Anatomy & Physiology

Skeletal Representation

Dragon bones are not easily broken unlike a human. The design buffers takeoffs and landings effectively, and animal meat (which on Pern contains Boron) sustains skeletal strength, much like humans require milk products (for the calcium). They have a stronger endoskeleton (outer skeleton) than us and so, despite their size and form, are comfortable upright. The skeleton itself is constructed of light flexible plates that are designed to glide over each over. A modified ball and socket joint in their hips prevents their knees from dislocating during the powerful thrusts needed for takeoff and during the absorption of impact on landing.

The ribcage of a Dragon is comprised of a single piece, unlike a human, and is surprisingly large. Despite being constructed from a single piece, ribcages rise and fall, and thus some muscles and ligaments must allow for this, probably a huge diaphragm. Dragons chests can double in size upon full inflation, presumably to deal with working under pressure and at altitude.

A Dragon wing is particularly complicated, comprised of many bones which allow it to extend, flex and furl. The easiest way to describe the skeleton of a Dragon wing is to consider the structure of a sail on a boat or a modified human arm. Two wingbones extend outward from the shoulder joint, running almost in series to each other, but separated by the 'elbow', the bones forming the 'lub'. These wingbones conclude in the finger joints, where the spar bone forms the outer edge of the wing. The mid-bone and inner-bone also extend outwards from the finger joint, sometimes known as a wingspar or pinion, jointed themselves several times, like the spar bone, to provide flexibility (see Wing Structure for further information).

Muscular Representation

Dragons are heavily muscled, their back legs in particular are massive, enabling them to leap far off the ground on takeoff. In appearance the muscles glisten silver-grey in colour, with the grey becoming darker, and greener, where the ichor supply is richer.

Dragon forelegs are much shorter than their rear limbs, appearing more like modified arms than legs, and the shortness lends them an ungainly hop-skip movement when walking. Therefore, they have a tendency to relax in an upright, 'sitting' position. Firelizards limbs are more equal in length and musculature than Dragons, which means they spend less time in an upright position.

Talons

Dragons have pentadactyl (five-fingered) claws, jointed much like a human's hand to allow adequate purchase. On the other hand, Watch Whers only have two claws instead of the five, with a single pad on which to rest their weight on. Long, sharp talons are found on the front limbs, which are excellent for hunting. The rear limbs have softer nails, but these are still stronger than humans'. Dragon talons are similar in nature to canine claws, and even our own fingernails. They are made of keratin, and grow out from a talon bed, which is situated in the foot pad. Thus, the talon itself has no nerves associated with it, and therefore no feeling, until it reaches the point where it grows from the talon bed. There it is nourished with ichor and nerves. However, that's not to say they cannot feel by association through their talons, though it is more correct to say that they feel the connection through the talon to the talon bed.

Hide

Dragonhide is not metallic in nature, neither is it constructed of 'scales'. It is extremely resilient to most abrasive injuries, and is smooth, soft to the touch and hairless. Healthy hide is glossy, with no hint of grey underlying the main colour and needs to be constantly cleaned and oiled, otherwise dry, patchy spots may develop, which may crack on trips between and cause great pain.

Dragonhide epidermis is known to be thick and extremely resilient to most abrasive injuries and provides, like human skin, a barrier to infection. However, absorption of topical substances is still possible. For example, Numbweed will numb the outer area in around three seconds, though it takes a little longer to penetrate the epidermis to the germative layer and thus dissipate the pain.

Female Dragons often experience a change in colour tone before they rise to mate. They may even appear to glow. The colour change differs in golds and greens. In greens it can occur up to a full day before she rises, golds on the other hand rarely show a colour change until they are ready to mate (see Mating Flights for further information). Male Dragons do not generally experience a fluctuation in colour, although their hides may deepen in colour with age and become wisped with grey (see Maturity for further information).

Temperature

Although their body temperature (35°C) is slightly cooler than humans (37°C), Dragons are definitely warm 'blooded', this can be determined by their reaction to hot and cold temperatures. However, they do not have blood and it is not even red in colour. Instead they have ichor which is dark green in colour. Ichor, like blood, is also based on a metal, in this case the metal being copper instead of iron. Dragon flesh does therefore have a green tinge to it instead of pink normally associated with humans.

