Moss, Rain, and Rocks: Pond Life Outside the Pond

Desmid Gel on Moss, Mt. Richards.
Desmid Gel on Moss, Mt. Richards.

Not all of water-based life lives in ponds, ditches, and lakes.  In this damp climate, there is water everywhere except in the driest season – within cracks in tree bark, in moss, on rain-drenched leaves, and in the damp of the forest floor.


While hiking around midnight in our constant rain on misty Mount Richards, I noted this gelatinous mass on a dripping mossy rock face:

Desmid Gel. Note water droplets on lower surface of the mass - this is a constantly dripping rock face in winter and spring.
Desmid Gel. Note water droplets on lower surface of the mass – this is a constantly dripping rock face in winter and spring.

I believe that this is the desmid Mesotaenium, which is known to grown on mossy rocks with a constant water supply:

It has been documented in both England and the Netherlands, and consists of dispersed cells in a mucilaginous matrix forming a gelatinous mass among moss stalks. Note that there


Mesotaenium in Gel Matrix, 40X. Note smaller desmid species barely visible in background.

is also a population of smaller algae, likely also desmids, seen at 400X  together with one Mesotaenium cell.

Mesotanenium and Smaller Desmid Species.
Mesotanenium and Smaller Desmid Species.

Images of the larger desmid species show shape and chloroplast structure typical of Mestaerium:

Mesotaenium, 400X. Note chloroplast structure and surrounding cell wall.

In some images, the refractile mucilaginous sheath surrounding individual clusters of desmid cells is visible:


This is a link to an older but informative article discussing mucilaginous algae as well as 1980s theorizing about diatom movement – 1980s knowledge and one of the more pompous and verbose articles in the literature (“…palmelloid cell masses of coccolithophorids…”), but also very infomative:


Note on pages 120-122 the comments on the significant role played by mucilaginous gels in Mesotaenium and other algae:BONEY MUCILAGE 01

as well as the potential size of some of these sheets of algal gel habitats:


Nice result from my mountainous wanderings with a headlamp at midnight in the cloud layer.


If you explore all possible things that are common and unnoticed, the world will never a boring place.

I have one old car –  a beloved 1993 Mercury Topaz bought for a dollar from my uncle’s estate, 22 years old and with only 60,000 miles on the odometer.   From the era when Detroit thought it could build cars from rubber bands and old sardine tins, it is grossly underpowered, occasionally blows a tired old engine seal, and has a back window that repeatedly leaks – yet it has proven to be a faithful and undemanding servant.  After a few months of continuous rain, its rubber window seals turn green with a film of algae.

This note is for Kelly Averill Savino, to answer your question regarding my picture of ugly little desmid blobs in a pot.
The implication behind your question was “Whatizzit? What desmid mass? Surely not those ugly little blobs that you can barely see??? Wipe them off with a Kleenex, PLEASE!”
That’s the point. Desmids (see Wim’s lovely images: are some of the most beautiful objects that you can see under the microscope. However, in their appearance in nature, they can take the prize in the category of “ugly-little-masses-that-only-a-mother-could-love.”
The point of my post on Triple Tree (and one of the least appealing pictures ever posted on this site) is that they are easily missed and not very appealing when you find them.
Gel formation and mucilaginous coatings are very important for algae, and some desmids seem to take this to the extreme. I find them on midnight rainy mountain walks, forming ugly little snotty blobs on shaded, drippy rock faces. Or, as in the last note, forming equally ugly, snotty little blobs in an overwatered nursery pot.
However, under the microscope, these nasty little blobs form an amazing and complex little world. The one in the images, formed on lichen on a drippy rock face, contained gels within a gel – a mucilaginous blob, containing multiple tiny gel spheres of higher refractive index (looking rather like a tapioca pudding at low magnification), each containing its tiny cluster of bright green desmid cells.
This gelatinous little world also hosted other organisms, in this case a tiny nematode and a branching black mold.
The Boney article, though dated and verbose, contains much thought-provoking information on algal mucins:
There is much interest in algal mucins in the health and biotech field because they apparently have medicinal and nutritional properties:
Moss, Rain, and Rocks: Pond Life Outside the Pond

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