Mactan Island, The Philippines
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When deciding upon snail species to add to our aquariums, I have found through observing where the various species are found in nature that we should consider the habitat that we are creating within our aquariums. There are a great many species of snails that are not found in the rocky habitat that most reefs and our aquariums are. As an example, the commonly sold Astrea snails are found by me, inhabiting the sea grass beds where they spend their time cleaning the blades of the larger sea grass types. Their cone shaped shell is not suited for rocky habitats as they are unable to right themselves if they become lodged in a rock crevice, making them even more vunerable. I say more vunerable because the usual small crabs, mantis shrimp and predatory worms that live within rocky habitats are not normaly found in a grass bed environment, to do so, would make them vunerable to predators as well. As such, I believe the snail species that do not have a "trap door", such as the astreas, have evolved no defense or a suitable shell design since they do not frequent rocky environments. Which makes them unsuitable for our aquariums. The "trap door" species such as the "star" and "turbo" types are found in rocky habitats and have evolved suitably shaped shells and defensive "doors" to ward off predators such as worms, crabs and mantis shrimp. To further this arguement, I have kept mantis shrimp in my aquarium and have noted that they pay the "trap door" snail species no attention at all, but let me put a vunerable astrea into the aquarium, and they quickly grab up the snail and run off into hiding with it, and moments later you can hear the tell tale "thumps" as the mantis goes about cracking open the astrea snails entrance , enlarging it to gain access to the snail itself.
Please note, that if your snails came from an aquarium that also held fish or shared water on a common filtration system with fish, there is a good chance of the snail bring in the Ich parasite as the trophont stage attached to the snail's shell. If you find this to be the case, I would consider putting your new snails into a quarantine tank and keep them there for at least six weeks.
Newly Purchased Snail deaths - With what seems to be a fairly common occurance when adding new snails to our systems, it is often asked why a newly added snail will just sit in one spot and not move for days. A good many of them will also be found to have died in that spot as well. Listed below and in order of being the most likely cause(s) are a few things to consider when purchasing , as well as when adding snails to our aquariums.
Acclimation. As with most other invertebrates, snails are very sensative to any sudden changes in temperature, salinity and pH, along with just being put into "different" water is a good way to stress them severly. When following an acclimation procedure, I would double the length of time and use a much slower water addition method such as a very slow drip. Also ensure your aquarium's water quality is at "reef" grade levels, meaning that ammonia is undetectable and nitrates are at .05 or below.
Species Selection. It is a far too often practice of collectors to "discover" an abundance of algae eating snails within near shore areas of their residences and decide to cash in on the easy pickings. Of course if the ocean near their home happens to be a temperate or cold one such as found on the pacific coast of the United States, then those species collected from such locales will not be suited to survive in our tropical aquariums. Please be sure when you purchase snails that you yourself get a species identification and research that species range as found in the wild. Do not rely on a suppliers identification as the vast majority of the time, they are not even close, plus having the tendancy to call all rounded snails "turbos" is not much help either. I can not stress the importance of correct identifications enough to ensure you have a suitable species. Buying a "conch" thinking it will eat algae only to find out later that it is actualy a whelk species that preys upon other snails is all to common within this hobby.
Food Sources. While a good many herbivor snails do consume a wide variety of algae, there are also a good many species that are very selective in the algae types that they will eat. Again, this is where species identification and study of that species is needed. Another often missed item is in our aquarium's ability to produce the type and amounts of algae needed by each individual snail. It is quite easy to overstock the aquarium with too many snails and have them starve to death over the course of a few months. When establishing a snail population, I would start out with ten snails per 100 gallon tank size and give them two months to see how they are coping with what algae your aquarium produces. If they are not keeping up with their duties, add ten more and give them another two months and repeat as needed. Far to often suppliers (stores) recommend adding a hundred snails at one time as a "starter" clean up crew. And what happens when half or more of them die and you dont notice it right away?
Get to know the real Ilyanassa obsoleta - Ebay buyers beware!
After having collected many herbivore snails from the wild, I have found that the ringed cowry to be the best suited for life within our aquariums as well as having a wide range of algae that it finds as an acceptable food source, including green filament algae (hair algae). If you can find these for purchase, I would highly recommend them.
A ringed cowry with its mantle fully extended
A ring cowry brooding a clutch of eggs, of which the snail will remain as such untill the eggs hatch out.
Nerites - The main diet of most nerites is diatoms that grow as a film coating rock surfaces in the intertidal zone. Nerites also feed on filamentous and film-forming cyanobacteria, and filamentous green algae.
The Predatory Snails - A group whose representatives are seldom found in our home aquaria, although every now and then some of them do make it into aquaria, either as involuntary hitchhikers or as acquisitions. These are the shelled snails that are predatory on other animals.
The Grazing Snails Part Two Part Three - It is always worth the reader's time to remember that no two species have the same requirements. Each species is special and unique in its own attributes, and discussions of generalities can go only so far.
The Whelks - All of which are predators. Several things must be taken into account when trying to determine if the mystery snail in an aquarium is, or is not, a whelk.
Snail Reproduction - Some snails, including many of the so-called “turbo-grazers” found in reef aquaria are broadcast-spawning animals. At the complete other end of the spectrum are numerous snails, mostly living in fresh water, that give birth to live young.
Gastropods.com Taxon Pages by Common Name - Usefull for those of us who are not familiar with scientific names.
Gastropods.com Taxon Pages by Family Name - A very extensive listing of snail family groups, although you must know the scientific family names.
Snail Hitch Hikers - My own page showing some of the commonly found species that arrive hiding within live rock and live sand.
Commonly Kept Snails - Another usefull page also listing some of the commonly found and kept snail species.
A few of the more unusual finds for me :
Scutus sp. - One of the more unusual marine snails, related to limpets. Reef safe algae grazer.
Abalone - A harmless herbivore and is distinctive by its "holes" evident in its shell.
Used by permission. Many thanks to Charlies and Linda Raabe for their support. www.chucksaddiction.com