Dear Biju,

These are all Aplysia oculifera. The name 'oculifera'  means 'bearing eyes' which refers to the small black rings which could be compared with eyes. In the close-up alongside, the true left eye is not the  black-ringed white spot behind the left head tentacle [rhinophore] but the black spot which I have ringed with white.

Best wishes,
Bill Rudman

Dear Vishal,

I am pretty sure these are Aplysia oculifera. You will see from other photos on the Forum that this species usually has small brown 'eye rings' [which give it the name oculifera] but in your specimens they are just small brown spots. However each brown spot is sitting on a translucent brown patch, which is just the same as the brown rings in more typical A. oculifera. That species often has quite a dense covering of small white spots. Although not as plentiful in your animals, you can certainly see them in your photos. The animals is your lower photo certainly appear to be mating

Best wishes,
Bill Rudman

Dear Zubi,

I suspect there are more names for sea hares than actual species. Most species have been named from one or a very few animals from a single location which doesn't allow for very much colour variation which we know occurs in these animals. If we look at photos of Aplysia dactylomela on the Forum we find a range from animals with very large open rings to others with small rings [see #20921] which could almost be identified as A. oculifera.

As I discuss in other places on the Forum, Aplysia kurodai was not very well described and as there are many species with a colour pattern of brown and white mottling. From photos I have seen it seems that what is called A. kurodai in Japan is a swimming species with relatively thin parapodia. Your photos seem to be of animal with thicker more rigid  parapodial flaps - more like A. dactylomela and A. oculifera. Also the colour pattern of dark and light bands on the inside of the parapodia is also more similar to A. dactylomela and A. oculifera. The scattered brown patches on the parapodia, which I have ringed, remind me of the brown background for the eyespots in A. oculifera. I suspect your animals are a colour form of A. oculifera, or even A. dactylomela.

Best wishes,
Bill Rudman

Dear Corvin,

Your message arrived after I had posted my comments on #20249. I'm glad my identification coincided with Annette Klussmann-Kolb's. I assume the three photos you attached represent the three supposed species. If so the top one is A. dactylomela and the bottom one - just the head - is A. oculifera. This leaves the middle one - the mating pair - as unidentified. I think at this stage it would be useful if you could send photos of these three 'species' as separate messages. It would be useful if you could include a juvenile and adult photo if you have them, and a side shot so we can see how far back the parapodia go.

The problem is that Aplysia taxonomy is in a mess - especially in the Indo-West Pacific. As I have said before, most species were described from preserved specimens and so fitting the descriptions to living aniamls has never been satisfactorily resolved. The only attempt at a world-wide revision (Eales, 1960) is based almost entirely on preserved specimens, and extremely difficult to use for species identification.

It's possible the animals in your middle photo are a form of A. dactylomela without rings. I know you study is not centred on the animals, but I suspect you are the only one who is going to be able to sort out how many species of Aplysia you have. All I can say is see who mates with whom. That is a pretty fundamental distinction. You will also see that different species have differences in shape and relative size of the parapodia - and the parapodia join differntly at the posterior ends in different species. In A. dactylomela the parapodia join quite high just behind the mantle cavity, while in A. oculifera they stay separate almost to the posterior tip of the tail. How does your third species compare? There will also be differences in shape of oral tentacles and rhinophores, and thickness and feel of the skin - and parapodial flaps. These differences are much easier to see in living animals.

Even if we can't put a name on your third species - if there is a third species - at least you will know you are dealing with three not two species.

Good Luck,
Bill Rudman

Dear Corvin,
Thanks for the size info. If by chnace some of the small ones remain alive for awhile it would be interesting to see what they look like when they are bigger - that's if they get bigger. I suspect they are juveniles.

Best wishes,
Bill Rudman

Dear Corvin,
You don't mention a size, but it looks as though the upper animal is quite a bit larger than the ones in the lower two photos. My guess is that they are all Aplysia oculifera, which usually has a pattern of small dark brown rings. In your animals they are not clear, but seem to be there.

Sea Hares usually feed on particular species of green and red algae and quite a few feed on species of Laurencia. I am not sure if you will have much luck with them eating brown algae. Species which produce purple ink, lose the ability if they are starved of red algae. Work that has been done on larval settlement shows that metabolites in certain algae trigger larval settlement. Fortunately A. oculifera has been extensively studied Itai Plaut [see message #2444 for references]. For further information on sea hares go to the General Topics list, where there is Sea Hares link which will take you to links to a list of sea hare feeding references and another on chemical defence.