Ichor

Ichor circulates around the Dragon in a continuous cycle, pumped by the rhythmic contraction/relaxation, or beat, of the heart muscles. The typical lub-dub of the hearts are due to first the atria (upper heart chambers) filling with ichor, and then the contraction of the atrium muscles filling the ventricles (lower heart chamber). This, however, is a further complication in a Dragon that has multiple hearts. Since Dragon carcasses are not readily available the exact number of the hearts is unknown. The reason for multiple hearts has never been discerned, but it is thought that this may be due to the effects of altitude and exertion during mating flights and Threadfall.

The ichor circulates within a network of flexible tubes known as ichor vessels, of which there are three types. Arteries are strong, muscular, elastic-walled vessels that carry ichor away from the hearts and towards the tissues. Veins are thin-walled and carry ichor back to the heart. Ichor is squeezed through the veins by the action of the surrounding muscle and is kept flowing towards the hearts by one-way valves. Capillaries are the smallest ichor vessels and bridge the gap from arteries to veins. The force, with which the hearts pumps the ichor through these vessels, and around the body, is known as the 'ichor pressure'.

Respiratory System

Dragons can inflate their dorsally-placed lung sacs to approximately twice their normally inflated size. Presumably this is to aid respiration under pressure at altitude and additionally may have a role in sustaining a constant flame. Since Dragon rib cages do not have the separate bones that humans do, they rely solely on the diaphragm and not on that and the intercostal muscles. The diaphragm of a Dragon is a huge band of muscle that pulls the lungs down, similar to a human, and into the ribcage, or pushes the lungs up, allowing air to move into and out of the lungs respectively. Curiously, they also snore, despite reports from Riders that suggest otherwise. This tends to be particularly prevalent within Weyrling Dragons. This is thought to be due to the fat to muscle content, which eventually levels out as they begin to eat less, and exercise more.

Digestive System

Dragon's tongues are not forked, and they have little saliva: just barely enough to protect from infection, and assist in masticating food and Firestone. Too much saliva would result in complications to the later reactions in the second stomach upon chewing Firestone.

Dragon teeth are strong and therefore difficult to break, a fortunate occurrence since they appear to have only one set. Age may weaken them, and therefore older Dragons may break teeth when chewing bones or Firestone. They are sharp at the front, canines, for hunting, useful for ripping and rendering, and more molar like at the back of the mouth for chewing Firestone and meat.

Dragons have two stomachs, one is for food, and the digestion of such, the other is for Firestone, and the complex reaction that is necessary in order to generate flame. Early on Dragons learn to concentrate on their second stomach when chewing Firestone. Ingestion of Firestone, and passage into the second stomach, initialises a complex chemical reaction, catalyzed by an acid. Once the chemical reaction has been completed in this second stomach, then a number of flammable gases are produced, which, when belched forth, ignite on contact with air. An experienced Dragon can sustain a flame for well over a minute and flame range can be varied from around 6 to 2 metres. Dragons disgorge the ash when they go between.

A digestive tract for the second stomach does not exist, unlike for the first which passes to the tail. Therefore, the Firestone, which has been masticated and subsequently digested inside the second stomach to an odourous ash, is not excreted but disgorged. As Weyrlings, Dragons regurgitate in ashpits near the Weyrling barracks, but once between training is underway, Dragons will disgorge the contents of their second stomach between. They may also be asked by the Holder's to disgorge contents for use as fertiliser.

Golds do not ingest Firestone; the weyrwomen therefore use Flamethrowers in Threadfall, which have as much variation in range as a Dragon. However, since gold Firelizards ingest Firestone, flame and still bear live clutches, it is believed there is something in the genetic makeup of a green Dragon that makes her infertile, and not the Firestone. Considering the frequency at which greens rise, this is somewhat of a relief to any Weyr, but no weyrwoman would consider testing this theory.

Dragons have forked tails, almost arrowhead in shape. Their sphincters are located towards the base of the tail, and excreta is stored up for several days here until they are able to go between and get rid of it. Weyrlings and infirm Dragons that cannot go between need to have their Rider muck out their couch or Weyr.

