What are these slug looking things in my garden pond?

May 19, 2016 9:25 AM

And why are they dead? Pic. Pic. Pic. I live in Minnesota.

Are they just slugs? Why are they in my freshwater pond? Why are they dying there?

This is my first spring with this ~180 gallon pond/waterfall and I'm trying to learn the ecosystem a little. This is a gross part of the ecosystem that I would like to unlearn/learn how to make stop.

Will something eat them (we have some wildlife around here, including the occasional pair of ducks)? Or should I pick them out so they won't just rot in the water?

posted by sparklemotion to Home & Garden (7 answers total)

Yeah, those look like regular slugs to me.
posted by ArgentCorvid at 9:39 AM on May 19, 2016

Regular slugs. Don't know why they're dead but I wouldn't be alarmed about that part. Yes, they'll get eaten by something sooner or later. I'm not sure that most slug-eating wildlife such as birds will eat dead slugs but there's all kinds of smaller things that will be happy to eat them as they decompose. If you have fish in the pond they will definitely be happy to eat the corpses as they start to disintegrate--fish are generally not picky about that kind of stuff.
posted by drlith at 10:28 AM on May 19, 2016

Conjecture here, but might they have frozen/gotten too cold? We've had a spate of colder than normal temps this May, following a pretty warm April in Wisconsin/Illinois - I'm guessing you probably have too.
posted by sarajane at 12:18 PM on May 19, 2016

They may have crawled into the pond and/or somehow been washed into it-- once in, they would drown, which is why they're dead. They can't really swim or anything, and may not be able to even crawl out in time if the sides are slick or whatever. If there are plants around the waterfall area, that may be the source-- slugs crawl out, head towards damp waterfall area, get caught up by waterfall current, washed into deep part of pond, drown.
posted by The otter lady at 12:44 PM on May 19, 2016

Yes, it has been freezing or close to it the past several nights here in MN.

I am guessing that they are always there, but they usually aren't dead (it normally doesn't freeze nightly this late into May), so they bury themselves or get eaten by predators that prefer them alive before you see them.
posted by TinWhistle at 1:25 PM on May 19, 2016 [1 favorite]

They look like plain old garden variety dead slugs. Decomposition is a natural part of any ecosystem, so there's no reason to remove decomposing things. If they don't get eaten by a larger organism, the fungi and bacteria will break them down.
posted by hydropsyche at 3:35 AM on May 20, 2016

I have the same issue with snails. I suspect they're attracted to moisture but they're both not really smart enough to anticipate drowning. My rain barrel (which is almost totally sealed) always has a handful of dead snails in it as does my watering can if I leave water in it. I think they don't die instantly, it takes some time for them to stop once they're in the pond.
posted by GuyZero at 7:58 AM on May 20, 2016