Invertebrates: Molluscs – Gastropods (aka…Snails)

Today’s blog features snails from the class, Gastropoda.  I believe nudibranchs (sea slugs) from the same class deserve a blog all of their own, so that will come out soon.  I have included reproductive capability (if known) for many of the species to provide an idea which snails are most appropriate for a home aquarium.  The snails are in no particular order.
Cerithium sp. (Cerith Snail) – Reef Safe
Cerith snails are a beneficial part of a reef tank clean-up crew.  They reproduce in captivity to some extent (some aquarists have more success than others, and juveniles make it to adulthood in small numbers).  The egg pattern is very distinctive, as shown below.
Cerith snails laying eggs
Stomatella Snails – Reef Safe
Stomatella snails are one of my favorite hitchhikers.  They often come in on live rock or corals, and do well in the home aquarium.  They reproduce in captivity and will fill an aquarium with babies relatively quickly if there is a lack of predators.  Their shell is shaped like a fingernail which leaves them vulnerable to hermit crabs and other predators (however, they can lose their tail like salamanders can in self-defense).  They’re most active at night, and it is not unusual to find them perched on a high rock in the middle of the night releasing what appears to be small puffs of smoke (they’re broadcast spawners.) 

Strombus alutus (Conch) – Reef Safe

If you are looking for a snail with a bit of a personality, then I suggest the “fighting conch”.  They often submerse themselves below the sand with an eyeball or two sticking up to watch their surroundings.  They’re great algae-eaters and sand-sifters.  I had (what I assume to be) a mated pair that regularly laid eggs.  Unfortunately, I never had success raising these in captivity.   
Conch Eggs
This is another species of conch (not exactly sure which species), but the photo shows the eyes/proboscis structure.
Astraea sp – Reef Safe
These snails annoy me the most – so much so that I have to question how they aren’t extinct.  They frequently tip over and have no ability to right themselves thus being easy targets for predators.  I would avoid this snail unless you have enough time to flip each one back over constantly or enough money to keep buying more.
Astraea phoebia (Ninja Star Snail) – Reef Safe
I occasionally see these for sale, and of course, I shelled out the extra cash for a “really cool looking snail”.  In my opinion, they’re neat, but not worth the extra expense.  I am not aware of their reproductive capability in captivity.

Nerita sp. (Nerite Snail) – Reef Safe

Nerites are my first choice to purchase (when I actually do purchase snails).  I prefer to let snails reproduce in captivity, but these are great until an active reproducing snail population is established by other species of snails.  Nerites lay eggs very frequently (small white dots), but unfortunately, I only know of one case personally where a hobbyist was able to get the eggs to grow to adulthood.  The only downside to these snails is that they prefer tidal zones, so they will hang out toward the top of an aquarium.  I’ve found quite a few that managed to escape before, and it’s not pleasant.

Nerite Eggs

Vermetid Snails – Reef Safe with Caution

Vermetid snails are one of my worst enemies.  They are stationary snails as adults and build permanent tube structures on the reef.  To catch food, they extend a sticky mucus strand and reel it back in to eat the particles.  They aren’t exactly harmful to a reef, but the mucus strands may annoy corals and detract from their physical appearance.  And, while they may not be harmful to a reef, they are harmful to soft skin!  Picking up a rock with these sharp tubes may cause significant pain/injury and even infection.  Use caution when working around these hitchhikers. 

Nassarius sp – Reef Safe

Although Nassarius snails are reef safe, there are whelks (predatory snails) that look very similar.  Nassarius sp. are great sand-sifters, and they have an amazing sense of smell.  Within seconds of adding food to an aquarium they will surface from the sand and head straight for the food.
Collumbellid Snails…AKA Hawaiian Strombus Snails…AKA Strombus maculatus – Reef Safe
Ok, so maybe the taxonomy isn’t entirely straightened out on this snail yet, but regardless of name, they’re great snails.  As you can see by the egg sacs (with some juveniles emerging) below, they reproduce faster than rabbits.  If you’re sick of buying snails, then these are your best choice in my opinion.  They graze over rocks and on glass, stay small, and their population waxes and wanes with food supply. 
Collonista Snails – Reef Safe
Most reefkeepers have probably run across the Collonista snail at some point or another – likely as a teeny speck of a snail on live rock or on the glass.  These reproduce in captivity faster than the Columbellid snails in my experience, and it isn’t unusual for them to just about cover every surface at night.  For whatever reason, I rarely see them grow larger than a seed bead, but I have had some grow over the years to about the size of a pea. 
Turbo Snails –  Reef Safe
These are the bulldozers of the snail family for a reef aquarium.  These snails grow very large and have voracious appetites to match.  Not surprisingly, they are not graceful creatures and will bump rocks and corals over.  Beware of these snails if you have an overflow as well.  Their shell diameter seems just perfect for clogging plumbing and allowing tanks to overflow.  (Yes, it happened to me!)  Many aquarists believe Collonista snails are juvenile turbo snails, but they are a separate species.  I have not had success with turbo snail reproduction.   
Margarita Snail – Not Responsibly Reef Safe
Last (and least), we have the Margarita (or Margarite) snail.  Sadly, these snails are taken from colder water, given a tropical-sounding name, and sold as tropical species.  They slowly cook internally over a few weeks to months then perish.  Please do the responsible thing and discourage import of these colder water species by not purchasing them.  There are much better choices, especially the reproducing species.  I was recently informed that some brought into the country many years ago were from warmer climates, and they survived quite well.  However, that no longer appears to be the case. 

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  1. Invertebrates: Egg Identification » Reef'd Up Aquatics

    […] Cerith snails are a beneficial part of a reef tank clean-up crew.  They reproduce in captivity to some extent (some aquarists have more success than others, and the juveniles make it to adulthood in small numbers).  The egg pattern is very distinctive, as shown below with the mother (and possibly father).  The egg pattern will vary by species, but most have something similar to this white swerving pattern.  More info on snails […]

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