challenging snail ID - any experts?

Flashy Fins · Jul 30, 2015

I bought this "nasarius" snail a couple of years ago and have since noticed the decline, and now complete absence, of all other snails in my tank. It could just be that time has done its job with the others (how long do snails live?), but it seems suspicious that I used to have trochus, other nasarius, and loads of collinistas, and now none. I did have a bumble bee snail, which I know are carnivorous, but he was a hitchhiker I decided to keep, since he never seemed to disrupt the others' numbers enough to notice. I haven't seen him or any other snails in the last 6 months, at least.

The snail in question is about 2.5" long, larger than any nasarius I've had before (including the super Tongan "butterscotch" species). It doesn't have eyes like a conch. It sometimes sleeps in the sand and other times sleeps on rocks; same goes for his cruising style. I kept him around, because I witnessed him eating cyano a couple of times, but he doesn't do much of that, and my tank is really in need of some algae eating snails. I do have a tuxedo urchin who's been in the tank from the start, but he can only do so much.

With some new trochus and nasarius snails in quarantine, I figure I need to pin down an ID for this potential killer while I have time. If I can't get an ID, I'm going to remove him to be on the safe side, but I'd prefer to know what it is before passing it on to anyone else or needlessly killing it. Anyone know?

Shep · Jul 30, 2015

Not sure, [HASHTAG]#reefsquad[/HASHTAG] might know

kschweer · Jul 30, 2015

It could Possibly be a whelk which are carnivorous.

Bensadork · Jul 30, 2015

A picture would help anyone on this site vastly in trying to ID a snail. A picture is worth a thousand words, especially when trying to figure out what something is.

Flashy Fins · Jul 30, 2015

Bensadork said:
A picture would help anyone on this site vastly in trying to ID a snail. A picture is worth a thousand words, especially when trying to figure out what something is.

I agree. There is a photo. Can others not see it?

143MPCo · Jul 30, 2015

Good resource-->http://melevsreef.com/whelk-versus-nassarius

What is the difference between a whelk and a Nassarius snail?

The creature on the left is a Nassarius, the one on the right is a whelk. Whelks get much larger, while Nassarius don't.

If you look at the texture of their snouts, there is a specific pattern "tattooed" onto the flesh of the Whelk. Also, the Whelk has a protective shell on its tail that it uses to seal itself in its shell when in danger. This gives it a water tight seal.

Whelks don't travel too quickly, in my experience. By comparison, Nassarius glide across the sand exceedingly fast, moving on a large foot that allows them to move forward effortlessly.

Also, the feeler or eye stalks appear to be longer on the Nassarius snails, when you compare them to the Whelk's extended appendages.

Lastly, the shell. Of all the whelks I've caught, every one of them looked like this one, with the darker coloration with whitish patches. In 48 hours, I caught 71 of them. Over the next year, I've caught at least 50 if not more. No special efforts need to be made to breed these, as they seem to do so quite easily on their own. They can be super small (1/8" long) or reasonable large (1" long), depending on age and growth. The ones pictured to the left are very small.>

Nassarius snails are excellent for DSB owners, because they submerge themselves and move through the sand keeping it stirred. Occasionally an observant person will see their little snout poking up like a periscope. When food hits the water, they come out of the sand and seek food hungrily. They will climb the glass at times.

Whelks act like snails, and tend to be on the glass or rockwork. They will move across the sand when necessary, but never submerge themselves beneath the surface of the sand. Their main activity can be observed at night by flashlight, as they are nocturnal creatures. They eat clams, so if you have clams you don't want whelks! Even though they were in my tank for over a year, they never bothered a single item and were excellent as part of the clean-up crew. However, one day I added a new clam and overnight they killed and consumed the entire thing in a few hours. I want to keep clams too, so they must go.

Shep · Jul 30, 2015

143MPCo said:
Good resource-->http://melevsreef.com/whelk-versus-nassarius

What is the difference between a whelk and a Nassarius snail?

The creature on the left is a Nassarius, the one on the right is a whelk. Whelks get much larger, while Nassarius don't.

If you look at the texture of their snouts, there is a specific pattern "tattooed" onto the flesh of the Whelk. Also, the Whelk has a protective shell on its tail that it uses to seal itself in its shell when in danger. This gives it a water tight seal.

Whelks don't travel too quickly, in my experience. By comparison, Nassarius glide across the sand exceedingly fast, moving on a large foot that allows them to move forward effortlessly.

Also, the feeler or eye stalks appear to be longer on the Nassarius snails, when you compare them to the Whelk's extended appendages.

Lastly, the shell. Of all the whelks I've caught, every one of them looked like this one, with the darker coloration with whitish patches. In 48 hours, I caught 71 of them. Over the next year, I've caught at least 50 if not more. No special efforts need to be made to breed these, as they seem to do so quite easily on their own. They can be super small (1/8" long) or reasonable large (1" long), depending on age and growth. The ones pictured to the left are very small.>

Nassarius snails are excellent for DSB owners, because they submerge themselves and move through the sand keeping it stirred. Occasionally an observant person will see their little snout poking up like a periscope. When food hits the water, they come out of the sand and seek food hungrily. They will climb the glass at times.

