Hi Jingmei,

It looks like an Oribatida. Most of the species are terrestrial living in the soil-litter, but there are few that are aquatic.They are usually saprophages. It is very interesting that you got it from underground water samples, specially because its clear color (depigmentation?) you may have something interesting there...

Cheers

Jaime Mayoral

Yes ,I think it is because of depigmentation. Maybe this mite fall down in the sample when we pumped and we also found collembola in the sample.your answer is very helpful and Thank you very much

It is definitely an Oribatida. Most likely it got into the sample due to an accident, because I do not think it could possibly live in the sampled environment. Jaime G. Mayoral is right - probably depigmentation. Anyway, it is quite interesting - could you please keep us updated on your further results? Thank you.

Those are two species of oribatid mite species. The upper two show the species from Ceratozetidae family. The lower picture is hard to say because the image is not too sharp. However there are certain groups of oribatid mites which are water-living (Limnozetidae for example). As for the feeding type, you need to know the species to determine the feeding preferences. If you send me the hi-res and possibly high contrast images, I can try identify the species in a day or two. Both species have the normal colour. I do not agree that they are depigmented. Regards, Andrey

I agree with Andrey, these are Oribatida - Brachypilina (most likely). I also know them from water samples from creeks and springs, even pumping samples. The colour seems quite nomal to me, they look like this. Most of them feed on detritus, but to be sure, as Andrey said, I'd wait for his determination.

regards