Tetrapod probably had a three-chambered heart, as do modern amphibians and reptiles, in which oxygenated blood from the lungs and de-oxygenated blood from the respiring tissues enters by separate atria, and is directed via a spiral valve to the appropriate vessel — aorta for oxygenated blood and pulmonary vein for deoxygenated blood. The spiral valve is essential to keeping the mixing of the two types of blood to a minimum, enabling the animal to have higher metabolic rates, and be more active than otherwise. The difference in density between air and water causes smells (certain chemical compounds detectable by chemoreceptors) to
Tapping the Vein (comics) Tapping the Vein (comics) Tapping the Vein is a comic series of Clive Barker's short stories from "The Books of Blood" published by Eclipse Comics between 1989 and 1992. Eclipse Books would continue to adapt various Clive Barker short stories in the early 1990s after the "Tapping the Vein" series came to an end. These include the following: (A single volume featuring just "Dread" was also published) (A single volume featuring just "Revelations" was also published) Advertised, but never published was an adaption of "The Age of Desire" by P. Craig Russell and Tim Bradstreet, from "The Books of Blood