Snail Guessing-Games!

[Vale!]

I believe this is called "Infotainment"!

I've been looking at Malaysian Trumpet Snails (MTS) recently, the reason for which will unfold itself below, eventually ..

Guess #1

I acquired a couple of MTS a few weeks ago, sourced externally to Vale! Towers. Meet Linda ...



... and Leslie (she's next to the temperature sensor):



At least one of them is a lady snail but since there are few males in any given population of them, for present purposes I'll assume that both are. I put them in with my Moina (Daphnia-type critters) exactly a month ago. They've been producing some baby snails, as I'd hoped. Question One is: how many babies have they produced?

I don't myself yet know, btw - I'm going to count and remove them tomorrow. An MTS female can carry an astonishing number of babies in her brood pouch, at various stages of development presumably. But I don't know how long each is in there before they march out to explore the world or how many may exit at a time. On the other hand they haven't had an awful lot to eat - just whatever Moina food has managed to settle on the glass before being munched. There's a heater in the tank (26C) which might also influence guesses, I guess. I grabbed a pic of a new-born:




Guess #2

The presence of Linda & Leslie stems from last Summer/Autumn when I had decided to convert a fishy tank (Sheba 4) into an invertebrate tank. For the previous couple or three years it had a bunch of Corydoras in residence. The substrate was sand that itself hosted a healthy population of MTS.

This pic was taken soon after I'd cleared everything but the substrate. It's very mucky because I'd not long before squeeze-rinsed all the filter sponges in the main tank (in normal operation the sand had been perhaps surprisingly clean) :



But you can probably make out a delegation of snails. I collected them by syphoning out through a kitchen strainer. I couldn't tell what proportion of the snaily population I'd trapped ; I thought it might be quite high, given the tiny reticule of the strainer. Now, because of what's described vis-a-vis Question #1 I've seen the size of the newly-born and am confident that I got pretty much all of them. Here they are:





So your Question #2 is: how many snails did I catch?

This operation had followed my multiple attempts to eliminate them using eSHa's 'Gastropex'. It hadn't worked so I had contacted eSHa to try to understand why. In theory the resulting conversation is still going, but I can't help feeling that it's actually fizzled out! I thought it might have something to do with the very soft water and/or its acidity.

One of eSHa's observations (they'd been sent the same photo as you've just seen) was that, given that MTS are 'big snails' (their description) there was just too much snaily biomass in the tank for a standard dose to be effective. In fact, as I was able to point out: although MTS in optimum conditions may grow to be the best part of a couple of inches long, in Sheba 4 they got nowhere near that. I'm not sure they got anywhere near their normal max lifespan (between 1 and 2 years) either. Here are the biggest three that I could find (pictured after everyone had dried out for a month or so):



They don't really represent the prime of snailhood. What with the water conditions and with Corys shoving them around it's not surprising, I suppose!

Another snippet vouchsafed by eSHa is that the microblighters (chiefly bacteria) that may build up over time in the substrate also absorb some of the effectiveness of Gastropex. There was leaf-litter in the tank which wasn't removed/renewed very often, so that's probably a contributor. They were asking me about the size/type of the tank's filters, too ; I wondered whether that was because filter microblighters act in the same way ... I'm still awaiting confirmation or otherwise of that. Anyway a damn good hoovering (and possibly a filter service) before starting a course of Gastropex seems to be indicated!


Guess #3

When the snails had thoroughly dried out, and merely from curiosity, I roughly measured their total volume and weighed them. You have your estimate of the number of snails and you have a vague idea of their size, so:

Guess 3a : Loosely-packed into a small measuring tub, what was the total volume of snail shells?

Guess 3b : What was the weight of the above?


I'll leave those with you for a few days and then post the numbers. I may in the interim consider questions. I can think of one right away, actually, but the Call Of The Guinness unfortunately trumps making the edit to insert the relevant info above!

[plankton]

I've always thought MTS were hermaphrodite, not male and female (well, technically both I suppose )?
None of my MTS have ever got to rabbit or elephant snail size (over an inch)....and they (rabbit and elephant) do have males and females as do assassins.....or have I just got completely senile about aquatic snail reproduction?

[Stephen]

I tried eSHa's Gastropex when I had a load of MTS in my tank (going back a few years ago).
It forced many MTS up the glass and I manually pick them out and got rid of them. There were hundreds and probably hundreds more that I couldn't see.
The only real way to get rid of snails is to empty the aqaurium, give it a clean and start again (which I done).

I've always thought MTS were hermaphrodite, not male and female (well, technically both I suppose )?

Malaysian Trumpet Snails are a live-bearing species that can reproduce in two ways: either through parthenogenesis or sexual reproduction.
Parthenogenesis is where females give birth to young female clones. These will be genetically identical to the parent. Males are not needed to fertilize the eggs for this to happen.

