Are pond snails asexual?

[guppymill]

I have a single pond snail living in one of my tanks. It seems to be alone and is the biggest pond snail I've ever seen. It's almost a 1/4" and looks quite nice actually.

My question is, do they need two of them to reproduce?

I have lots of other pond snails in one of my other tanks, so I know what a pain they can be, particularly how they thrive in my canister filter -- yuck!

 

[guppymill]

Here are some pics of the big pond snail. He's actually closer to 1/2 an inch!
I think he's been in the tank since I set it up this February to house my male guppies.
(My ruler is in picas and inches 'cause I'm a graphic designer.)

 

[lethalcustoms00]

if thats anything like the ones i have a ton of it will reproduce all by its self

 

[Lupin]

There's an abstract explaining that the Lymnaea stagnalis needs two of them in order to trigger spawning. They're hermaphrodites certainly but need sperm exchange to trigger them to produce. I had one by itself at an inch length and never reproduced at all before it passed away much to my dismay (oddly enough) since I considered it my special snail after rescuing from a shop tank of goldfish.:22_yikes: