Dear Charles,

I have never heard of anything like this. The Emperor was deeply interested in marine biology and sponsored much scientific research, including Baba's publications on the Opisthobranchia of Sagami Bay, so the suggestion that the Emperor was doing marine research is correct. However I know nothing about brain-eating slug research. The other possibility is that 'slug' was used by Daniel Dennett in a broad sense to describe a 'squishy invertebrate'. Philosophers and non-scientists don't always realise that precision in the use of names can avoid a lot of misinformation. There are invertebrate and chordate larvae [ascidians for example] which have a head etc as as a free-swimming larvae but lose it when they metamorphose into an adult. Again it is not very precise to say they 'eat' their brain - what they do is reabsorb the tissue and re-organise it much like a caterpillar does when it metamophoses into a butterfly.

I'm not saying this is what Dennett or the Learning Company lecturer was in fact talking about, but while on the surface the quote you are querying may sound very stange, it may have a sensible explanation.

Best wishes,
Bill Rudman

Dear Erwin,

Have a look at my answers to questions on sea hare eyes #13598 and nudibranch eyes #2377

Best wishes,
Bill Rudman

Dear Emma,
Our nose functions as both a 'breathing tube' and a sensory organ to smell chemicals in the air. Sea slugs don't have a similar organ. They live in water so they use gills for 'breathing'. For 'smelling', most nudibranchs have a pair of rhinophores which is a word made up from Ancient Greek and means 'nose carriers'. Have a look at the Rhinophore Page for some photos and further information.
Best wishes
Bill Rudman

Dear Jacke,
I have no idea. Perhaps someone with time on their hands has studied this, but if so I haven't heard of it
Cheers
Bill Rudman

Dear Rachel,
I guess you are doing a school project. If you go to the GENERAL TOPICS INDEX you will find links to quite a lot of general information on sea slugs.

I can give you very brief answers to your 3 questions but have a look at the general pages for more detailed information.

Concerning their skeleton - slugs, like all molluscs, dont have an internal skeleton and although some books suggest that their shell - if they have one - is an external skeleton (exoskeleton) its main function is defence rather than body support. Molluscs rely to a large extent on the fluids in their body to keep their shape and to exyend their gills and tentacles. Their body contains large blood-filled cavities and by using specially arranged muscles in their body wall they are able to change shape to meet changing needs. We call this sort of 'skeleton' a Hydrostatic Skeleton after 'hydro' which is the Ancient Greek word for water.

What do slugs eat? There are many different sorts of sea slugs, and if you look at some of the earlier message on this topic you will see that they range form bacteria feeders through herbivores, to specialised carnivores. If you look at the Solar powered Sea Slug page you will see that some, with a lttle help from plants, can photosynthesise -so basically they fit at all levels of the food chain.

Yes and some do feed on animals quite similar to 'jellyfish'. Have a look at the page on Glaucus.
Best wishes,
Bill Rudman

Dear Maria,
I get 4 or 5 messages like yours every week, often with pleas to send the information immediately as the assignment is due tomorrow! Basically there are not enough hours in the day for me to do this, and also keep the Forum going and do my real job, etc. This reply is addressed not just to you but to all the other requests I regularly get to do school, university assigments.

If you have an assignment to do, then I guess your teacher expects you to do the research. I guess if you go to a library you might expect the librarian to suggest a few books, but you wouldn't expect them to look up the books for you. There is a lot of information in the Forum. Below the banner at the top of each page there is a navigation bar with a number of buttons. Try the General Topics List, the Search button, or any of the other pages that will get you into the Forum. I am sure you will find enough to complete your 'huge work'.

Although I don't welcome 'please tell me everything about sea slugs' inquiries I do welcome specific enquiries about identifications and aspects of the biology and natural history of these fascinating animals.
Best wishes,
Bill Rudman

Dear Jeanette,
There has been a lot of work done on the nervous system of Sea Hares and some on pleurobranchs, but not too much on nudibranchs. All these animals have specialised areas such as the rhinophores and oral tentacles which can sense chemicals (ie: 'taste' possible food items), but I don't know of any taste organs within the mouth. I guess the difference between 'us' and 'them' is that we test potential food items by looking and smelling and then putting them in our mouths to taste them, whereas opisthobranchs have a reflex feeding action which is triggered after the food has been tested (tasted) externally.

