Badman's Tropical Fish

All-Water Boards => Other Aquatic Pets => Topic started by: Aquatot on March 12, 2015, 08:45:15 AM

Title: MTS evading predators
Post by: Aquatot on March 12, 2015, 08:45:15 AM
Has anyone else ever noticed that Malaysian Trumpet Snails seem to know when there's a predator in the tank? I've come across this a few times over the years, but figured maybe it was my imagination. I know when I moved my trio of striatas out of the 20gal and into the 150, suddenly snails began to appear who I'd assumed had been long ago eaten by the loaches.

Yesterday, I moved a baby clown loach out of the QT tank and into the 150. It's actually my betta tank, but I haven't yet replaced Chiaro so have been using it for quarantine to keep the filter active. I'd begun to notice a few MTS in this tank, which is rather annoying as I'd hoped to keep this one tank MTS-free. I really don't want another tank over-run with the little buggers. I'd been picking them out when I could and trying to keep on top of the growing numbers before they got out of hand. Then I bought a new loach and quarantined him for five weeks. I figured (hoped) maybe he was taking care of the MTS while he was in there. I didn't see any the whole time he was there.

Within a couple of hours of moving him into his permanent tank, suddenly there were snails appearing again. Live, uneaten, varying sizes of MTS, appearing in the sand, on decor, climbing the tank walls again. I honestly hadn't seen any of them while the loach was present. As soon as he was gone, there they were again.

I'm not imagining this, right? It's got to be the third or fourth time I've seen snails miraculously reappear as soon as loaches are removed. They know! They have to. But they're not remotely bothered by any of the non-snail-eaters in my two over-run tanks. And I NEVER see a snail in the 150 (my loach tank), even though I do find them in the filter when I take it apart.

How do they sense predators? How do they know a clown loach will eat them, but a cory won't? It's like the word gets out - 'phew, he's gone guys, it's safe to come out now'. Obviously, this makes sense from an evolutionary standpoint, but how do new generations of tank-bred snails know that loaches mean danger?

Title: Re: MTS evading predators
Post by: Keith W on March 12, 2015, 10:41:05 AM
Instinct?   :happy:

Scoop them up for the loaches... Yum.


Title: Re: MTS evading predators
Post by: Pat Mary on March 12, 2015, 12:02:39 PM
That's very interesting, Tot.  Maybe the predators put out some chemical or something that the snails can sense.  It seems to me that in nature, creatures somehow develop sensitivities that allow some of them to survive for the good of the species.  I never thought that snails had any intelligence to speak of so there has to be something else that warns them.

Title: Re: MTS evading predators
Post by: Aquatot on March 13, 2015, 09:45:26 AM
That's what I've been thinking, Pat. Of course there's instinct involved, Keith. ;) It's what triggers that instinct that fascinates me. It's not like all baby snails get shown a diagram of botia species that they must avoid, like little kids getting taught about stranger danger.

Yes, maybe some sort of pheromone, or some behaviour that only loaches exhibit that the snails perceive as threatening. Or maybe they just see a few of their pals getting eaten which triggers the instinct to hide before they're next. What amazes me is the speed with which they all come out again when it's safe. I wonder if this behaviour has ever been studied properly?

Title: Re: MTS evading predators
Post by: Netti on March 13, 2015, 12:03:00 PM
That's a really interesting observation Aquatot. Maybe it's what an attacked snail exudes that warns the rest of them?

Title: Re: MTS evading predators
Post by: Spuds on March 13, 2015, 12:16:03 PM
Yeah its interesting... doing a module on animal behaviour.... we looked at aquatic snails few weeks back and they respond to predator cues... Fish Pheromone's and dead crushed snails can make em go into 'anit-predator' mode.

What was also interesting they found that snails which were taken from a water body without fish (same species different location) which preyed on them they didn't respond as much to the cues.. So not just instinct... they also learn a develop these behaviors from their environment.

Sure when i used to have assassin snails all my MTS disappeared... when i removed them they appeared out of nowhere  ;)

Title: Re: MTS evading predators
Post by: Aquatot on March 14, 2015, 08:50:19 AM
Wow, fascinating, Spuds. It's especially interesting that this can be learnt behaviour... shelled molluscs may have more intelligence than we give them credit for.

It's weird, though, because the snails in my QT/betta tank have never encountered a predator before. My 150 is the only tank with snail predators (clown loaches, yoyos, and striatas), and it's unlikely these snails came from there (like I said, I never see any in the tank itself). Well, who knows for sure where they come from... but I suspect a couple of babies were introduced some time ago and have since bred.

Presumably they come back out again as soon as the predator's pheromones are gone from the environment? The chemical signals must not hang around in the water column for long.

Or, like Netti said, could it be that the snails themselves give off some sort of distress hormone when they're attacked, and this warns the others? That said, I haven't found any empty or crushed shells yet, so I'm not sure whether the little loach managed to get any escargot during his stay...