Hydra viridissima

[Grahame]

Hi folks,
These are growing on the inside of one of my freshwater jars.
They are only a few mm long and expand and contract on stalks with a holdfast on the jars surface.
A week ago they were quite pale, I guess they are filtering algae to turn them green.
Some now are growing new branches as seen in image 1, it has two new branches growing.
I'm sure I've seen similar in this part of the forum before but suspect it was many pages back.
Any ideas folks ?
Thanks

[MichaelG.]

Very nice images, Grahame

https://en.wikipedia.org/wiki/Hydra_viridissima

MichaelG.

[Grahame]

Thanks a lot for that Michael
Another something new learnt.
I changed the post subject to the name.
Hopefully aceptable on this board ?

[mrsonchus]

Really nice image grahame - not my area at all but I see lots of morphological detail to explore.
Interesting to find an ID to species level also.
Interesting that it's perhaps less predatory than other Hydra species, presumably on account of the supplemented energy-source that is the algae within. Also perhaps follows that it may have relatively shorter 'arms' as a consequence.
Form/function relationships are always a fascination to me, the sheer logic astounds me, even when it's an animal rather than a plant!

Thanks for the interesting post and MichaelG's ID.

John B.

[billbillt]

Thanks a lot for that Michael
Another something new learnt.
I changed the post subject to the name.
Hopefully aceptable on this board ?

Certainly it is acceptable to this board!... Things are not that stringent here..

Regards,
BillT