Wing Structure

The wingspan of a Dragon is typically 1 and 2/3's their length and, because the wings function somewhat like sails, the terms used are quite similar. Whers have short stubby malformed wings, and are incapable of flight. Approximately half the length of the wing is supported by bones that are reminiscent of a human arm between the shoulder and finger joint, including an elbow.

Two wingbones extend outward from the shoulder joint, running almost in series to each other, but separated by the 'elbow', the bones forming the 'lub' portion of the wing. It is the inherent strength of the shoulder and upper arm muscles that provides the necessary power for a downstroke of the wing, with the elbow usually held in a slightly flexed position. The lower arm terminates in the finger joint, and a membrane that stretches from here to the shoulder is known at the leading edge, whilst the one that extends from the arm and finger joint to the leech is known as the trailing edge. One of the bones at the finger joint, the spar bone, forms the outer edge of the wing, running down to the outermost, or forestay, tip, of the wing. The mid-bone and inner-bone also extend outwards from the finger joint, jointed themselves several times, like the spar bone, and provide excellent flexibility.

The finger joint is constructed in a similar fashion to our hands, and includes the metacarpals (what are known to us as the hand bones), a vestigial (unused) 'thumb' and all the joints for the wing bones. The muscles responsible for extending (extensor) and flexing (flexor) the wings start just below the elbow, narrowing into long tendons as the reach the finger joint. Additionally, they extend along all the wingbones and are attached at each joint, allowing fine control of the wingtips.

Schematic Representation of a Dragon Wing

Copyright H.Walter 1997

There are three membranes that make up the wing: the primary mainsail, the secondary mainsail and the spar mainsail. The primary mainsail stretches from the dorsal spine and shoulder, stretching to the inner bone and forms that largest of the three membranes that comprises the wing. It is this membrane that supports the majority of the body weight. The secondary mainsail extends from the inner bone to the mid bone, whilst the third mainsail, the spar mainsail, runs from the mid bone to the spar bone. As well as providing support of the body's weight, these latter two mainsails provide manoeuvrability. The membranes can be manipulated by the tendons attached to the various joints, to provide movement in both the horizontal and vertical planes. The outermost tip of the spar mainsail is termed the 'finger sail' since it is able to function almost independently of all the other mainsails.

The wing membranes are nearly translucent in Dragons, although thicker over the bones and muscle attachment points. However, they are significantly stronger than they appear. Additional support of the primary mainsail is provided by a number of cartilages which extend from the arm and finger joint towards the trailing edge and referred to as 'batten ribs'.

Senses

Dragons have known to have the share the same five senses that we do, those of sight, sound, taste, touch and smell, which are all present in different stages of development. In addition they have a sixth, and highly developed, sense, that of telepathy.

Dragons have no ears, their headknobs appearing to fulfill this function as they do react to noises that are not related to their sixth sense. Watch Whers also have headknobs that they use as audio receptors, however, their primary mode of communication is telepathic.

Dragons do not have eyelashes, their eyes being protected both by prominent eyeridges and by three sets of lids: an inner transparent pair, and two increasingly thicker sets of membranes, the outer set similar in tone to their hide colour. Dragon eyes protrude outwards from their eyesockets, and as such provide peripheral vision that extends additionally to what is above them, a useful tool in Threadfall. Dragons can, if the pairing between the Rider and Dragon has been sufficiently developed, use their Rider's eyes to see something if they are not present themselves. This bond, usually developed in Weyrlinghood can be strengthened by forcing the Rider to rely on Dragonsight, and likewise with Dragon to Rider.

Dragon eyes are multifaceted, and the whirling, that is generally associated with emotion intensity, is in fact an optical illusion caused by these facets. Eye colour reflects mood: green and blue signify contentment, yellow indicates fear, reddish orange signal anger, red expresses hunger, white denotes danger and purple suggests the mating urge and love. Additionally, Dragons, like whers, can see in the dark. Watchwhers, though, while having excellent sight even in total darkness, are photophobic, and have poor focal length. Dragons on the other hand have good focal length, being able to see objects on the ground from at least several Dragonlengths above ground, if not further.

