[Scuttie]

So recently I had a very strange cherry shrimp death in my 5.5 gal tank. I'm not sure how this could have happened, but this morning I found the shrimp with its head severed from its body. The only other creatures in the tank include espei rasboras, a young male lyretail guppy, other dwarf shrimp, and a young bamboo shrimp. As none of these species are aggressive towards shrimp, nor have I ever witnessed any signs of aggression, I'm really confused as to how this could have happened. Anyone got any ideas? The tank is moderately to heavily planted with a good number of hiding spots and I do a 40% water change every 2 days. The temp is 75 - 80 F and at most, nitrates get to 10 ppm before the water change.