USO (unidentified swimming object)

[TJ]

I just don't get it, the strangest of critters continue turning up in my tanks

This evening, I was surprised to find these fairly large ones swimming around in C.ensicauda tank.

They initially seemed to be shrimp from the way they swam, but upon close inspection that seems not to be the case. I never use live food with this tank so I guess they came in with the plants I added for my gravid females.

Any idea as to what they are and whether they might be trouble?

 

[ira]

i would call those a "supplementary food source"

 

[francesco]

It's a dragonfly larva. Be careful cause they can prey on small newt larvae.

 

[michael]

I once collected a bunch of green water and anacharis from my back yard pond for rainbow fish food. The fish eggs hatched and were doing great. One day I looked in the tank and their were no fish and a bunch of fat damselfly larvae.
Those are either damselfly or dragonfly larvae. I'd hunt them down and get rid of them. The Dragonfly larvae get pretty big. It wouldn't surprise me if the injured a young adult newt.

 

[joseph]

Dragonfly larvae. Dunno what kinda dragonflies live in Japan(prolly some really cool ones) but that little critter kinda resembles the larval darners we have here.If a newt ate it...no problem...but they are vicious predators and, if given the opportunity, will attack quite large food items(larval sallies praps). I've noticed fish seem to be quite cautious and if dragonfly larvae or some other predators are present they tend to keep distance from plants and other thick cover.

Tim: Also, praps to become more invertebrate literate it would be very useful to pick up book on freshwater invertebrates. Soem books deal mainly with microscopic critters however. One that I found useful was Freshwater Invertebrates of North America...doubt that is available over the pond though. It tells about habitat size-food etc. of the animals with plates shown...helps when you are trying to ID an animal or thinking about setting up a culture.

(Message edited by fishkeeper on August 28, 2004)

 

[jeffrey]

I would hunt them out of the tank and release them in some outdoor water source where they are no threat to your dear ones, I once had a natural pond set up and found to my dismay all my minnows and sticklebacks had become food for larvae just like these. Though I have to say I think the adults are beautiful creatures in their own right

 

[joseph]

Not exactly the best idea Jeff...introducing species is much to risky.


If he were mine, I would remove his "mask" and then feed him to one of those C. ensicauda.

 

[edward]

Or you could fish it out of the tank, place it on a large jar with a stick and feed it until it climbs out and molts.
Tim,
Were the plants locally produced or collected?
If so then just let the adults out as many of these species can migrate large distances.
Ed

 

[joseph]

Ed: I've done that before. I have a sequence of photos showing a damselfly pumping ups its wings and then darkening if you are bored enough

 

[edward]

Hi Joseph,
I've also done this (which is why I knew to suggest it).

Ed

 

[jeffrey]

Maybe I should have clarified that I did not mean a natural pond or stream, but took it as read among such knowledgeable folk that I did not mean introducing them to a natural feature.

 

[TJ]

I removed 5-6 of them from the tank and...have been raising them separately

They're now about 2 cm.

 

[jesper]

Those are nasty critters, I looked at some under a microscope a couple of years ago and suddenly I knew where they got the inspiration for the film Alien....
They have long claw-like things(mandibles?) folded under their "chin" that shoots out and catches prey.
Imagine these guys 2m long, ahhhhh!

 

[TJ]

Hmmm, I can't really figure out the anatomy, but she sure ain't pretty...

I've been feeding her bloodworm and Reptomin

(Message edited by TJ on September 25, 2004)

 

[TJ]

 

[shaun]

Awesome - I tried to raise a damselfly larva that I got with some new plants. Sadly, it passed away. I know it isn't caudate related, but I would love to see some progress photos when it begins to morph.

 

[jesper]

Yep the thing that is hanging from its chin there is the folded "claw". Nice shot Tim.
The one I was studying wasn't white, I think it was brownish or black. It was a dragonfly larva, this one doesn't look quite like it.
I challenge you to take a shot of it with its "claw" out tim!

 

[clarence]

Wow! Those are excellent photos.

Bravo! I agree with Jesper. An action-photo of the mandible would be top notch.

 

[joseph]

Not quite an action shot(you would have to have an incredibly fast camera to do that). But here is a picture of a large skimmer dragonfly larvae with the "mask" pulled forward.




Pulled forward

Dental equipment

The same nymph, upside down to show the mask folded back into position

(Message edited by fishkeeper on September 26, 2004)

(Message edited by fishkeeper on September 26, 2004)

 

[clarence]

Wowww...

that is neat!