Smell is poorly developed within Dragons. They cannot smell anything distasteful in the stench of Firestone, but can, however, smell well enough to detect 'strange' and unfamiliar scents. Sensitivity to touch seems to vary as it does in a human, with Dragon bellies having been noted as ticklish.

Dragon tongues are not forked and their teeth are strong. Their front teeth are extremely sharp, ideal for hunting, whilst their back teeth are more molar-like, perfect for chewing Firestone. Little is said about taste. However, taste buds probably do exist, but aren't that well developed, certainly not as much as a human, and detecting sweet from sour is almost certainly impossible. The ability to discern between food and Firestone to direct it to the correct stomach (see Internal Systems for further information) does exist, but whether it is texture or taste is hard to identify.

Their sixth sense, that of telepathy, is highly developed, and they are able to bespeak any person should they choose to do so. Dragons also have an excellent spatial sense. This is particularly useful when emerging and going between and is the reason why they don't collide with others Dragons when arriving into a crowded airspace.

Reproductive Systems

Dragon genitalia are concealed behind pouchlike flaps of hide under the junction of tail and body, and are only revealed during mating.

Three months after the mating flight, the Gold clutches her eggs on the hatching sands. Then, for five sevendays, the eggs harden, and the dragons develop until they are ready to hatch.

At the onset of a Dragon hatching, the dam will emit a noise that is described as more 'subliminal' rather than actual noise. The Gold will then begin to show external signs of excitement, her chest and belly vibrating with the noise she is generating. The other Dragons start to hum, the sound continually increasing in volume. Riders have been noted as feeling slightly deafened after a hatching.

Dragonets hatch from their eggs complete and in urgent need of food, although they seek to impress to their lifemates first. They will circle the sands searching for their lifemate, screaming until they do so. Accidents where candidates get trampled by the Dragonet eager to find his or her lifemate are common.

Impression

It is unknown what creates an attraction between Dragon and Rider. Nevertheless, it seems to be present from the moment of hatching and Dragon choice can neither be forced nor changed. Once impression is made, they start to feel hungry.

Impression is often described as the most wonderful experience by Riders and they will often get wistful if asked. The sensations overrunning the new Rider are complex and more than one has felt confused because suddenly they have two sets of emotions instead of one. A distressed and agitated hatchling can bespeak every Rider in the locality if need be, and, even with a newly formed bond, Dragonets are fiercely protective. They will, with provocation, attack a human that endangers their lifemate.

Intelligence

Considerable intelligence is displayed by Dragons. However, their memories are notoriously short, their recall lasting from 2-3 days. They seem to have particular problems in remembering specific events and names, frequently slurring or compressing syllables. In fact, this is the origin of the honorific. Some Dragons are reported to chat incessantly, whilst others rarely speak except to express an opinion. Riders on the whole tend to be biased when their lifemate is under consideration and will often be close mouthed about what their Dragon has said.

Dragons rarely communicate directly with anyone but their Rider, but they do have the ability. Generally it is assumed that they do not usually feel the need to communicate with others, but when they do, it is usually only in short phrases.

It seems that certain matters do interest them, since they can be highly intuitive about what affects them and their Riders, and in leading Dragons their Wing or Weyr, with some Dragons offering suggestions on problem solving.

Dragons do seem to have some difficulty relating cause and effect. For example, if a Dragon saw his Rider making straps, the Dragon wouldn't necessarily correlate that to his Rider's increased safety during Threadfall. However, they do possess an instinctive inbred hatred and reaction to Thread and are difficult to dissuade from attacking even if they aren't stocked with Firestone.

Dragonet's

A newly hatched Dragonet has a jaw that will fit over a man's head, although their teeth are not fully formed. Since they do not need to hunt, the lack of the front teeth is not important.

Dragonets feed six or seven times a day during their first month, but eventually this evens out to around twice a sevenday by the end of the first Turn when they are hunting for themselves. The new Riders are responsible for feeding their lifemates, although the first morning after impression a pail of meat is provided for the new pairs. After that, Riders are responsible for carving up the meat for their lifemates, chopping the morsels into small pieces. After feeding the Dragonets sleep, and then generally need to be bathed and then oiled.

