Source: Star Fleet Medical Reference Manual (pg 52-55)
1. Vulcanoid species comprises almost 1/3 of the sentient life form in the Federation.
2. Vulcanoid population, excluding Romulan offshoots, was estimated at 21 billion by the Galactic Census of Stardate 5840.
3. Vulcan is extremely hot and dry, with a lower oxygen content and a somewhat higher gravity than Earth. Thus, the Vulcan had to become adapted to these living conditions, not only to become Vulcan's dominant species, but for simple survival. This is not to suggest the Lamarkian explanation that form adapts to function - no, Vulcan evolution follows standard Darwinian theory.
4. On Vulcan, the conditions are more uniform and harsh than those of Earth, so that Vulcans are more specialized and homogenous than Terrans.
5. The Vulcans never developed separate physical or "racial" types because Vulcan's climate and living conditions are more homogenous than Earth's. The comment that "all Vulcans look alike to me" has some basis in fact.
The Vulcan eye is protected by a clear inner eyelid (nictating membrane) that filters out harmful radiation, heat and dust, all elements present on Vulcan.
The eye itself if very similar to the human eye except for its range of colour differentiation for high frequency waves (the ultra-violet range) which is less acute, while night vision (low frequency waves in the infra-red) is more acute.
Laboratory tests found that the unusual, special shape of the ear helps to funnel air and intensify sound in the dry, thin air of Vulcan.
The Vulcan nose is very similar to the Terran nose, but not nearly as efficient an instrument of smell. It is, however, highly adapted to filtering air and passing it on to the lungs. Since 60% of taste is in the sense of smell, Vulcans have a notorious lack of taste sensation. This, however, does not hinder the Vulcan's enjoyment of food (or lack of enjoyment), as the Vulcan is strictly vegetarian (my comments: except that Tuvok ordered a burrito on one episode).
The one essential difference is that Vulcans have only 28 teeth, as they lack one pair of back molars.
The Vulcans are an extremely dolecephalic (long-headed) people.
Their brain case is approximately 0.2 cm thicker than Terrans and the bone itself is harder than the Terran skull.
The Vulcan brain is of the same overall structure and size (1600 cc) as that of the Terran. Only the midbrain area where telepathic and telekinetic powers originate is the Vulcan brain significantly different. The Vulcan midbrain is somewhat larger and more convoluted than the Terran midbrain and this, in part, explains the psionic powers of the Vulcan people.
The male Vulcan does not possess the protective supraorbital taurus (bony ridges) above the eye than Terran males often have.
OVERALL BODY - SIZE AND SHAPE
Vulcans, like Nilotics and Australian Aborigines, are a tall, slim people.
Males average 2 meters in height, and 70 kilos in weight, females 1.7 meters and 50 kilos.
Arms and legs are long and slim with extremely lengthy and powerful muscles attached to a medium frame
Vulcans are high-waisted and short-bodied as a rule, and make excellent long-distance runners.
The size and shape of the Vulcan postulates a convergent evolutionary trend with the Nilotic and the Aborigine of arid, hot, and dry lands.
Their body structure aids in the dispersion of heat through radiation. Concommitant with this is the lack of sweat glands in the Vulcan, as he uses blood, skin and body structure to cool himself, instead of the Terran way of heat loss through evaporation of perspiration.
The Vulcan epidermis, unlike human outer skin, is a two-way moisture-proof shield. Not only does it act as a waterproof barrier allowing cells to live in a fluid environment even in relatively dry air, as does human skin, it also allows available environmental moisture to be extracted for use by the body.
Highly specialized cells in the dermis, known as hyalothermonic cells, permit more efficient body heat loss with retention of water than does human skin (because of an absence of these specialty cells).
HEART AND LUNGS
The average Vulcan heart rate is 242 beats per minute.
The average blood pressure is 80/40 (systolic over diastolic).
This is explained in part by the extremely dilated blood vessels of Vulcans. Larger diameter blood vessels are an additional aid in cooling the body, allowing for greater cooling surface.
The Vulcan heart is located where one would expect to find the Terran liver, leaving room for the somewhat larger Vulcan lung assembly. In consequence, the cartilage (ribs) that normally protects the Terran heart extends an extra 3.5 cm downward in a Vulcan in order to protect the heart.
Vulcan blood is a copper-based compound and is green in clolour. Copper-based life aids in the utilization of oxygen under the low atmospheric pressure, low oxygen conditions on Vulcan. Blood cells are biconvex in contrast to the concave cells of Terrans. This convex shape also aids in cooling individual blood cells, the entire blood stream, and finally the entire Vulcan body.
Another feature of the Vulcan blood cell is its ability to take in and stare large amounts of oxygen in a thin, oxygen-poor atmosphere. A Vulcan can survive for hours under water or in a non-breathable atmosphere due to his unique blood cells. (my comment: I'm not so sure about this part).
The Vulcan lung is somewhat larger in size than Terran lungs. The alveoli in the Vulcan lung are 75% more elastic and are more efficient oxygen procurers than those in human lungs.
The Vulcan heart is also somewhat larger by Terran standards, but well within the normal range for humans. Its increased size relates to the increased workload of the heart. 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.
KIDNEY AND EXCRETORY FUNCTIONS
The kidney is a major part of the superior water retention system, a necessary component of life on a hot, dry world.
In humans, input = output, the Vulcan excretes only 50% of the liquid matter that the kidney processes, the other 50% is purified by the kidneys and recycled throughout the body. 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 individual adult Vulcan can regulate the amount of adrenalin and so speed up or slow down their internal systems in response to environmental conditions.
The thyroid can also be controlled to change metabolism.
By stopping the flow of thyroxin and adrenalin, the Vulcan can go into a state of suspended animation, very much like the trance state of the Indian Fakir. During this state, the Vulcan can command bodily resources (blood, lymph, etc) to repair damage. Thus the Vulcan had control bodily functions that are considered autonomous by Terrans.
The one gland system that the Vulcan cannot completely control is that of reproduction.
The female Vulcan is always capable of being impregnated by the male. The male, however, is only capable of sex approximately once in every seven years. (my comment: I was always under the impression that a Vulcan male can mate any time, but MUST mate every 7 years during pon farr.)
This is one of the central facts of Vulcan existence. In the pre-historic phase of Vulcan, men fought to the death regularly for the right to mate with females. This kept the population down, and hindered the growth of Vulcan society as men would not co-operate with others who could seen be their deadly enemies. When the Vulcans decided to master all emotion, they realized that they must first lessen the deadly lust males experienced before mating. At first, each male was forced to control this urge by sublimating and repressing the physical symptoms. But once every 7 years, the urge to mate becomes so overwhelming that the Vulcan male must do so or die.
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