Hydra sponge TURBELLARIA there is no blood circulation system. Each cell can exchange gas through direct cell membranes as well as single-cell creatures .
Hydra sponge planarians with no circulatory system. Cells, each cell will change Pioneer Gas directly through the cell membrane as well as single-celled organisms.
Sponge, Hydra planaria. No circulatory system. The cells each cell will exchange and เก๊ส through cell membrane directly, as well as single cell organisms .