Sexing Japanese Trapdoors (Viviparus malleatus)

[Flaringshutter]

It's nearly impossible to find any information about sexing these snails on the internet. A while back, when I bought my first little viv, I dug around in some scientific articles (because I'm kind of a science nerd) and discovered that the best information available says that males should have a shorter, blunter, curled right tentacle. Females should have two straight tentacles of even length.
This is because males don't have a true penis like apple snails; rather, their tentacle is a modified sex organ.
There is mention of this in a few scientific articles relating to Viviparus species:

The males of Viviparus are easily recognized by their enlarged right tentacle, which is used as a copulatory organ (Fretter and Graham, 1962).

From the article sample found here: http://www.jstor.org/pss/1938778

The only external feature that we found to distinguish sex was the modified (blunter, shorter, and thicker) right tentacle of the adult male (fig. 2). This organ is similarly modified in both the juvenile and adult V. contectoides (Van Cleave and Lederer, 1932), but in the juvenile Japanese snail we found no such dissimilarity."

from p 34 of this article: https://kb.osu.edu/dspace/bitstream/1811/5359/1/V68N01_032.pdf

Reproduction was semelparous. Females brooded a single batch of eggs for nine months during their third year (27-36 months old), released the young in April, and died at 38 months of age.

From the abstract for the article found here:
http://www.jstor.org/pss/1467137

So very interesting stuff, lifespan of 2-3 years in the wild, 9-month gestation just like humans.

Anyway, just the other day I picked up a few more of the same species and was able to clearly see the distinction. Both sexes were out and about today so I snapped a couple shots.

Male - notice the shorter, curled tentacle:

Female - both tentacles are straight and even length:

Since these snails are livebearers and extremely slow growing, it's not such a big deal to know the sexes. However, I like to name my snails and it's convenient to know which is Samuel and which is Samantha.

 

[petluvr]

Nice snails, I was thinking that the next tank I set up I may put some of these in.

 

[vampie]

I like these snails, they look like little elephants. Their babies don't seem to survive in my tanks though.

 

[thebullit]

i have a breeding pair of these. a couple of days after getting them she started to give birth, and had about 15 babies. they have mated since so i will have to wait 9 months...

 

[msjinkzd]

Wow, great info!! Thanks! They are so cute

 

[fishorama]

Very interesting & attractive snails. Thanks for sharing all your research.

 

[Inka4040]

Thanks Flaringshutter! I've got some of these coming in the mail, so this came at a very opportune time! Sweet looking snails!

 

[Flaringshutter]

Glad you all found it useful! One of my favorite things about keeping aquariums is looking into all the scientific articles online that relate to certain species or diseases but that aren't usually applied. Lots of good info. Yea, I know, that makes me a science nerd...

Anyway, I think the vivs are some of my favorite snails so far. They're just so darn cute. Too bad they're so shy. I would love to hold them.

 

[Camp]

Thank you for the info.
I have a few of these right now, and really enjoy them!
They remind me an awful lot of octopuses.
Thank you for sharing!

 

[SnailsTales]

If i take some pics of my large snail, can u identify them. I',m new to this and mama just had 12 babies!