The Phylum Cnidaria are very interesting. They are free swimming marine animals. Jelly fish have so many neat features about them such as there tentacles that can sting, the ability to function without a brain and also the way they move. They are very interesting to observe. They aren't opaque so you can see through them and look and all the neat features. They have long tentacles they move in a jet propulsion motion.http://ataillah.tripod.com/jellyfish.htm