Concerning vibrations. I am sure all animals can sense vibrations. If you tap the side of a tank, nudibranchs will retract their gills and rhinophores, a sure sign they have felt or 'heard' something.
best wishes,
Bill Rudman

Dear Jeanette,
We still have a lot to learn about activity cycles in sea slugs. There is some information scattered throughout the Forum but I haven't as yet prepared a specific page on the topic. The general feeling about tropical nudibranchs is the reverse of your suggestion. During the day it is thought that only phyllidiids are distasteful enough to blatantly expose themselves while other nudibranchs are hiding under rocks, in crevices, or asleep. The very nasty chemicals that phyllidiids have in their skin are considered so distasteful to fish that they are avoided.

Another group of colourful nudibranchs, the chromodorids, also have nasty chemicals in their skin to deter predators. In both tropical and temperate waters, some species of this family are often out during the day, often in groups. These species usually have a colour pattern which is very similar to that of a group of other species. Have a look at the page on Red Spotted species to see why we think groups of species share similar colour patterns.

Many other nudibranchs are so well camouflaged, or so small, that they are usually overlooked by all but the most fanatical or experienced nudibranch hunter. Also many sponge-feeding dorids eat species of sponges which prefer shaded places and crevices so the nudibranch, even if active during the day, is not very visible. In general we can say that some species have developed protective strategies to allow them to out and about during the day, others have not. There doesn't seem to be any simple rule. Have a look at the page on Defence for some more information.
Best wishes,
Bill Rudman

Dear Elianny,
Have a look at my replies to Nisihina Chikako's messages asking about cf and other abbreviations - message 1; message 2.
Best wishes,
Bill Rudman

Dear Patty,
Sea Slugs are found in all seas of the world, not just tropical reefs. To find some photos of sea slugs from interesting places go to the SEARCH page and type in antarctica or arctic and you will get a list of names of sea slugs found in the coldest parts of the earth. Click on any of the names and you will go to a page with photos of the species.

As well as living in all parts of the world they are also found from the intertidal zone to more than a kilometer deep. Like other animals, each species lives in a certain geographical area, and prefers a particular habitat. There are a few exceptions - if you look at the messages on Umbraculum umbraculum you will find a single species that lives from the intertidal to at least 270 meters deep.

Best wishes,
Bill Rudman

Dear Patrick,
I'm afraid your question iisn't quite as simple as it seems. 'Sea Slug' is a general name like 'fish' or 'bird' for a whole lot of different animals belonging to many different families. Have a look at the What is a slug? page and other pages it refers you to. And have a look at the General Topics Page for an index of further topics of interest. And if you go to the Species List you will find many different types of sea slugs arranged in their families. Perhaps you should just choose one group. Why don't you just use the Sea Hares which all belong to the family Aplysiidae.
Good luck with your project,
Bill Rudman

Dear Chikako,
I think the answer to all your questions is yes.

The only universal and unambiguous name for a species is its scientific name. That is why we have so many rules and an International Committee to supervise naming of species and to sort out problems as they arise.

However it is not always practical to formally name or identify every apparent species we find in our day to day work. For example when we get material to identify for ecological studies and surveys the ecologists are usually more interested in how many different kinds of animals are present and are not willing to wait for the few taxonmists available to either identify all the animals present or if necessary give them new names. So we have these conventions Atys sp. 1, Atys cf. naucum, etc. They do not have universal meaning and only apply to the immediate job, report, or book. For example there is a species which Terry Gosliner has called in his South African book Glossodoris sp. 4 which in the Forum I have called Glossodoris sp. 1. As long as future workers note where the 'name' is used there is no confusion. And yes calling something Glossodoris sp. 1 does not necessarily mean that the species does not have a species name, it could just mean that I don't know it.

Concerning 'Common names' and 'Local names'. I could be wrong but I think in Japan you have a formal system of giving animals a Japanese language common name. For example when Hamatani described Cyerce kikutarobabai he also gave it the Japanese name Kanoko-urokoumiushi. I think this is unique to Japan. In other countries 'common names' or 'local language names' have either existed for hundreds of years in very small geographic regions, or have been made up quite recently either in local communities, or have been invented by authors or publishers for popular books. In Sydney local divers call Pteraeolidia ianthina the Blue Dragon because they think it looks like the heraldic dragons on Chinese temples, but I don't know of people anywhere else calling it that. I guess the Spanish Dancer for Hexabranchus is one of the few common names which are really common.

