Nassarius, or whelk?

iwishtofish · #1 12/03/2007, 10:49 PM

One of my scarlet reef hermits molted this evening, and I think it must have been a bad molt. First another smaller hermit began to give him trouble, and now two of my nassarius snails have him smothered and may be killing him. He attempted valiantly to battle them off, but they were brutal in their persistence.

Now I am wondering if they are really nassarius snails as I requested when they were sold to me, and not the evil whelks. I know there are white nassarius, and then the darker ones. A friend of mine has white ones that are a good bit larger.

Can anyone help with the ID?

iwishtofish · #2 12/03/2007, 10:52 PM

Oh my. Talk about a brutal scene. They have him out of the shell and one is chasing him down.

pagojoe · #3 12/04/2007, 02:04 PM

Yep, your snail is a Nassarius, although it's not one of the species usually implicated in killing live animals. They can sense the body fluids in the water, and are attracted to anything that might be food, even if it's not decomposing. A crab molting or a Stomatella dropping part of its foot probably "smells" the same way an animal smells when it's been ripped apart by some predator. Consequently, your snails go on the hunt, and will finish off any vulnerable animal they can reach. It's life on the reef, and an adaptation that is at least partly responsible for the success of the family Nassariidae...there are several hundred species in the family.

http://www.gastropods.com/9/Shell_3309.html

Sorry about your crab,

Cheers,

Don

TWallace · #4 12/04/2007, 02:29 PM

I had a cleaner shrimp die last week and my Tonga nassarius snails rose up from the sand and smothered the corpse. I think this is totally normal behavior for nassarius.

iwishtofish · #5 12/04/2007, 03:16 PM

Thanks for the ID, pagojoe. He was a bad crab - I think he had it coming. TWallace, I had one jump on my dead blenny pretty quickly, too. They definitely don't miss a chance!

webbstock · #6 12/04/2007, 03:41 PM

I have the identical nass. snails currently in my tank. They are crazy aggressive. I'm afraid to dip a finger in my tank...

luke33 · #7 12/04/2007, 03:42 PM

Yea, Nassarius snails will eat crabs fish, there opportunistic and if there's not alot of food they will go after these kind of things. I've even heard of them killing anem's.

iwishtofish · #8 12/04/2007, 06:59 PM

Anemones! WOw - maybe I shouldn't have dropped them in the tank in the first place!

plummike · #9 12/04/2007, 08:29 PM

The aggressive nature and hardy appetite makes them good tank cleaners. Think of all the sand stirring and waste they eat. Everything has bad points.