Snail Ecology 101

[Samper]

I've been looking around and many websites that sell cleanup crews fail to list genus and species for many of their critters. I noticed hermit crab listings are even more scarce. I'd like to open up a discussion mainly dealing with snails but also anything from the Gastropod class appropriate for captivity that could be considered a "reef janitor".

The most commonly sold snails I've seen for cleanup crews are

Turbo Snails Turbo fluctuosa
Astrea Snails Astraea tecta
Nerite Snails Vittina luteofasciata
Margarita Snails Margarites pupillus
Cerith Snails Cerithium stercusmuscarum
Onyx Nassarius Snails Ilyanassa obsoleta
Tiger Turbo Snails Trochus radiatus
Tonga Nassarius Snails Nassarius arcularius
Bumble Bee Snail Pusiostoma mendicaria

I have kept at one time or another almost every one of these with the exception of the last three but I still have a hard time telling someone exactly what they're looking at if they ask. I know very little about the natural ecology of these animals. I'd like to compile some really good pictures and your personal observations of them good or bad. If anyone has anything else to add to this like another candidate for discussion please do so.

[scubadude]

You forgot one of my favs Chuck! Stomatella's


Heres a trochus

[Ninong]

The most commonly sold snails I've seen for cleanup crews are

Turbo Snails Turbo fluctuosa

That should be Turbo fluctuosus. Turbo is masculine.

Astrea Snails Astraea tecta

This name is invalid. The correct name for this species is Lithopoma tectum. I have no idea when it was reclassified. Maybe Greenbean knows?

Nerite Snails Vittina luteofasciata

There are many different species of Nerite snails (Family Neritidae) that are available for sale in the hobby but none in the genus Vittina. That is no longer a valid name. I found it referenced here as Vittina luteofasciata in a September 2003 article by Julian Sprung but that scientific name is not valid now. It may have been valid four years ago but it's not valid now.

Margarita Snails Margarites pupillus

This is a North Pacific species and has absolutely no business being sold as a reef aquarium animal! Perhaps you inadvertently selected the wrong scientific name? There are many different species of snails that are offered for sale in the hobby as "Margarite" snails. Almost all of them are inappropriate.

Cerith Snails Cerithium stercusmuscarum

Of the 20 different species in the genus Cerithium, I have found that C. litteratum is the one most commonly available for sale in the hobby; however, it's quite possible that the vendors aren't sure which species they're selling. We're lucky if they have the correct genus.

Onyx Nassarius Snails Ilyanassa obsoleta

This is not a good species for a reef tank for several reasons which we have discussed ad nauseam in previous threads. Just run a search using Ilyanassa obsoleta as the search term. It appears that Ilyanassa obsoleta is now invalid. According to ITIS, the current valid name for this species is now Nassarius obsoletus. I'm not sure when that reclassification was made but maybe Greenbean knows. I think I'll ask him.

Bumble Bee Snail Pusiostoma mendicaria

Not a good choice. Can be predatory on other snails, as has been discussed several times in the past. It appears that Pusiostoma is no longer a valid genus. It was probably reclassified to Engina but I'm not sure about that. I'll ask Greenbean if he knows.

[greenbean36191]

Wow, I guess I'm supposed to know all about these names huh? In a lot of cases the "validity" of a name is subjected and really depends on who you ask and where that person thinks the animal should be classified. Back when I was writing the Ilyanassa article, ITIS said that the name was invalid, however it's the more commonly used name in the literature, especially as of late. I suspect ITIS chose Nassarius over Ilyanassa as the valid name because it's older and AFAIK no one has published an explicit explanation of why the snail should be reassigned to Ilyanassa.

Generally I don't follow the synonymy of critters unless I'm actually writing about them though, so I don't know the history of the Astraea/Lithopoma or other reclassifications. The only thing I'd really add on the naming front is that most of the margarita snails in the hobby are Tegula spp., not Margarites. Still though, they're an inappropriate species.

[Ninong]

Wow, I guess I'm supposed to know all about these names huh?

Yes, of course!

I thought maybe you had online access at work to sources that the rest of us don't.

Back when I was writing the Ilyanassa article, ITIS said that the name was invalid, however it's the more commonly used name in the literature, especially as of late. I suspect ITIS chose Nassarius over Ilyanassa as the valid name because it's older and AFAIK no one has published an explicit explanation of why the snail should be reassigned to Ilyanassa.