I realise this is probably difficult and complicated to follow in English, so if it still puzzles you please don't hesitate to ask again.
Best wishes,
Bill Rudman

Dear Chikako,
These abbreviations you mention can be confusing but they have a distinct meaning.

sp as in 'Chromodoris sp.' means this is a species belonging to the genus Chromodoris. It does not necessarily mean that the species does not have a name. It just means that the person using 'Tritonia sp.' does not know if the species has a name. In the Forum I have numbered these unnamed species Chromodoris sp. 1, Chromodoris sp. 2 etc so we can refer to them easily.

In some cases I have used names like 'tritoniid sp. 1'. This just means that I am not sure what genus the species belongs to but it does belong in the family Tritoniidae.

spp as in 'Chromodoris spp.' is the plural of 'Chromodoris sp.'. It just means some, or many, species of Chromodoris.

cf is from a Latin word and means 'refer to' or 'compare with'. So when I call something Chromodoris cf. maculosa it means I am not sure what it is but I think it could be Chromodoris maculosa or something closely related, or it looks quite like it. It has no taxonomic status and is just a convenient way of temporarily naming an animal until its true identity can be worked out.

var I don't use 'var' which is short for 'variety'. Some taxonomists used to subdivide species into distinct varieties or forms based on some difference in colour or shape, and they used to give these 'varieties' names. Variety names have no status in zoological nomenclature. I talk of colour variations but that is just to describe colour pattern differences.

I hope that makes sense. If not, please ask me to explain anything you don't follow. I realise it must be difficult for those of you whose first language is not English so don't worry about asking me to explain again. I am happy to do so.

Best wishes,
Bill Rudman

Dear David,
The word nudibranch is made from two Latin words nudus = naked and an branchia = gills. All sea slugs have evolved from snails which have a shell. Nudibranch essentially means 'naked gills' and refers to the fact that in sea slugs the protective shell is lost and the gills are exposed [see photo alongside]. In many nudibranchs, the gills can be quickly withdrawn into a gill pocket if they are in danger of being nibbled by a predator.

For more background information look at the following pages:
•What is a slug?
•How snails became sea slugs
•Torsion and nudibranch gills

Best wishes,
Bill Rudman

Dear Maggie,
How's your dog? Some sea slugs do have nasty tasting chemicals to stop things eating them but I doubt they would actually poison an animal that ate them. Since I don't know what sea slug your dog ate, or where in the world you come from, I can't say much more. But if your dog is like mine - their stomachs can survive the most revolting meals
Best wishes,
Bill Rudman

Dear Heidi,
I'm afraid without a bit more information I can't say whether the animal your son found was a sea slug or not. It is possibly a Sea Hare. Have a look at the Sea Hares Page and perhaps the page on Aplysia californica, which as its name suggests, is one of the Californian species of Sea Hare. Was your find a Sea Hare? If not, I would need some more information before I could hazard a guess.

If you find things washed up on the beach it is worth remembering that normally they live in water, so if you want an idea of their shape it's best to put them in a pool or a bucket of sea water so they have a chance to 'act naturally'. I wouldn't like to give advice on what is and what isn't dangerous to pick up on Californian shores. Seek advice from one of your local natural history museums. In general though, there aren't that many things which it is dangerous to touch. I guess it has to be balance between stimulating your son's natural curiosity and a mother's natural caution. My advice is to seek local knowledge on local dangers. I am sure they will be very few.

On your general question about whether sea slugs are dangerous. The only one I know which can cause a nasty sting is Glaucus atlanticus and its close relative Glaucus marginata. They live with, and feed on Physalia, the 'Portugese man-o-war', which can cause painful stings to swimmers. If you go to the Glaucus page your will see that Glaucus and Glaucilla store the nastiest stings from Physalia in their own bodies. But apart from these two species I think you will be fairly safe with sea slugs.
Best wishes,
Bill Rudman

Dear Sarah,
Why do you need to know their importance to man? I am afraid we humans have the attitude that all the organisms on the earth are here for us to exploit, and if we can't use them they have no real value. We should value all living things because they exist and make up the diverse world in which we live. Without a healthy diverse ecosystem neither humans, nor most other organisms could survive.