Concerning the identification of sea hares, I am afraid it is often not easy. Although most species are quite easy to distinguish from other species when you see them alive, it is sometimes difficult to put a name on them, as many species were described from preserved animals. The only comprehensive review of  species worldwide was based on preserved specimens and although the author noted the importance of colour and shape of living animals in naming new species, she proceeded to name quite a few more from decolourised preserved animals (Eales, 1960). All I can say is that as well as the colour pattern, you need to look at the general shape of the animal, size of the parapodia, whether they are joined at the back, whether there is a hole in the mantle through which the shell can be seen etc. Have a look at the pages on sea hares in the forum for background information.

However since your main interest is the algae, you probably don't want to get too involved in 'do it yourself'' slug identifications. You mention colour change. If you look at earlier messages on A. oculifera your will see some have a reddish background colour, while some which have been feeding on green Enteromorpha are quite green. It seems that pigments from the food they are currently eating can temporarily modify the colour of the sea hares.

As to them feeding on brown algae, I suspect they won't but I guess it's worth a try. How long can they starve? I am not sure, but as they tend to feed whenever food is present, I would think you would know after a week if they were not going to eat your Padina

Best wishes,
Bill Rudman

Dear Philibert,
It's nice to get observations like this on sea hare species. Although they are very common at times there is very little precise information on their biology. So every little bit of information like this is very valuable

If you have a look at the  A. oculifera larval development page. I describe some of the results of Plaut, Borut & Spira's (1995) work on larval developent and settlement of this species. They found that the planktonic larvae were triggered to settle by a variety of red algae and also the green algae Ulva and Enteromorpha, but only grew and survived if they fed on Enteromorpha. As they are known to squirt red ink, I guess they move on to red algae as they grow larger, as some other species are reported to do..

Best wishes,
Bill Rudman

Dear Sakkie,
This is Aplysia oculifera. If you look at the 'close up' I have included in the corner of your photo alongside you will see the little brown rings or 'eyes' which give this species its name. I am glad you included this photo because I would not have been able to identify it from the other two photos, one showing the typical 'inking' and the other showing how well camouflaged the often are in intertidal pools. Often you only know they are around when you look around and see purple patches in the water where you have stood on some of them.
Best wishes,
Bill Rudman

Dear Koh,
Thanks for these interesting photos. In the upper photo we can see the eggs vary in colour from green to creamy-yellow in one egg ribbon. I have included a closeup to show that what seem to be a single egg with the naked eye is a capsule containing a cluster of many eggs. The number of eggs varies from species to species in Aplysia. For example, in A. fasciata there are approx 40 eggs per capsule while in A. punctata there are only 3 or 4. I have also included another close-up alongside to show the characteristic eye spots.
Best wishes,
Bill Rudman

Dear Koh,
Thanks for these photos and those in your other messages [#13759, #13768]. We don't have many photos of this species, and yours shows the sinuous folds of the parapodia very well. I have included a close-up to show the dark rings or 'eye-spots' which give the species the name oculifera which literally means 'eye carrier'. The bright reddish pink patch on the head is the bright reddish colour of the highly muscular buccal bulb which is used during feeding.
Best wishes,
Bill Rudman

Thanks Koh,
Bill Rudman

Dear Erwin,
I am pretty sure this is Aplysia oculifera. It has the folded edge to the parapodia and although the little black rings [eye-spots] are not clear, you can see traces of them in the plain brown patches.
Best wishes
Bill Rudman

Dear Ria,
This is definitely a species of Aplysia, but from this angle I can't see enough of it to be sure what species it is. I suspect it is Aplysia oculifera. 'oculifera' means 'bearing eyes' and if you look at other photos of this species on the Forum you will see it has little 'eye-spots' on the body. So if you see this species again you shpould be able to identify it from these small eye-spots. For general information on Sea Hares, the Sea Hares Fact Sheet wiull give you many links to relevant information.
Best wishes,
Bill Rudman

Dear Jun,
Thanks very much. This is a species I did not have good photos of so it is a very welcome addition. Its name 'oculifera' means 'carrying eyes' and refers to the little brown eyespots all over the body.
Best wishes,
Bill Rudman

Dear Itai,
Thanks for making contact and for the photos from your thesis which I have put on a separate page with a summary of your interesting work on larval development and metamorphosis.

Any further information on your studies would be of great interest. By coincidence you will see that the Forum has recently received a message from Alaa youssry Moustafa who is also studying aspects of Sea Hare biology in the Red Sea.

Best wishes,
Bill Rudman.