Answer:
Viruses needs to inject the virus to an organism's body, or host cell and duplicate as many viruses, so it can be able to insert it's own clones and take over the body sooner :3
Explanation:
:3
Circulatory system.....circulates blood (a vital delivery system of oxygen) throughout the whole body when tissues need it the most and with a constant supply.
In addition to gravity, muscular peristaltic waves, originating in the renal pelvis, squeeze urine down the ureters and squirt it into the bladder, the peristaltic movements consist of radially symmetrical contractions and in the relaxation of the muscles that propagate in a wave downwards in the muscular tube, in an antegrade manner, such movements are also found in the esophagus and stomach.
It was from darwin he was the 1