I thought maybe it was a recent reclassification back to Nassarius but I just double-checked and they're citing a 1998 publicaton. I suspect you're right and ITIS is wrong. It won't be the first time they're wrong on something like this. Anyway, I just shot a PM to Ron to ask him about that.

[greenbean36191]

I do have access to just about everything and I'm usually happy to look things up, but it still takes a long time to figure out which name is the valid one. Quite honestly it just doesn't rank that high on my list of things to do ATM. Maybe if I have time in the next week.

[Samper]

Wow as usual. Having never had Latin I can barely pronounce many names much less know anything about masculine and feminine connotations. Perhaps a lesson or two would be of assistance.

Virtually all of these names were given to me by a vendor when I asked him exactly what he was carrying but they aren't the only ones listing snails under them. I don't understand how anyone can keep up with things being renamed constantly. I understand the logic behind it but how anyone keeps up is beyond me.

I was really wanting some Ecology behind the snails that are considered appropriate for reef aquaria. More specifically ones that benefit the average reefkeeper keeping a system <200 gallons. Perhaps you could list your recommendations for this and why?

[Ninong]

I believe trochus snails are probably the most valuable snails for reef aquaria. After that, it's pretty much a matter of personal preference as long as you realize that many of the species offered in the trade are not suitable for various reasons.

Nerite snails are OK but they do tend to hang out at waterline at the top of the tank during the daytime. I think they're mostly nocturnal. Cerith snails are nice, especially if you have a sand bed. If you have a sand bed, Nassarius snails are good provided you don't overstock them. Nassarius vibex are the ones you should look for. These snails are carion eaters, so how many you need depends on how much carion, and meaty detritus, you expect to have in your tank. Most people get too many of these.

Stomatella varia are nice and they will reproduce in your tank. The little snails that IPSF sells as Strombus maculatus are nice but very small (1/2" max). They, too, will reproduce in your tank. BTW, they're definitely not S. maculatus. In fact, they're not strombids at all.

Astraea snails are problematic in that most of them have no righting reflex and cannot right themselves should they fall from the rock structure onto the sand bed. The pricey ones that Reeftopia sells as "star snails" can right themselves. Be aware of the fact that many vendors sell Astraea snails and call them turbo snails or even trochus snails. Unless you see the snails before you buy them, you often have no idea what to expect.

The large turban snails from Baja Mexico (Turbo fluctuosus) can be clumsy and knock stuff over. They can be really huge! They usually don't last very long at typical reef tank temperatures -- maybe a year, maybe a little longer. I have been told that they eat primarily diatoms. I have kept a few of them and I'm not sure what they eat. They appeared to be eating other stuff in my tank but don't forget that I have lousy eyesight.

The fighting conchs (Strombus alatus) are nice provided you have a large enough tank with a large enough sand bed surface. You probably need at least a 180-gal tank with a lot of sand bed surface to support one of these guys long-term. I had two of them in my 120-gal tank but they lasted only 18 and 24 months. I should have gone with just one instead of two. It's possible the minimum size is even larger than 180-gallons for one of these critters. They feed on diatoms and algae on the sand bed surface.

As already mentioned, the snails that are sold as Margarite snails are not good choices. These are almost always temperate species. And bumble bee snails look pretty but they can be predatory on other snails.

The snails that are known as Ilyanassa obsoleta (although ITIS insists they are Nassarius obsoletus) should be avoided. They are temperate snails and vectors for a larval stage of several fluke species. You can pick up these by the thousands on the shores of San Francisco Bay, especially in the South Bay area. They're an East Coast species that was introduced to San Francisco Bay 100 years ago. From there they spread all the way north to British Columbia but only as far south as Morro Bay. They prefer cooler waters. Water temperature in San Francisco Bay runs in the mid-50's. In fact, they can survive freezing temperatures by migrating to deeper water areas. Their natural range on the East Coast is from Nova Scotia to Florida. Their common name is Eastern mud snail and their natural lifespan can reach 60 years!

[Samper]

Thank you very much for your imput so far. It is extremely helpful. I was able to talk this particular vendor into sending me a few of each snail that he had listed even though it appears he's wrong on most of his classifications. I'm hoping to get good pictures of each of them for identification purposes.

[Ninong]

Thank you very much for your imput so far. It is extremely helpful. I was able to talk this particular vendor into sending me a few of each snail that he had listed even though it appears he's wrong on most of his classifications. I'm hoping to get good pictures of each of them for identification purposes.

Before taking any photos, you might want to read Dr. Ron Shimek's helpful hints on how to take photographs for identification purposes.