I think in your book you should say they are beautiful, they give many divers and visitors to the sea shore delight and excitement. They are part of a great network of plants and animals living together. They have been on earth many millions of years longer than humans, and they and their environment should be protected and treasured. And if you want evidence, 5000 different people are visiting the Forum every month because they are interested in sea slugs. 5000 reasons why we should value sea slugs.

We don't don't need to make up reasons why we should value them. My hope for the future is that today's kids will stop asking questions such as 'what is the value of that animal?' and start asking 'is what I am about to do going to destroy that species or that environment?'.

Basically we don't own nature. Only when we accept we have no God given right to take, use, exploit and ultimately destroy everything that is here on the earth with us, will there be much hope for our future.

Good luck with your book,
Bill Rudman.

Dear Nick,
A good question. I have been planning some general pages but I have too many specific questions to answer so never quite get the time. If you look at the general Topics Index you will find quite a number of general areas covered.

One good website with general information is
bernard Picton's Nudibranchs of the British Isles which has some general background information. Also have a look at some of the other websites listed on the LINKS page.

I hope this is of some help,
Bill Rudman.

Dear Eric,
It's a bit hard to say anything very sensible without a photo, drawing or description. However if these things are green and associated with Caulerpa the chances are that they are not nudibranchs but sacoglossan sea slugs, which are herbivores. Some have shells and some have lost them completely and do look like nudibranchs.

Have a look at the correspondence I have been having with Ron Dahrling on this very topic. Your friend's mystery animal may not be Oxynoe but it is probably a sacoglossan. As I suggested to him have a look at the animals listed under the Order Sacoglossa in the Species List to get an idea of their range of shape and colour.

Best wishes,
Bill Rudman.

Dear Jennifer,
I am afraid asking about a Bubble Shell is like asking about a fish or a bird. It is a name for a whole group of primitive Sea Slugs that still have a shell. Some examples are Bulla ampulla, Haminoea cymbalum, and Hydatina physis. If you click on any of the underlined names you will go to a page about that bubble shell. Also have a look at the messages on each page where you will find more information and photos of their shells.

Bulla and Haminoea are herbivores, feeding on green sea weeds, but Hydatina is a carnivore feeding on worms that burrow in the sand.

Good Luck with your project,
Bill Rudman.

Dear Kathleen,
Have a look at the questions and answers below yours on this page. You will find quite a lot of information there. I am not sure if you realise, but if you click on any underlined words you will go to another page on that subject. If you go to the list of General Topics you will find an index of pages with the type of information you are after - except whether or not you can play games with them.

I sorry I can't provide a same day service, but I suspect your teacher didn't give you an assignment to be answered in one day either.

Best wishes,
Bill Rudman.

Dear Jennifer & Kate,
I don't know if Kathleen is doing the same assignment but have a look at my reply to her question. Basically there is a lot of information to be found on this page and on the pages you will find on the General Topics page. Just click on any underlined word and you will be taken to another page.

Also have a look at other messages on this page and use the SEARCH BUTTON to find other information.

Good luck with the project. If you can't find information on a specific point I am happy to answer a specific question.
Best Wishes,
Bill Rudman.

Dear Jacob,
One of the problems of being a sea slug is that they have no real protection from drying out. Nudibranchs breathe through their feathery gills and also through their skin, and if they dry out, they can't breathe and will die. One reason that land slugs and snails are 'slimy' is because they produce a layer of mucus over their skins to keep them wet.

Like fish and most marine animals, once they get caught outside their normal watery environment they will quickly get into serious trouble. Nudibranchs usually stay near their food, such as sea anemones, sponges etc., which will also die if they dry out. Since their food will only grow in areas that stay wet, nudibranchs are usually safe from being caught out of water.

Good Luck with your project,
Bill Rudman.

Dear ?,

Yes, all sea slugs have eyes but they aren't very good at seeing things. We think that all the eyes can do is let the slug know whether it is light or dark, or when a shadow is passing over them. This might be useful if the shadow is made by a fish or something that is coming to eat them.

The eyes in sea slugs are embedded in the skin not on stalks like land snails. Have a look at the page on the Dorid head for a photo of a nudibranch eye. I have also added a couple of photos here showing the eyes in two other sea slugs.

PHOTO: Costasiella. Arrow pointing to eyes. Photo: Lindsay Warren].

It seems a shame with all their beautiful shapes and colours that they can't see each other.

Best wishes,
Bill Rudman.

