•  Osmosis is a diffusion of molecules through a semipermeable membrane. Its from a place of higher concentration to a place of lower concentration. It continues until the concentration on both sides are equal.
• If a jellyfish didnt go through this process its cells would burst causing the jellyfish to die .

simple diffusion

• Simple diffusion is the movemnt of substances from a region of high concentration to a region of low concentration. It does not contain the use of ATP! It's a physical process.
• oxygen and carbon dioxide are an example of why jellyfish need simple diffusion

how many chromosomes? 

Some Jellyfish species have up to 216 chromosomes!