No one likes to find that they have hydra infecting their shrimp or crayfish. This article provides some interesting insights to how hydra live.
Here's the direct link if the link above does not work.
http://io9.com/5890685/hydra-dont-need-brains-or-even-eyes-to-see
Here's the direct link if the link above does not work.
http://io9.com/5890685/hydra-dont-need-brains-or-even-eyes-to-see