As the shark's activities grew more and more frantically vicious, he sent exploring pseudopods over the ugly rough-skinned form, and within a few moments discovered the five gill slits on each side of the creature's neck. That was enough. He no longer investigated; he acted, with a skill and precision born of long experience.
The Hunter was a metazoon-a many-celled creature, like a bird or a man-in spite of his apparent lack of structure. The individual cells of his body, however, were far smaller than those of most earthly creatures, comparing in size with the largest protein molecules. It was possible for him to construct from his tissues a limb, complete with muscles and sensory nerves, the whole structure fine enough to probe through the capillaries of a more orthodox creature without interfering seriously with its blood circulation. He had, therefore, no difficulty in insinuating himself into the shark's relatively huge body.
He avoided nerves and blood vessels for the moment and poured himself into such muscular and visceral interstices as he could locate. The shark calmed down at once after the thing in its mouth and on its body ceased sending tactile messages to its minute brain; its memory, to all intents and purposes, was nonexistent. For the Hunter, however, successful insterstition was only the beginning of a period of complicated activity.
First and most important, oxygen. There was enough of the precious element absorbed on the surfaces of his body cells for a few minutes of life at the most, but it could always be obtained in the body of a creature that also consumed oxygen; and the Hunter rapidly sent sub-microscopic appendages between the cells that formed the walls of blood vessels and began robbing the blood cells of their precious load.