Dragons take between a Turn and a Turn and a half to reach maturity and full growth. However, they remain in proportion throughout their development, with their wingspan at 1 and 2/3's of their length. Gold Dragons grow to be the largest Dragons, ranging between 38 to 42 metres in size. Bronzes range between 35 to 38 metres, whilst Browns, Blues and Greens range between 30 to 35, 25 to 30 and 20 to 25 metres respectively.

Young Dragons are discouraged from flight until their muscles have been developed sufficiently, usually at around 8 months. As a young Dragon approaches maturity, the Weyrlingmaster will allow them to carry their Riders, briefly at first, but increasing to build muscle strength and allow them to fly through an arduous 6 hour Threadfall.

Similarly, young Dragons are prevented from going between until their Riders mature and have achieved sufficient control over their emotions. This delay also ensures that the bond, partnership and reliability on each other has developed. Probably due to their short memories, Dragons rely on the images given to them by their Riders, or other Dragons. Without a clear visualisation, a Dragon will risk never reappearing, and thus Dragons are rarely permitted between on their own.

Dragons also possess the capability of going between time, though inherent dangers are involved in this. Not only does a Rider risk meeting themselves, it also places a great strain on the Rider. Generally, a Weyrleader will not permit Riders to 'time it' and anyone suspected of such will be severely disciplined.

Mating Flights

Greens generally tend to rise to mate as soon as they are mature. However, Golds do not seem to rise until well after their second Turn and sometimes it is later than this. The reasons for this are purely speculative, but may be in some part due to the egg-laying process. As a rule Greens rise to mate approximately four times a Turn. Golds rise less often, about twice a Turn.

Female Dragons generally show a change in colour as an indication of rising to mate. This colour change occurs a few days before a Green will rise, her Rider generally becoming irascible and displaying uncharacteristic behaviour. In Golds this may differ. A Gold generally shows no colour change until the day she rises to mate and, on that day, she is usually sleepy, wakening from a deep slumber only when she is ready to rise. Her Rider may show signs of 'proddiness' a day or two before she rises. Threadscoring and similar traumas can cause a Dragon to rise unexpectedly, with little or no warning.

When a female is ready to rise, the males sensitive to her are induced to blood their kills. As she awakens, primitive instincts take over, and she must be prevented from gorging by her Rider. This is extremely important, since a full-stomached female may not achieve the height necessary to successfully mate before crashing to the ground.

Territorial drive within Golds is extremely strong during mating, and all other Golds, unless egg-heavy or attending to a clutch, should be removed from the Weyr since a mating Gold may induce heat which will ultimately result in a battle, each trying to keep 'her' males. It is somewhat advantageous that Greens are less territorial, since their sheer numbers would be extremely disruptive to the Weyr.

During a flight, the male sexual drive is largely competitive. They generally finish blooding before the female, due somewhat to the fact that they started before the female and also to the fact that they watch for the sign of the female rising into the air, seeking to be close behind her as she leaves the feeding grounds. He will seek to out manoeuvre the other males and catch the female. Different techniques seem to be necessary to catch Green and Gold. The Greens are more agile, but tire quicker, whilst the Golds are somewhat slower but have more endurance than all the males. Aggressiveness is an integral part of some mating flights and a Dragonhealer may need to be on hand.

Greens may mate with any male Dragon, but only Brown and Bronze Dragons have a chance of catching a Gold. No Gold eggs and very few Bronzes are produced from Brown-Gold pairings. They are highly discouraged in Senior Golds, even though the offspring are healthy. Longer, higher flights generally result in a greater number of offspring and a higher ratio of metallics to chromatics.

Only Gold Dragons are fertile, which was thought to be related to their ability to digest Firestone, however there is some speculation on this point. They produce clutches that range from ten to forty eggs, with occasionally one or two 'dead' eggs, which are generally of no concern. Typically a Gold is gravid for twelve to fifteen sevendays. The eggs then spend five weeks hardening on the heated sands of the Hatching Ground before hatching.

As they mature, Dragons display various signs of aging. These include greying of the muzzle, stiffening of the joints and, occasionally, loss of teeth. However, the former may be related to the rigours of Threadfall and training.

During a Gold Dragon's lifetime, it is common that one or two 'dead' eggs are produced, but as she ages they may become more numerous. A Gold may also stop producing clutches or rising to mate.