PS: Normally I delete anonymous messages, but I assume the lack of a name and address was a mistake.

Dear Ross,
Sounds like you have a project to do. Have a look at the messages below yours on this page for some general ideas on how to use the Forum. Baiscally have a look at the General Topics List and use the Search button. Obviously if you are interested in special adaptations it would be worth your while to look at pages on colour and defence.

Best wishes,
Bill Rudman.

Dear Mark,
You have come to the right spot if you want information on sea slugs. If you look at some of the topics at the top of the page you will see that this site is more than just a message distributor.

Your best move would be to look at some of the messages and answers below yours on this page. You will find directions and ideas on how to use the Forum which will help you to find the sort of information you are looking for
Best wishes,
Bill Rudman.

Dear Emilee,
I guess your teacher wanted you to do this project so that you would learn how to research a topic and find some information for yourself. I wouldn't really be helping you by handing all the information to you on a plate.

What I can do is suggest you press some of the buttons on the blue Navigation Bar at the top of the page and find some information yourself. Probably the best place to go is the General Topics Index where you will find a large list of interesting subjects. Try also the 'What is?' Page which has a lot of questions and answers. Look at the messages and answers on each page as they often have much more information than at the top of the page.
Good Luck with your project,
Bill Rudman.

Dear Samantha,
Have a look at my answer to Sheila Harper's question. Also have a look at Food or feeding in the General Topics Index.

Another way to find things in the Forum is to use the SEARCH button at the top and bottom of each page. If you type in food or feeding you will get a large list of pages.

Hope this helps,
Bill Rudman.

Dear Lillie,
'Breathing' is basically the process animals use to take oxygen into their bodies and remove carbon dioxide and other unwanted gases. Land animals usually have some internal sac (lungs) connected to the body's blood system to do this. Many small animals living in water are able to exchange dissolved gases directly through their skins and so don't have any specially developed breathing organs. Bigger animals, with thicker skins and usually some internal blood circulatory system, often have some structure with thin skin which they use for 'breathing'.

Often they have some sort of feathery 'gill' or set of gills, each gill being a very folded patch of thin skin. Many nudibranchs have gills. Other nudibranchs, especially the aeolids, have tubular organs, called (cerata), which serve the same purpose.

In some nudibranchs, especially in the genus Phylodesmium, these cerata can drop off, much like a lizard drops it tail. These cerata can be regrown, which may have led to the story you have heard that they grow a new one every day. Have a look at the page on autotomy to see examples. You will find good examples of gills on the Torsion & Nudibranch Gills Page.

Best wishes,
Bill Rudman.

Dear Nishina,
I guess the book you are talking of is Atsushi Ono's on Kerama Is. I haven't seen it yet and look forward to receiving a copy. If you have questions, animals you can't identify, observations or photos I am happy for you to send them to the Sea Slug Forum. Anything to do with sea slugs is welcome. In this way we can all help to build up a 'worldwide book' on sea slugs for everyone to consult.

You can either send messages and photos by using the SEND NEW MESSAGE button on the Messages Page or by sending me an email message with photos attached. If you have trouble scanning photos you could post them to me by airmail and I would return them to you after scanning.

Now to your question about how do we decide what is a species? 

The general philosophical question - What is a species? - will be debated whenever two biologists meet! For practical purposes we tend to define 'a species' as being a unique group of interbreeding organisms with a unique set of genetic information. Usually we consider that a species is unable to breed with any other closely related species. However at this point the debate begins!

For practical purposes we tend to define a species as a group of organisms with a unique combination of characters. These characters can include anatomical features, colour patterns, behaviour, food preference, reproductive behaviour, egg masses, larval development etc.

If you look at the messages I have just put on the Forum from Yoshi Hirano, you will see that slight colour differences, differences in penis shape, and differences in the egg mass and larval development all helped to show him that he had two quite distinct species of the aeolid genus Facelina.

Once we have found a combination of characters which make a species distinct we then need to try and find some simple 'indicator' characters so that we can identify the species easily. If the only characters we have to identify a species are internal parts of the anatomy, then its very difficult for a field naturalist to identify the species. After all we can't do ecological studies if we have to kill and dissect every specimen to identify it.

An example would be the red-spotted chromodorids in southeastern Australia. Have a look at my message where I explain why there are so many species there with very similar colour patterns. In southeastern Australia many species have red spots, so it is necessary to look at other features of the colour pattern, such as colour of gills or rhinophores to find useful characters to identify living animals in the field.

