Jellyfish falls under the phylum Cnidaria which means that it does not have a circulatory system. Instead they use the process of diffusion to allow important materials such as nutrients and oxygen throughout the body. The cells inside the body are the main receivers of all the nutrients that come in from the outside . The process diffusion is what allows all this to take place for example it is what what allows all the nutrients and oxygen to reach the jellyfish's skin and with all this the jellyfish can live it's normal life with the help of an old buddy called diffusion.