Every cell needs oxygen and energy to live, and it needs those all the time. An organism needs an efficient way to distribute oxygen and energy or cells will die. With animals on earth, a heart pumps blood through blood vessels. The blood gets to individual cells through smaller vessels called capillaries. With plants there is also a flow of water up from the roots and food down from the leaves. This is accomplished by using capillary action and pulling the water up as it evaporates. Plants are able to circulate fluids without hearts, but a pump may be essential for organisms that need to be able to move quickly.
The snorvep's blood is pumped around the body
by two pulsing nodes, one just below the hearing organ and one
near the back tentacles. You can see the main blood vessel and
supporting blood vessels in black in this picture. There are lots
of capillaries in the breathing system, and many more in the hearing
organ. The tentacles are served by smaller blood vessels. Note
that the major blood vessel goes right by the digestive tract
so that it can pick up food for the cells. It also goes along
the brain so that this organ can be nourished.