.
Rudman, W.B., 1998 (Apr 21). Comment on Re: Sea Hares - attack & defence by P.M. Johnson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/143Sea Hares - attack & defence
April 17, 1998
From: P.M. Johnson
I'm currently writing a review article with my PhD advisor (Dr. Dennis Willows, director of the Friday Harbor Marine Lab) on defence in sea hares. If anyone as observed any sea hares being attacked by a predator under natural conditions I would love to include the details of the account in the review.
Thank you for your help.
P.M. Johnson
Zoology Dept., University of Washington,
Seattle, Washington, U.S.A.
pmj@u.washington.edu
Johnson, P.M., 1998 (Apr 17) Sea Hares - attack & defence. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/142The only example I know of is Richard Willan's unpublished report of a large multi-armed starfish Coscinasterias eating an Aplysia dactylomela in New Zealand. If Kirsten Benkendorff's report of the starfish Patiriella exigua possibly eating the egg mass of Dolabrifera dolabrifera is confirmed, that could possibly count as another example. A common feeder on Aplysia egg strings is the aeolid nudibranch Favorinus japonicus. Have a look at my list of references on chemical defence and related topics.
Bill Rudman.
