Mystery Snail Strange Mating or Aggressive Behavior

[WoadRaider]

Backstory:

Almost 6 weeks ago I received 40 gold/orange mystery snails (variety of sizes ranging from dime to a little more than a US quarter), Pomacea bridgesii. The first thing I did was attempt to sex them all by putting them upside down on a Chinese checkers board and a mancala board (for the larger ones). Due to my lack of experience and the large number of snails (hard to keep track of which were which) I was unable to accurately sex the snails; even though they were coming completely out of their shells to try to right themselves. I became frustrated with sexing and decided to instead separate them based on my judgement of their color/appearance and simply hope that I would get some of each sex based on odds.

I had seen online that you could sex them based on their outer appearance but that it was unreliable so I didn’t attempt that method. EXCEPT!! It turns out I like the lighter color/appearance of the males better because ALL of the snails I preferred (10) seem to have been male; whereas all of the snails I thought had too much dark color (I called them black tips because the back tip of their shells were dark) were female. I now realize that the dark sections are probably related to the female reproductive organ and that the snail shells are fairly transparent.

I wonder if the cause of my frustration in initially sexing the snails is that all but 2-3 of the larger ones were male and all but 2 of the smaller ones were female and so while I was checking the larger snails on the mancala board it looked like they were all the same (I thought they were male, though I was inexperienced and unsure) and while I was checking the Chinese board I couldn’t fine any that looked like males (thinking I was somehow missing the male parts due to inexperience).


The Behavior:

Until last night I had my gold mystery snails divided into two tanks based on whether or not I preferred their shell coloration. Last night I observed my largest preferred (light tipped) snail attempting to mount another light tipped snail right at the front of the tank and it just seemed to me that something wasn’t quite right; the behavior seemed too forced and desperate and unsuccessful. It seemed like the bottom snail clearly thought this shouldn’t be happening and it wasn’t productive and the top snail seemed to be frustratedly searching for something with his penis. This short duration (seemingly unreciprocated and undesired) mounting behavior is the only type I’ve seen and I’ve exclusively noticed it in the tank with the light tipped snails. The behavior has never struck me as successful mating. Before last night this behavior was always either obstructed by decorations, or happening in the back, or at angles I couldn’t see well and I didn’t want to disturb it for a closer look so I’ve never seen it as clearly as last night. My concern regarding the lack of lengthy mating, coupled with the fact that I have yet to see any mystery snail egg clutches or baby mystery snails, caused me to finally give in and mix up the preferred snails with the dark tips. As soon as I put a few of the now suspected females into the tank with the preferred snails there was a difference. Two of the suspected males were jockeying for the largest female with the smaller male currently in the best position and the largest male mostly on him. I picked them all up and took the largest male off the other two because the female was having trouble moving the 3 of them. I was happy with the apparent solution to the lack of successful mating and left to continue mixing up the snails (as well as into a 3rd tank). When I came back the largest suspected male was on top of the largest suspected female and that’s when I saw what seems to me to be the craziest most perplexing behavior (I haven’t been able to find anything close to it online after searching for hours). The largest male was holding the even larger female with his foot (while laying on his shell, maybe also on the back of his foot unsure about that) while shaking and slamming her around. He was shaking her quite violently and it stuck me as the sort of violence you might expect from a predator trying to break the shell. The only reason I didn’t intercede on her behalf was that I was so curious to see how long this was going to last and what would happen. It continued for a few minutes (I really wish my girlfriend wasn’t so busy *cough lazy cough* and would have come over with a camera) then he slowly stopped shaking her (and himself). A few minutes later he did it again; for about 30 seconds this time. I continued watching them for a few more minutes but the behavior seemed to be over and it was quite late so I went to bed. They are both happily moving around the tank today. My question is probably pretty obvious, what is this behavior?

Thanks

[Autumnsky]

That is quite a bunch of snails and snail antics. If you go to applesnail.net you can scroll through and click on any possibly pertinent info. It isn't set up quite as to the point of each item you could be looking for and makes searching a bit difficult. There will be the necessary instructions regarding g sexing snails.

They for sure can practice mating activity and the smaller ones aren't likely to actually be mating yet.

Are you feeding them? They could be really hungry and looking for food.

Are they set up in new or newish tanks?

[WoadRaider]

Originally Posted by Autumnsky

That is quite a bunch of snails and snail antics. If you go to applesnail.net you can scroll through and click on any possibly pertinent info. It isn't set up quite as to the point of each item you could be looking for and makes searching a bit difficult. There will be the necessary instructions regarding g sexing snails.

They for sure can practice mating activity and the smaller ones aren't likely to actually be mating yet.

Are you feeding them? They could be really hungry and looking for food.

Are they set up in new or newish tanks?

I've already been to applesnail.net and a quick perusal of their forum and general information did not avail me of any answers. I did sign up so as soon as my account is approved I'll ask the question there. As for sexing the snails I don't really need help doing that; I, unfortunately, sexed them without knowing!
That's a good point the dime/Nickle size snails in the 10 gallon might not be mature yet so there could still be some males in there that just didn't look good to me.
You can rest assured that I feed (hopefully not overfeed) all of my animals and the tanks are relatively new, already cycled.
Any thoughts as to the throwing/slamming/shaking behavior?

[Autumnsky]

No clue on the slamming around. If they answer, ease let us know! I've had these guys about 12 years and not noticed that ever happening. And why I wondered maybe the one snail had a bit of food and the other was aggressively trying to get it.

I'd check occassionally for any parameter spikes just in case the extra bioloads in the tanks have caused a mini cycle. That can cause fish to behave aggressively. Not sure about the MS.

Maybe someone else here is familiar with this behavior.