# Nemertean Hunting Behavior



## SnakePaparazzi (Jul 20, 2008)

Has anyone ever watched how nemerteans hunt? I was fortunate enough to watch this happening this weekend... If only I had a video camera on me at the time...

So there I was, doing my usual observation of the feeding behaviors of my frogs...

I was looking into my standard intermedius tank trying to locate all of them and watch them each devour a few tasty fruit flies... 

During my observation, I noticed a decent sized nemertean (approximately 3/4 inch) climbing the stem of a begonia like a python would a tree... I also noticed a fruit fly wiping off the supplements that he had bathed in just moments before so my attention was now averted to him...

All of a sudden, the nemertean thrusts it's "harpoon" at the fly with deadly accuracy, snaring it... It then proceeded to the other side of the begonia stem, out of sight...

Has anyone else ever witnessed anything like this? I knew nemerteans were capable of wiping out springtail and other microfauna populations; but I had no idea they were capable of taking down a fruit fly...

-Christian


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## punctata (Jan 31, 2011)

In my tricolor tank I see them on my glass in the morning but I remove them and kill them. I do not get to see them hunt


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## SnakePaparazzi (Jul 20, 2008)

I am tempted to set up a mason jar and put a few nemerteans in there and watch/film them hunting fruit flies...

-Christian


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## Ed (Sep 19, 2004)

There are older discussions on here where people discussed the predation on fruit flies. They utilze a venom along with digestive secretions to subdue prey larger than themselves. 

Ed


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## SnakePaparazzi (Jul 20, 2008)

I never realized how fascinating these pests could be! Thanks! I'll definitely be looking up videos!

-Christian


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## frogface (Feb 20, 2010)

I had the unfortunate opportunity to watch them hunt. I watched them stalk and eat bean beetles and flies. Pretty neat if it didn't piss me off so much


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## c81kennedy (Dec 24, 2010)

My thumbnail froglets are the size of bean beetles should I be worried?


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## Erikb3113 (Oct 1, 2008)

It is crazy, they seem to know the feeding schedule as well as the frogs. The ones in my tanks camp out above where i deposit flies. I've usually seen them hunt with more of a whipping, sweeping attack. To the previous post, I've never heard of them taking down frogs. That would be very disturbing.


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## yerbamate (Nov 3, 2013)

Has anyone ever seen frogs eating nemerteans. Seems like they would be a tasty treat, unless they have some offensive aftertaste like millipedes..


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## Cuthbert (Mar 30, 2011)

yerbamate said:


> Has anyone ever seen frogs eating nemerteans. Seems like they would be a tasty treat, unless they have some offensive aftertaste like millipedes..


I've seen my young luecs eating tiny nemerteans (I'm next to positive they're nemerteans--head waving, having a proboscis). And I think I've seen my Iquitos froglets eating them. I can't remember if this is normal behavior for pdfs.


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## Umbra (Nov 29, 2013)

Cuthbert said:


> I've seen my young luecs eating tiny nemerteans (I'm next to positive they're nemerteans--head waving, having a proboscis). And I think I've seen my Iquitos froglets eating them. I can't remember if this is normal behavior for pdfs.


I'd bet those are _Rhynchodemidae_ flatworms. Nemerteans move like slugs and don't do the head waving thing. The "proboscis" you're seeing is likely just the anterior end of the worm. A nemertean proboscis, when fired out, is much longer than the worm itself. Here's an example:










I don't see why it wouldn't be normal behavior for pdfs, frogs on a whole are opportunistic predators of smaller animals that they perceive they can tackle. If there were mice the size of fruit flies, I'd bet pdfs would eat those just as their larger relatives will consume. Most keepers probably don't see it happening because once they see the worms, they might feed far more often/larger quantities out of fear of the worms out competing the frogs. Prey preference likely plays a role here - springtails and flies are likely relished over the worms. Also like most animals, frogs probably have varying individual preferences as well. I'd bet if most owners were to observe closely after dark, they'd probably notice their frogs taking shots at any really tiny worms they come across. 

To add to this, baby flatworms/nemerteans are probably spending most of their time actually in the substrate feeding on the tiniest of microorganisms (baby springtails would be my bet) while the larger specimens spend more time crawling around the surface hunting more substantial prey so juvenile worms are probably a much less frequent encounter than larger worms.


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