Flatworms and jellyfish don't have a circulatory system and in these animals, the oxygen is diffused through the cells.
Through the process of diffusion
diffusion
the heart pumps oxygenated blood back to the lungs
By the process of simple diffusion.
Hydra cells get oxygen through diffusion.
Through the process of diffusion
"diffusion"
diffusion
By the process of diffusion
diffusion
Diffusion.
diffusion
Oxygen is able to go into a cell by diffusion. The oxygen molecules are small enough to go through the cell membrane with that process.
diffusion
Diffusion
the heart pumps oxygenated blood back to the lungs
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