Euplotes from the North Sea

[janvangastel]

Today I went to the IJmuiden pier (about 30 kilometers NW of Amsterdam) and took a water sample with some algae at the border of the North Sea. One ciliate I already found in my first specimen is this ciliate, I think an Euplotes species. I could not find an identification key for marine ciliates, maybe someone can point me to such a key. It looks like it has eaten eye flagellates, because I can see red dots inside the green algae.

[Hobbyst46]

Very clear and beautiful images.

[Wes]

Very nice find, thanks for posting!

[Bruce Taylor]

I could not find an identification key for marine ciliates, maybe someone can point me to such a key.

For ciliates found in sediments near the shore, I'd recommend Philip G. Carey's Marine Interstitial Ciliates: An Illustrated Key: https://www.springer.com/gp/book/9780412406102 It doesn't cover pelagic or planktonic ciliates, and is very expensive, but very useful if you can find it.

A handy compilation of recent articles on marine ciliates from China: https://www.springer.com/gp/book/9789811359002

Colin R. Curds included marine species of Euplotes in his guide to the genus, from 1975: https://www.biodiversitylibrary.org/part/33538#/summary

The algae in your Euplotes look, to me, like endosymbionts. There is no sign of digestion, very little variation in size or colour, no sign of food vacuoles.

[janvangastel]

Thank you for the links Bruce. You are of course right about the algae.

[Rapidray]

Sharp and clear video.