what would cause this in nematodes?

[Lilly Begonia]

I've seen several examples of this in the last half hour, nematodes with a severe kink in the middle of them, and I'm wondering if there's something in their environment that might cause that. Perhaps they have exhausted certain nutrients they need in the petri dish?



Here's one that seems to have ruptured mid-section.

[actinophrys]

These look a lot like injuries from some attack. Since they are so common in your samples I am inclined to say tardigrades, which feed by piercing, some as herbivores and some as carnivores. Nematodes can definitely be prey; I couldn't find much detail, but some photos of attacks here and here, and a video here, make it seem plausible this is their work. With luck maybe you could catch one in the act.

[Lilly Begonia]

These look a lot like injuries from some attack. Since they are so common in your samples I am inclined to say tardigrades, which feed by piercing, some as herbivores and some as carnivores. Nematodes can definitely be prey; I couldn't find much detail, but some photos of attacks here and here, and a video here, make it seem plausible this is their work. With luck maybe you could catch one in the act.

Ah! I had thought perhaps predation! I would certainly like to catch that in action! I've seen a great many nematodes, but until today none affected like this. On the other hand I've seen a great many tardigrades in my samples. Very possible that's what's going on.

[Jonnyvine]

Nice