Chaetonotus bisacer is described in the literature (Schwank, 1990) as a globally distributed gastrotrich, which has already been detected on various continents. However, the species seems to be extremely rare at my sampling sites. So far, I have only found 2 specimens in April 2026 in Ulmisried. There, the specimens were found in decayed sludge from decomposed leaves.

The most characteristic feature of Chaetonotus bisacer is a straight, transverse row of long spines, which runs approximately in the middle of the dorsal side. These spines are straight and have a double tip at the distal end. In my specimens, these spines were between 38–44 µm long (s. figs. 2, 6 and 7).

The scales on the dorsal side have a fairly homogeneous shape. They are shield-shaped, keeled, and have a notch at the distal end. In the middle of the body, they were about 11 µm long in my specimens (s. fig. 7). On the ventral side, there are narrow, keeled scales with a length of 5–6 µm (s. figs. 10 b and 11 b).

In freely swimming specimens, two long spines can be seen at the posterior end (s. figs. 10 a-b). These are the primary lateral spines, which extend far beyond the toes. Slightly above them is another pair of secondary, lateral spines, which are, however, much shorter (s. fig. 9). Between the toes, the body appears transversely truncated.