About one of the darkest clouds I learned in Bork at the conference on the behavior of aquatic invertebrates (medical leech - the most that neither is an invertebrate creature, because without a single bone).
Now, in one of the laboratories of the Institute of biology of inland waters watched the changes and the behavior of leeches, when the water fell chemical dirt, unfortunately now a normal washing powder Lotus, pesticides, phenol... In the water with an admixture of "Lotus" leech first rushes, and then nothing falls to the bottom.
The chemical chlorophos insidious differently: first, the muscles leeches are compressed, then relax, and invertebrate creature gulps water. Alas, too late. And that's what is especially sad is a feeling in the water impurity washing powder, leech hurry to get away, but even lethal concentration of chlorophos, probably not causing her pain. Zoologists, not without reason, believe that leech generally not feel pain. In any case, it does not flee, die on the spot.
Have leeches and other enemies. The worst - not fish not birds, and snails. They only think how to be small leeches. Likes leeches and muskrat. But vihuela now almost everywhere or not, or by the handful.