There is of course a difference between identifying a named species, and deciding a particular animal is a new species. Deciding which differences are important enough to justify considering an animal a distinct species needs a broad knowledge of related species. It also needs access to a good library so all the past descriptions of related animals can be checked so that we can see if the animal already has a name. For example, when I find an animal in Australia which I am unfamiliar with, I need to look at all the descriptions of similar animals from all parts of the Indian and Pacific Oceans, from east Africa and the Red Sea, to Japan and Hawaii, because it is possible that the species lives throughout this vast region and someone else has found and named it somewhere else.

It is also important to realise there is a lot we don't know about opisthobranchs. There are still many examples of 'species' or 'variations' which we are unable to be sure about at this stage. An example here in the Forum is a red-spotted Chromodoris from eastern Australia which I suspect is a geographic colour form of the widespread Chromodoris fidelis. It is possible that it should be considered a distinct species but at this stage there is no clear way to decide one way or the other.

Another example would be the orange-spotted species of Nembrotha from the Philippines. Until the anatomy of these three animals is studied we cannot say whether we have one, two or three species. We can't even be sure they are all species of Nembrotha.

At this stage I know of no use of DNA comparisons to determine nudibranch species. Comparisons of enzymes by gel electrophoresis has been used a few times but techniques, such as DNA analysis, are too expensive for most of us to contemplate.

I hope this is of some help,
Best wishes,
Bill Rudman.

Dear Hartzell,
If you look through the Forum you will find a lot of information on Sea Slugs. I have put your message on the "What is?' page and if you look below your message there are many other similar questions which I have answere. These answers should give you quite a few interesting facts. For more information go to the General Topics List and choose some of the pages listed there for further topics. You can also Search the Forum for any word which you think is interesting. For example typing food or feeding will give you a list of pages with information on those subjects.

Best wishes,
Bill Rudman.

Dear 'K',
I hope you don't mind me calling you "K" but you forgot to give me your name.
You will find quite a bit of general information on Sea Slugs in the Forum. If you go to the GENERAL TOPICS Page you will find a list of topics which will be of interest. Don't forget to look at the messages at the bottom of each page as they have a lot of extra information in the answers.

To your specific questions:
- which oceans sea slugs are found in?.
They are found in all oceans of the world. Have a look at the Antarctic Page to see wonderful nudibranch sea slugs from Antarctica!

- in what part of the oceans they are found?
Most sea slugs have very specialised diets so they are normally found near their food. So some are found in estuaries, rocky shores, coral reefs, from the intertidal to quite deep water. There is a picture of one sea slug, Umbraculum umbraculum which is found in eastern Australia from the intertidal to 274 meters deep!

- what kind of problems do seaslugs have in their habitat?
I'm not quite sure how to answer this. Most animals have evolved so that they live, as much as they can, in harmony with their specific environment. So they have all the normal problems of life. For example: they need to find food, be safe from predators, and be able to reproduce so there is a next generation. Many sea slugs have evolved defence mechanisms to protect them from predators. Have a look in the GENERAL TOPICS Index that I mentioned above for pages on Defence. You should find some interesting things for your project there.

Best wishes,
Bill Rudman.

Congratulations Christian,

Any chance of some French nudibranch pictures for the Forum?

Bill Rudman.

Dear Christian,

Thanks for your questions. I hope these answers are useful. If you and your diving friends have any photos of the nudibranchs you are seeing I would be happy to post them on the Forum.

Are nudibranchs blind?
Nudibranchs have eyes, embedded deep in the skin. Have a look at the page in the Forum about the dorid head for some information about the eye and its function, and other sense organs.

Basically their eyes can't 'see' in the sense of forming images, and apprently can't do much more than detect shadows and light.

Can nudibranchs self-fertilise?
Nudibranchs, and other Sea Slugs, are hermaphrodite. That is they have a fully functional set of male and female organs. I know of no evidence that shows that they can fertilise their own eggs. As far as I know they have to mate with another partner.

Best wishes,
Bill Rudman.

Dear Carlo,
Thanks for the questions. I have been meaning to put up some pages on parts of the anatomy, so your questions have been an excuse to do these two pages. To answer your questions on the cerata and rhinophores have a look at Rhinophores - in nudibranchs and Ceras, cerata - in aeolids.

