MicrobeHunter.com Microscopy Forum

A friend gave me a sample of moss from her garden a few days ago. I put the moss in to a Tupperware container (without the lid) and looked at some of the water under the microscope and all I could see was a nematode. Now, after the sample has been soaking for four days I took a drop of the water and now it’s full of life. I can see what I think is bacteria but what grabs my attention is these balls. They are hard to see in the video but under the microscope I could just make out what looks like flagella on these balls. I have no idea what they are but they can move fast when they want to.

Dear MicroPunter,

beautiful pictures! As to the subject of your query, I have been seeing them fairly often, usually in samples of garden water, near moss and decaying leaves. They are biflagellates, green algae, from the Volvocaceae family (aka globe algae). They are truly ubiquitous. Firstly observed by van Leeuwenhoek in 1700, who just like us really liked their appearance, calling them 'a very pleasant sight'. Both van Leeuwenhoek and Linnaeus wrongly considered them animals. The green spheres inside the big 'ball' are maturing daughter colonies, with their flagella turned 'inwards'. Once released from the mother colony, they flip 'inside-out' to begin using their flagella. The outside layer of the big sphere are individual algae. The movement you mentioned in your post is sometimes referred to as 'roll and spin', they are equipped with thousands of flagella on the exterior layer of the colony. If you are still interested in some extra reading about Volvox/Volvocaceae, I would recommend 'Origins of multicellular complexity: Volvox and the volvocine algae' by Matthew D. Herron (it is a free open-access paper, doi: 10.1111/mec.13551).

Wishing you happy observations,

Dom, nanomedic