Modern Day Zombies in the Animal World

So the zombies that we see in movies aren't exactly the same kind that are being dictated within those two webpages. One of the articles consist of a wasp that attaches its larvae to become parasites of spiders and to use their abilities in order to survive. That'd be the same as the zombie virus (or whatever) manipulating and using human bodies in order to function and spread. The spiders build a home for the wasps and then are eaten by them. Not a good way to say thank you, I think. Anyways, I also find that the zombie fish are pretty neat too. They go back to the place they were born in order to die and spawn. They are literally killing themselves in the process of doing so. Their muscles and flesh are softening from the change of scenery and objects they run into. It's kind of cruel to think that they're programmed to do so. Like, cruel of nature is what I'm meaning.