To your question on how many species of opisthobranchs are known, I admit defeat. I could only make a guess. If any one has a good reference or any ideas please let us know.

Best wishes,
Bill Rudman.

Dear Steve,
I am glad you are interested in nudibranchs. There are a number of ways to find information about them on the Sea Slug Forum.

Firstly if you look at the top of the page there is a row of navigation buttons starting MESSAGES - SPECIES - PARTICIPANTS - etc
If you click on one of those it will take you to a list of pages which you can look at.
For example on the SPECIES page you will find a list of all the different Sea Slugs we have pictures and messages about on the Forum. All the ones under ORDER NUDIBRANCHIA are nudibranchs, so if you look at some of those you will get an idea of their range of shape and colour. If you go to the GENERAL TOPICS page you will find a list of pages on particular aspects of Sea Slug life-history, etc. Your message is on the "What is a Sea Slug? nudibranch?" page. If you look below your message you will find quite a few earlier messages. If you look at them, and my answers, hopefully you should get information on most of your questions.

If there are particular things you would like to ask about please let me know and I will try and answer them for you.

You can also do a search of the Forum. If you look at the yellow band at the top of your message you will find a button saying "Search the Forum". If you click on it, it will take you to a page where you can type in a word or two and see if there is anything about it in the Forum.

Good luck with your project,
Bill Rudman

Dear Beth,
I have posted your 2 messages together. I don't publish all the nice comments I receive in various ways about the Forum, but yours had that feeling of excitement and pleasure which makes the time we spend on the site really worth the effort. If Dale wants to ask any further questions at any time just send them in.
Best wishes,
Bill Rudman

Dear Dale,
Thanks for your questions.
What is the biggest sea slug?
I think the biggest Sea Slug is a species of Sea Hare called Aplysia vaccaria which is found on the west coast of North America from Morro Bay, California to the Gulf of California. Dave Behrens, in his book "Pacific Coast Nudibranchs" says it can grow to about 1 metre long and can weigh nearly 14kg. The only photo of it I can find on the web is on Mike Miller's Slug Site. He has a photo of the nudibranch Tyrinna evelinae, and because it was named after Eveline Marcus, he has a photo below it on the same page with Eveline Marcus holding an Aplysia vaccaria in her hand. It doesn't seem to be a metre long though.

Have a look at the Sea Hare topics listed in the GENERAL TOPICS index for some background information on Sea Hares.

The biggest nudibranch, which are the most colourful Sea Slugs, is usually said to be Tochuina tetraquetra which is found in the north Pacific, from the Kuril Islands in Russia, south to Malibu, in Los Angeles County, California. A picture of it can also be found on Mike Miller's Slug Site.

What do sea slugs eat?
Sea Slugs eat a wide variety of foods. Some, such as the Sea Hares are herbivores, eating sea weeds. Others such as the nudibranchs are specialised carnivores, each species feeding on a particular food. If you look around the Sea Slug Forum you will find some photos of different Sea Slugs and their food. A few examples of nudibranchs feeding are:
Glaucus atlanticus which feeds on the floating cnidarian Physalia,
Gymnodoris subflava, which feeds on other nudibranchs,
Favorinus japonica, which feeds on other Sea Slug eggs, and
Jorunna sp., which is one of many dorid nudibranchs that feed on particular sponges.

What ocean do sea slug live in ?
Sea Slugs live in all oceans of the world. Each region has its own species, but some species can be found right across the tropical Indian and Pacific Oceans from East Africa to Hawaii, and from Japan to Australia. A few, like Hydatina physis are found all around the tropics, including the Pacific and Indian Oceans, the Carribean and mid Atlantic Islands. I am just putting some pictures on the Forum of species that are found only in Antarctic waters, which clearly shows that wherever there is sea water, you are likely to find Sea Slugs.

If you look at the other questions and answers on this page, (below yours), you will more information about Sea Slugs.

I hope this will help,
Best wishes,
Bill Rudman.

Dear Ross,
I don't know if you actually found the Sea Slug Forum. If not, have a look at some of the topics listed on the GENERAL TOPICS page.

Also have a look at the LIST OF SPECIES oage. All the species listed under ORDER NUDIBRANCHIA are nudibranchs - so you will find a lot of information there about the variety of shapes, colours and lifestyles that nudibranchs have.

