The only unusual or abnormal facet to the Vulcan heart is its extreme muscularity. The heart walls are thinner, but stronger and more flexible than those of the Terran heart, allowing for a greater pulse range and a greater volume of blood. The kidney is a major part of the superior water retention system, a necessary component of life on a hot, dry world. Vulcan urine is extremely rich in excreted minerals with a high specific gravity, and will kill plant life. It is also extremely thick and viscous, resembling in colour and texture freshly-pumped crude oil.
Vulcan feces are dry pellets with all moisture removed.
Those familiar with owl feces will quickly recognize that, as with this bird of prey, the Vulcan digestive system completely removes all moisture and nutrients from food, leaving the excrement as a dry, extremely dense, compact mass. The ductless glands of the Vulcan are, unlike those of Terrans, under self-control and not autonomous systems. The thyroid can also be controlled to change metabolism. The female Vulcan is always capable of being impregnated by the male. A Vulcan male can mate any time, but MUST mate every 7 years during pon farr.