Great Ramshorn / Posthoernchen / Planorbarius corneus

With a green moss dress / In einem gruenen Kleidchen aus Moos



4 comments so far...

Fizgig December 06, 2021, 06:25 PM
I have some of its relatives in my aquariums =) Nice find! Too bad it doesn't have any friends to clean the algae off its shell...
Sonja December 16, 2021, 09:33 AM
There are many pond snails in the smal standing waters and lazy fkow zones built for renaturation here in summer, but ramshorns are very rare finds, and usually the people from nature centres are not even exited if you report one but just say: "Damned idiot aquarium owners, I bet there are a few new goldfish in there too, then!" or somesuch. ;o)
But I love ramshorns., they look almost like living ammonites, sooo cute....
Fizgig December 16, 2021, 06:37 PM
The joke's on the person who told you these were introduced -- they are native to Europe. These snails are a decent size, voracious, and prolific, but they are also short-lived & breath air and, it turns out, don't perform that well in very polluted waters (aquariums included) -- not to mention that most fish love to eat snails. The poor water quality likely accounts for their rarity in that body of water -- being air breathers means they need a healthy, established ecosystem to thrive. Not likely introduced by aquarium owners as these snails are rare in the trade and not as useful as their smaller cousins (which don't eat live plants at all) so hobbyist generally steer clear of them (one doesn't add useless bio-load into an aquarium or if they do, they don't do so with snails). Being a "natural restoration" project area, it's more likely that one of their own added snails. Unlike fish, unwanted aquarium snails are easy to dispose of (using copper), so no aquarium owner is going to go through the trouble of removing them manually and every aquarium owner knows that removing the visible snails doesn't take care of the over-population problem since this species is an egg layer. Besides, it's exceedingly rare for this species of snail to overpopulate as they breed in response to available food source. So, I think they're wrong in blaming this one on aquarium hobbyists -- especially for a native species ;) The Goldfish, maybe -- though, who hasn't seen a bird drop a catch? Yeah, people release fish, but they don't usually go all out of their way to some middle of nowhere pond --- the local lakes are usually their dumping grounds ;)

If you love ramshorns, you'd really like the small aquarium hobby ones --- they come in a wide range of colors and rarely get bigger than a small marble. I have brown, copper, red, blue, leopard, and opal colored ones in my aquariums =) Interestingly, it's the body color of the snail seen through an opaque shell that gives these snails their color -- unlike their larger cousins, like the one pictured, whose shells have color ;) Fascinating critters.

Sonja December 23, 2021, 11:05 AM
I don't think it was meant like it would be not native. It is just their oppinion that most obseved in easy accessible manmade ponds are captive born animals once sold at the aquaistic shop and thrown out along with other unwanted waterpets.
I guess it is because the poor mystery ramshorn did not come from a source they controlled, like the euripean pond turtles. An Emys observed again after release is exiting, a ramshorn is not. Thats beause they did release turtles themselves but no ramshorns. If it should be really wild, that would be of course very exiting, but how to prove that rather than to err on the side of caution? ;o)

BTW the ponds of the Swabian Heimatbund nature centre at Willhelmsdorf are hardly the middle of nowhere, it is basically a hatchery ruin made into a nature exhibit with tiny naturalized bodies of water flowing into each other just outside a smaltown and next to the former peat company turned a sizable wild NSG. Access is all free unless you go inside the buildings to look at the exhibits indoors and use the facilities. Many families go there during holidays, some childens groups with teachers get tours on workdays and otherwise it's a site for birder and hobby enomologists worthwhile to check. Walking dogs and jogging inside the ponds maze just for the soft paths is dicouraged but enforcement lacks somewhat. It's peaty there with some reddish water, but I would guess comperably cleanly. The bog is the source of two rivers, but has no river flow into, so there cant be much pollution upstream as peat farming stopped decades ago.
It was the second ramshorn I spotted in a water body in this area of the Pfrunger Ried within 14 years or so. The first report sat not so well with the person manning the exhibit that day long ago, so this time I did not report it. BTW the first ramshorn I met there was green and fuzzy as well, but so was the poor lone and shortlived ramshorn in the aquarium of the asia takeout too. I have seen clean ones in many colours just as you describe, but usually at zoos and of course at the big garden centers which sell aquaristic stuff.. I thought most water snails simply will aquire a hairdo when population density is low and they might need always a friend or several of the own species to eat their shell free of greens. After all they cant lick the own deriere like a cat..... ;o)

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