You will also find a lot of general information in the other messages below yours, on this page. if you have some particular questions you would like answered please let me know.

Best wishes,
Bill Rudman.

Dear Brehan,
I guess there is no short answer to such a question... but I'll give it a go. Firstly, to be a biologist you need to be fascinated by life in all its forms, and all its activities.

Why study nudibranchs? Have a look at some of the many examples displayed in the pages of the Forum to show their amazing diversity of shape and colour. Go to the the GENERAL TOPICS section and look at some of the many fascinating ways they have modified their bodies for defence and feeding.

Nudibranchs, and other related Sea Slugs, are snails which have, or are in the process of, losing the snail's key organ of defence - the shell. In many ways the evolution and diversity of Sea Slugs is driven by this loss. Three examples you should particularly look at are Solar powered Sea Slugs, the aeolid cnidosac, and Colour in Sea Slugs.

I don't know of any other group of animals which are so beautifully coloured and have so many fascinating stories to tell about their evolution and ecology. That's reason enough for me.

Perhaps some other participants in the Forum will let us know why they study nudibranchs.

If you can send a photo or drawing of the nudibranch your professor found perhaps someone can tell you something interesting about it. Could you also tell us where Lopez Sound (San Jose) is? California perhaps? The Worldwide Web certainly makes the world seem smaller - but not so small that I in Sydney, Australia can know where Lopez Sound is, or which of the many San Joses around the world is yours.

Best wishes,
Bill Rudman.

Dear Sean,
I haven't had a chance, as yet, to prepare the pages I had planned to do on basic topics such as the anatomy and basic biology of Sea Slugs. If you have a look at the GENERAL TOPICS list you will find some aspects of their life discussed and described, but there are big gaps.

I would suggest you should have a look at Bernard Picton's Nudibranchs of the British Isles which has information on feeding and reproduction. It only covers the carnivorous nudibranchs. Of the other major groups, the Sea Hares (Anaspidea) and Sacoglossans are herbivorous, and the Cephalaspideans and Notaspideans are specialised carnivores. If you go to the SPECIES LIST you will examples of these other Sea Slugs.
Best wishes,
Bill Rudman.

Dear Christian,
I'm glad you find the Forum useful. New material is being added all the time and hopefully I will get time to add some anatomical pictures. If you or your diving friends have photos and observations you would like to put on the Forum site, I would be glad to have them.

To answer your questions:
* What is the duration of life for a slug?
Most species seem to live for about one year, although the tropical Sea Hare Dolabella auricularia can live for six years in an aquarium and the Antarctic cephalaspidean Philine gibba can live for up to four and a half years in nature. On the other hand there are small nudibranchs, especially those that live and feed on short-lived cnidarian colonies which have extremely short life cycles. For example both the European aeolid Tenellia pallida and the coral-eating tropical aeolid Cuthona poritophages can mature in three weeks, and probably die within two or three months.

* Is it possible that some different species could procreate?
I guess you are asking whether different species can mate together. There is no evidence that I know of different species mating together. In fact I have many times confined different species together in small containers, and while animals of the same species often mate in confined spaces, I have never seen different species do so. They appear to have good chemical signals to identify their own kind.

* Approximately, how many different sort of eggs presentations did you know?
If you have a look at the list of GENERAL TOPICS you will see that a number refer to eggs. Also use the "Search the Forum" button on the right side of the yellow bar at the top of this message to look for other references to eggs in the Forum. At some stage I plan to prepare a page on different types of egg masses, but I haven't had time as yet.

* What are the normal season for reproduction?
In temperate waters they normally breed in early spring and sometimes there is a second period of egg-laying in late summer. In tropical waters egg-laying is also often seasonal, but can also be dependent on food supply, some species apparently breeding throughout the year.

* Where I could find information on the web about defense system and anatomy picture of slug?
Have a look at the GENERAL TOPICS page on the Forum. There are a number of pages devoted to Opisthobranch Defence. I'm afraid I don't know of a website with good anatomical drawings.

Best wishes,
Bill Rudman.

Dear Kathie,
Thanks for your supportive comments. They are always welcome! If your daughter has specific questions she wishes to ask, if she sends them in I am happy to have a go at answering them. To a large extent the content on the site is growing in reponse to "audience" demand. Some topics and groups are better covered because that's what I am being asked about.

Best wishes
Bill Rudman