Several of our friends at Bryan College are working on problems about natural evil - how did predation come about in a world that was supposed to be "very good"? Currently, they are looking at nematocysts as killing machines - delivering toxins that stun or kill the victim.
One thought was that the nematocysts were originally less toxic - perhaps delivering something less than a killing blow. One thought was that perhaps symbiotic relationships might affect the toxicity of the sting. As a model system, the Bryan College team began by studying the feeding habits of green hydra, who use nematocysts to stun and kill their prey before eating them. They were fed Sea Monkeys (Artemia) and their feeding patterns were observed. Unfortunately, the toxins were too toxic to the Artemia to be of use in toxicity assays, but they managed to garner some cool Hydra feeding videos in the process. All of the videos are sped up in order to make it a little more exciting. However, for a true-speed video, here is a Hydra swallow in real-time.
Anyway, many thanks to the BryanCORE guys for lending me the videos! For more information, you can read the research abstract (it is abstract C2).