I second that, Thrigby is delightful. So if Heythrop still have one, and the pair at Exmoor are still going strong, that leaves three Black Leopards in the UK?
I know that Prague Aquarium (Morsky Svet) in Czech republic, had nudibranchs in their tanks from photos I saw shortly after my 2013 visit. Also when I was at Birch Aquarium (San Diego, California), there is a sign indicating certain native nudibranch inside one of the tanks, altough I've failed to see one. The problem with keeping nudibranchs is to find enough and constant quantity of their extremely special food: usually each species of nudibranch only can feed on determinate species of cnidarian. And of course we can't find these cnidarians in animal food corporations! They must be harvested regularly directly from sea in order to keep the nudibranch alive. Maybe some of the less specialized feeders can be kept just in a largue aquarium with plenty of variety corals, anemones and hydrozoans, and hope that they will feed on some of them, but for most nudibranchs this will not work: for example, the fantastic Glaucus atlanticus only can feed on Porpita porpita. So if a public aquarium wants to show something similar to a nudibranch, usually it will choose an animal that is not a nudibranch but that can be kept successfully, such as vegetarian opisthobranchs (sea hares, Elysia, Dolabrella...) or cephalaspideans (Chelidonura), that can be very colorful. Even some fabulous, very colorful flatworms (Pseudoceros, Pseudobiceros...) would be an easier substitute for nudibranchs.
True for the specialists, but there are also several less specialized species where this is not the case. For example, several aquariums keeps, or have kept, Hermissenda crassicornis and the strange lion's mane nudibranch (Melibe leonina). Neither of these have extremely narrow food requirements nor are they very hard to keep. There are really two main issues for nudibranches: 1. Many of the species that on occasion turn up in aquariums are from tropical regions and we often have absolutely no idea what exactly they feed on; sponges, corals, cnidarians, etc, are all known to be food items for various species. Being far from their native range it is typically impossible to do some food testing (collecting a few local potential food items) to figure out exactly what it feeds on. Consequently, most tropical nudibranchs that turn up in an aquarium are doomed. I know a few aquariums that got them by accident as unexpected hitchhikers on live rocks, but fortunately most public aquariums now have the common sense to not deliberately get them. In contrast to the tropicals, the food requirements for European and North American nudibranchs are typically known, and are often cnidarians or bryozoans. Some of these cnidarians are not particularly hard to find/culture and some of the bryozoans are very common. Nevertheless, very few extreme specialists have been maintained for longer periods. The Spanish shawl (Flabellina iodinea) has been kept for longer periods in several places and it is a hydroid-eater. However, those hydroids are pretty common and not particularly hard to maintain. Arguably more remarkable, Monterey has kept their local species Okenia rosacea, which only feed on very specific bryozoans. 2. Size. I could do a dive trip off Northern Europe and find one of several e.g. Flabellinidae species with relative ease. Most of these feed on very common hydroids that often are present in North European aquariums anyway. The problem: Those nudibranchs species may exceptionally reach 4-5 cm (1.5-2 in) in length, but the typical individual is less than half that size. Stunningly beautiful, absolutely tiny! There are a few exceptions of course, and the Spanish shawl and Hermissenda crassicornis are two of the northern ocean species that regularly reach 4-5 cm, making them the obvious choice for aquariums. Finally, Berghia stephanieae (sometimes in Aeolidiella and often mislabelled as Berghia verrucicornis) deserves a special mention. Many public aquariums keep this tiny species, but aquarium won't label it and in any case visitors are unlikely to see it. They are appreciated as the natural predator of Aiptsia, a small stinging sea anemone that is a menace to saltwater aquariums (both private and public aquariums). In contrast, e.g. Phyllodesmium and similar tiny nudibranchs turn up in aquariums fairly often as hitchhikers on corals, but are absolutely not appreciated as they feed on those corals! They are typically as specialized as the most specialized nudibranchs. The brightly marked tropical marine flatworms are generally specialists on certain ascidians, which themselves are much harder to keep than the cnidarians many specialized nudibranchs feed on. For this reason alone, they would be harder to keep (feed) than most of the nudibranchs.
Wow! That's a lot of info new for me, Temp! Thanks a lot for share your deep knowlegde about the artificial keeping of this fascinating groups. I was even unaware that some nudibranchs feed on things that are not cnidarians (sponges). I think that your second reason is the most important, and I didn't took it in account in my first post: generally, zoo/aquarium visitors tends to just ignore the tiny things (and even zoo staff do the same). That's why in insect houses typically only giant insects are kept (variety of stick insects, enormous horned beetles, giant cockroaches/millipedes and tarantulas...) despite many smaller and easy to keep species have atonishing colours and strange forms. P. S. Usually, those aquarists or public aquariums that want to get rid off the Aiptasia, never choose a nudibranch, but a readily available Acreichthys tomentosus or a Lysmata wurdemanni.
Thanks, Temp, extremely interesting! I wonder if nudibranchs would have trouble to adapt to artificial food if somebody tried, some form of gel with roughly similar protein content as hydrozoans? Lots of inverts are kept in labs in very artificial conditions.
That's not true. As for nudibranchs, the simple solution would be to house a population of their prey species with the nudbranchs. Plus, is there any way we can get the public to care more about small things?
As for getting people to care about small things - here in the UK Butterfly Conservatin has done a lot of good work in raising consciousness about both butterflies and moths, and I think butterfly houses could do a lot more to encourage insect conservation, but the less colourful and showy small animals are always going to have problems I think, except as part of wider habitat issues. Aquatic invertebrates are even harder to get people interested in.
Not sure I can agree on that - just think of all the nearly identical aquatic crustaceans, bugs, water beetles etc, most of which are small to minute and mostly dully colored as well.
I'll disagree with "never" since I know more than a dozen North European public aquariums that have used Berghia in the last 5 years and that's only in cases where I specifically asked keepers or know via inside sources (three got them from the university I formerly was associated with and one of those passed some on to others as they happily breed if they have enough food). There are undoubtedly more places keeping the species than the relatively few I know about, especially in North America where they generally have been more easily available (it's native to Florida). After having been relatively widely available to North American aquarists for years, they've also started being more easily available in Europe in recent years, not least due to the work of a few dedicated people such as berghia-uk. However, you are completely right that the Acreichthys and Lysmata are a more common choice. In any case this is likely a bit outside the intent of this thread; the Berghia are excellent Aiptasia killers, but not the best "display animals" due to their tiny size (typical around 1 cm / 0.5 in, although the largest individuals can be about twice that size... still tiny). That's the way it's usually done with the ones that have been/are kept successfully. The problem are those remarkable tropical species where we don't really know what they feed on, except perhaps some very general statement like "sponge" (there are literally thousands of sponge species). A secondary issue is that among the various prey groups are ones that are fairly easy to maintain in captivity, but also some that themselves have proven very hard to keep alive, notably tropical social ascidians.
To return to the nudibranchs, Monterey Bay Aquarium exhibits Lion's Mane Nudibranch and Hermissenda crassicornis. Also how about skeleton shrimps?
I didn't realise until checking ZTL that there are apparently no remora in Europe. I've seen them a few times in Asia. (Including on whale sharks maybe)
I'm sure I've seen a remora attached to a nurse shark in the nineties, but I really can't remember where? Possibly Great Yarmouth, Poole, or maybe Shirley Aquatics? 90% certain it was at one of those three.
There are; I've seen them a few times this year, including at Zoo Madrid and Pairi Daiza: ZootierlisteHomepage