[Stephen]

So your Question #2 is: how many snails did I catch?

Guess #3

When the snails had thoroughly dried out, and merely from curiosity, I roughly measured their total volume and weighed them. You have your estimate of the number of snails and you have a vague idea of their size, so:

Guess 3a : Loosely-packed into a small measuring tub, what was the total volume of snail shells?

Guess 3b : What was the weight of the above?


I'll leave those with you for a few days and then post the numbers. I may in the interim consider questions. I can think of one right away, actually, but the Call Of The Guinness unfortunately trumps making the edit to insert the relevant info above!

Guess 3a : Loosely-packed into a small measuring tub, what was the total volume of snail shells?
My guess approx 500 shells, volume half litre

Guess 3b : What was the weight of the above?
My guess 4oz (113 grams)

[Vale!]

It's time to put you all out of your mystery!

First though I'll expand the 'shorthand' statement I made regarding the collection of the snails from Sheba 4 ...

The kitchen sieve had a reticule of about 0.8mm (so far as I could measure it). I had scooped the sand bit-by-bit into the sieve and shoogled it in a bucket of water. The sand fell through, leaving the snails in the sieve - along with bits of botanical detritus which later I tweezered out (once dry). I then relocated the sieve to the outside drain and syphoned out through it any snails remaining in-tank, together with all the water. To encourage the tank to be MTS-free, I then painted all surfaces with 6% hydrogen peroxide. The filter sponge had been put in a bucket of water and scanned every day for any snails poking their noses out (there were very few - maybe a dozen in total) until I found none for three days.

I'm looking at my reply to one of eSHa's questions back in December and I see that I dried the snails for just over two months, rather than one as I'd suggested, before counting and weighing. My estimate of the volume of sand in the tank was 8.86 litres, btw. Anyway, back to the quiz ...

Guess #1 : How many babies had Linda and Leslie produced in the Moina tank during thirty-one days? They together (assuming both female) had produced 166 babies : about 5 per day (5.35 to be precise). Stand by for the results of a further exercise at the end of this post!

Guess #2 : How many snails did I capture from Sheba 4? I estimated this after they had dried out: I shuffled them and weighed out 10% which I counted. I did this twice, took an average and multiplied it by 10. Through this method I estimated 670 snails.

Guess #3a : Poured into a measuring cup and tapped a few times to settle them, the total volume of the snail population in Sheba 4 was approximately 28 millilitres. That's not a typo!

Guess #3b : The shells (plus the desiccated bodies inside them, I suppose) weighed 8.43 grams in total.


Brucie Bonus!!

In resetting the little Moina tank [see Guess #1] I removed Leslie, leaving Linda as the sole snaily occupant. Yesterday I stripped the tank again and counted the number of babies that Linda had produced during the intervening six days. This pic shows 24 of the first 25 that I found (one vanished while I was arranging the camera!) ...



I subsequently discovered five more lurking on the inner surfaces of the heater guard, so the overall total was 30. That's 5 per day, close enough for jazz to the 5.35 per day that Linda and Leslie had produced together. I've now read that male and female MTS have differently-coloured genitals - one's red and one's green I think ; I've assured them both that I won't be expecting them to suffer the indignity of inspection. So Leslie could be male, or lazy, or both! Mind you s/he was appreciably smaller than Linda, so perhaps not fully trained up yet if female!

This I thought was the smallest baby that I could see:




I've deliberately included in that pic my latest superweapon against (in particular) small-to-medium sized pond snails. I like a few snails around but pick out some on an ad hoc basis, to try to prevent excess excess (if you see what I mean). The most difficult to remove are those who crawl up the glass, especially if short thumbnails and/or chubby fingers are involved! Unless their shells are somehow gripped, they let go and fall to the floor.

After having gone through multiple search strings, I discovered and bought a pair of tweezers with cupped prongs! Something to do with body piercing, seemingly. It's not a perfect weapon, not least in that the 'edges' of the cups should ideally be thinner, but it's a significant improvement. And if snails do fall then it's possible to scoop them up immediately while avoiding dredging up an unwelcomely large pinch of gravel with them! If there are dedicated snail-grabbing tongs out there, I haven't come across them, have you? I can think of other tweaks to the tweezers I have that would be game-changing ...



Anybody know the phone number for Dragon's Den?

[fr499y]

techincally there are 'Escargot Tongs' out there, but aren't very useful in this scenario!

I just use a pair of fine tipped planting tweezers

[Si4geckos]

But how many MTS are in this bush?
LEVEL: Hard

[Martinspuddle]

But how many MTS are in this bush?
LEVEL: Hard

Answer: ...more than one!

[Chris_jennings]

Martin Ill raise you, at least 2

[Si4geckos]

But how many MTS are in this bush?
LEVEL: Hard

Answer: ...more than one!

Close. It was actually more than 3...