We found something pretty cool while assaying a client’s soil this past week, so naturally we want to share.
Unfortunately, it’s not really so cool that we found this microbe. It’s a root-feeding nematode, a thing that can kill entire crops. They thrive in poor soils (although this soil wasn’t especially poor), and are generally bad. We don’t like to see them.
But this ‘tode was sure fun to look at! Being large and slow-moving, it was both fascinating and quite easy to observe and photograph.
The two distinct features that positively identify a root-feeder are the needle-shaped object just back from the mouth, and the knobs at the rear of said needle. The knobs are muscles that the nematode needs for shoving its needle through the hard surface of a plant root. By so puncturing the root, the nematode can feed on its interior.
A fungal-feeding nematode would have a similar morphology, but without the knobs. Finding one, moreover, is always good news. What’s especially cool with our foot-feeder is how distinctly both knobs show up, even in the photograph (image-quality-wise, photos never equal direct observation).
This specimen showed up in initial assessments of an outdoor horticultural bed, and we’re still not quite sure why it was there. Testing has yet to turn up any further signs of low-oxygen conditions, beyond a few oomycetes (anaerobic fungi, which can often appear in decent soil).
The bed showed signs of heavy bacterial dominance, with thistles and a running grass having overtaken the surface during its several years in cultivation. It has been covered with cardboard and woodchips since last autumn, and there appears no discernible compaction.
There do exist, however, nematodes that can adapt. With their ability to straddle the boundary between aerobic and anaerobic conditions, they fall into a class known as facultative anaerobes. We figure it is possible that this nematode may feed on roots in low-oxygen conditions (when plants are weaker, and less able to fend off infestation), and switch to grazing on fungus in higher-oxygen conditions.
Anyway – we’ll keep poking around and see what turns up. Until then, thanks for geeking out with us!