Is this a predatory whelk?

[salty joe]

It's 1 1/2".

 

[Sophie"s mom]

I have never seen a nassarius that big, so maybe? When it’s snout comes out, is it black, or multi colored, like tattoo looking? @ISpeakForTheSeas would be able to say

 

[salty joe]

snout is black

 

[jabberwock]

I don't think it is a whelk. Leopard print on the soft bits is whelkish.

 

[ISpeakForTheSeas]

Sort of yes and sort of no at this point - it seems to be the Olive Whelk, Nassarius olivaceus, which is reportedly predatory, but there's no evidence at present (at least not that I've seen) that they hunt live/healthy critters (or that they're capable of taking a healthy critter down) - the only study I've been able to find actually discussing specifics about its diet mentioned that it did not eat a few specific live critters (including oysters):

Yeah, there's an unfortunate lack of info on N. oliveaceus' diet - I've seen it referred to as a predator in scholarly articles and I've seen numerous references from hobbyists/businesses, but looking at it, I don't think I've seen any evidence yet (scholarly or otherwise) of them taking live prey (which would be consistent with the rest of the genus).

Personally, at this point, I'm hesitant to say that it killed your shrimp, but I wouldn't be surprised to find if it's more aggressive of an opportunistic carnivore than other members of the genus (if for no other reason than its size).

 

[Sophie"s mom]

snout is black

If snout is black, sounds like a nassarius, which is great to have, I just have never seen one that big. Can you keep it in some water , but out of your tank until you get a definitive answer? @ISpeakForTheSeas would be able to say with some certainty.

 

[SomeHappyFish]

Hard to say, mine was similar to the one that jabberwock posted and it always killed new snails that I added, so I removed it.