Whelks act like snails, and tend to be on the glass or rockwork. They will move across the sand when necessary, but never submerge themselves beneath the surface of the sand. Their main activity can be observed at night by flashlight, as they are nocturnal creatures. They eat clams, so if you have clams you don't want whelks! Even though they were in my tank for over a year, they never bothered a single item and were excellent as part of the clean-up crew. However, one day I added a new clam and overnight they killed and consumed the entire thing in a few hours. I want to keep clams too, so they must go.

Based on that link I would say its a Whelk

Flashy Fins · Jul 30, 2015

I had those same small, dark whelks in my tank a few years ago and plucked them all out. I posted an image online and got a positive ID, then removed them. (It was a couple of years before the current bout of missing snails, so no overlap.)

This snail is definitely not that species of whelk (could be another, although it's all-over light in color), but it's also not one of the typical nasarius species sold for tanks. There is no pattern on the stalk, or if there is, it's faint enough that I've never noticed it.

There are some killer nasarius snails in the ocean (according to Coral magazine), but not the ones we keep in tanks. This was one of a kind in the sales tank, probably a snail not intended to be collected, so it's been difficult to find anything that matches up exactly, be it a nasarius or other type of whelk. It was foolish to purchase an unidentified snail, but at the time, I assumed it was a good one, since the larger Tongan nasarius I'd had in the past did such a good job keeping the tank clean.

Hoping someone comes along and can positively ID it, but either way, I think his days in my tank are over.

Flashy Fins · Jul 30, 2015

The article mentions this:

Also, the Whelk has a protective shell on its tail that it uses to seal itself in its shell when in danger. This gives it a water tight seal.

However, I think both nasarius and other whelks have a version of that seal. If you look closely at the photo here, you can see it:
http://www.liveaquaria.com/product/prod_display.cfm?c=497+526+1133&pcatid=1133

It's more noticeable in person, but only to those who stare. I keep a separate QT for inverts/corals, so there isn't much action to witness in there, and I find myself noticing small details.

Bensadork · Aug 2, 2015

Oops the picture didn't pop up earlier when I read the post

Reefing Madness · Aug 2, 2015

Whelk Snail

Flashy Fins · Aug 2, 2015

Yes, it's either a whelk or other type of carnivorous nasarius not normally kept in tanks, but which of the many? Tough for a layperson to give an answer, but occasionally there are people on forums with strange careers studying these things; that is how I got my last whelk invader ID'ed to species level.

It occurs to me this snail is also the reason I so rarely see bristle worms anymore, when my tank used to be full of them. He's definitely getting evicted as soon as I can reach him. I figure I'll offer to my local club as a snack for a puffer or other snail-cracking fish, rather than tossing him in the trash. Can't think of any other use for him.

ritter6788 · Aug 2, 2015

Looks like some of the carnivorous snails we have in the Gulf of Mexico. I got a bunch of them once to feed my peacock mantis shrimp. Someone ID'd them as Florida rock snails. Likely something along those lines. I kept them in a tank and fed them table shrimp, the larger ones can eat one whole.

ritter6788 · Aug 2, 2015

These were the ones I had.

http://www.gastropods.com/4/Shell_1904.shtml

Harold Green · Aug 2, 2015

I went through this years ago with a different type of snail. I bought some large snails that were covered with a beautiful pink coralline algae. After a couple of weeks I began to notice my large turbo snails were disappearing. The pink snails were hunting them down at night and eating them. Now I'm much more careful in the snails I add.

Flashy Fins · Aug 2, 2015

ritter6788 said:
Looks like some of the carnivorous snails we have in the Gulf of Mexico. I got a bunch of them once to feed my peacock mantis shrimp. Someone ID'd them as Florida rock snails. Likely something along those lines. I kept them in a tank and fed them table shrimp, the larger ones can eat one whole.

ritter6788 said:
These were the ones I had.

http://www.gastropods.com/4/Shell_1904.shtml

Thank you! Some of those definitely look like mine. A whole table shrimp, eek! Makes me glad I don't have fish in the tank; I suspect the 1" gobies I've kept in the past would be dinner if caught while sleeping.

Flashy Fins · Aug 2, 2015

Harold Green said:
I went through this years ago with a different type of snail. I bought some large snails that were covered with a beautiful pink coralline algae. After a couple of weeks I began to notice my large turbo snails were disappearing. The pink snails were hunting them down at night and eating them. Now I'm much more careful in the snails I add.

Yeah, lesson learned. I've stopped buying nerites that crawl out, astreas that can't get up, and unidentified snails that might turn out to be murderers. Trochus for algae and specific types of nassarius for uneaten food are a good mix.