Unidentified, erm, dunno!

[pressld2]

Sorry for the less than helpful thread title but I really have no idea where to start with these. I don't even know if they're animal or vegetable, although my guess would be animal.

I'm keeping a tank with some toadpoles and newt larvae in to photograph their development and have noticed a few of these things attaching themselves to the gravel. It looks like they're filter feeding...



To give an idea of size, that's apea-sized piece of gravel it's attached to. It's "stalk" is about the thickness of a human hair and the filaments are very hard to see with the naked eye.

If one of the toadpoles brushes against them they rapidly contract...



To my inexpert eye they look almost like coral...



Any one know what they are?

Dave P.

[bigdave60dog]

Yep, It`s hydra. Dunno what species though.
Dave

[Moonmoth]

Fabulous ! I only thought you got Creatures like that in the sea !

[Ukwildlifeo]

Agreed its a hydra. They are related to Jellyfish and sea anemones and have stinging tentacles (though not dangerous to anything bigger than a water flea I'd have thought). Ive only seen one but they are meant to be quite common. A nice find + photo

[Jim Ford]

Looks like green hydra. We get lots in the pond every year. If you take a jamjar of water with any floating duckweed and let it stand, the hydra can be seen sticking to the sides.

Green hydra have chloroplasts inside, so they're part animal part vegetable.

The bottom image shows the hydra producing a bud, which will develop into a new hydra.

Apparently you can grind up a hydra and the fragments will all develop into individuals.

Jim

[ladyhawk]

Had a google maybe viridissima.

[Jim Ford]

I forgot to mention in my earlier post, that I've also kept brown hydra. The brown hydra will take daphnia and end up looking like lumpy sacks of bricks. The soft parts of the daphnia are digested and the shells later ejected. Plenty of food encouraged budding and you can soon build up a sizeable population. I've made daphnia available to green hydra, but never seen them take anything. I've also never seen them with food inside. It's possible that they have evolved away from carnivory and rely totally on their internal chloroplasts for food.

For such a small creature, they're rather interesting to keep - and low maintenance!

Jim

[pressld2]

Thanks for the replies everyone!

I should hjave known it was a hydra as I do have a vague recollection of them from biology lessons many years ago.

I'll see if I can get some better photos of them later today. The ones I took yesterday I was using a teleconverter with my macro lens and a full set of extension tubes. I'll have a go without the TC today as I think it is softening the images a bit too much.

Dave P.

[pressld2]

These guys are fun!

There's lots of 'em and it looks like at least two different species.

Here's one with a new bud forming...



Here's another with an almost complete child...



I love that one - it looks just like a hand on the end of an arm.

This little crowd are over at the left hand side of the tank which is nearest to the window...



These two are not green and I'm assuming they are a different species...



These are the first ones in the WAB Gallery. It would be great if we could ID them down to species but I suspect that's not going to be possible from photos.

Dave P.

[Jim Ford]

Originally Posted by pressld2

This little crowd are over at the left hand side of the tank which is nearest to the window...

It looks like a couple of them are 'locomoting'. If they don't like where they are, they'll 'walk' themselves to another spot like a geometer moth lava.

I agree, they're great fun. Why don't you put some in a separate small tank and introduce some daphnia to see if they'll feed. As I mentioned earlier, I've not seen green ones feed, but the brown ones do.

Jim