Swimming snail?!?

[BigRedSpecial]

Last night something caught my eye; it was a tiny snail, the same size and round shape as a Colonista (which I have a lot of), but whereas all the colonistas in my tank are white and burgandy, this guy was beige(both shell and foot), with two visible black eyes.


Now what really caught my attention, is then he started swimming... not floating like a freshwater Apple snail, but using his foot to propel himself through the water, using a 'twirling' motion.

He stared in the water column for a minute or so, then stuck on the glass and continued grazing.

Any idea what it could be? my LR is a mixture of Fiji, marshal islands and some Tonga.

 

[charlesr1958]

I wouldn't know the species or the number of species that swim but have seen it myself and was told it is quite common for any number of snails to do so.

Chuck

 

[pagojoe]

As Charles says, there are a few different families of gastropods that may swim. Charles has seen the scissurellids do it, and I've seen a few species of trochids do it. Apparently, both swim by twirling the foot and zooming around like a helicopter. Yours could be in either of the above families, although there may be other related families that show similar behavior. All are algae grazers, as far as I know. I've seen trochids in the genera Monilea and Ethminolia swimming just like you've described. Some of them look very similar to Collonista snails, but they have a transparent amber disc for an operculum rather than the Turbo type operculum (hard, shelly material) found on the Collonistas.

When this was discussed a few years ago, it was apparent that a lot of the shell people as well as the aquarium people had no idea that some gastropods swim like yours did. I don't think too many people have witnessed it.

Cheers,


Don

 

[BigRedSpecial]

Thanks guys, nice to know I wasn't experiencing something no one would believe!

Pagojoe, The swimming was exactly as you described, but I couldn't see the operculum. I'm going to google the species you've listed to see if I can make an ID.

It's cool to hear few people have seen it though, makes me feel special!

Thanks again

 

[BigRedSpecial]

After a quick google search, the closest match I could find was Ethminolia stearnsi, according to pictures. I couldn't find and info on size though.