Appendix C

          Reys are the masters of the Jopian skies. They spend their entire lives in free flight, far from the protection and support of the floating thickets. Reys have the largest natural vertical range of any complex Jopian life form – from a sultry, crushing 570 kilurets depth, to the icy, rarified upper reaches of towering water storms that breach the tropopause.
          Reys are not solitary creatures, but nomadic social mannavores, that live and travel together in tribes. A tribal unit is a close-knit group of up to a several hundred individuals, usually led by a council of elders. Most reys remain in the same tribe from birth to death. There are only two rey sexes/genders – male and female. While tribes generally steer clear of each other, occasionally (perhaps once in a rey's lifetime) a tribe will intentionally seek out another, in order to exchange males. Tribes tend to be matriarchal; female ancestry normally defines tribal identity, and a female will leave her birth tribe only if forced out by the leadership. If a tribe grows too large during times of plenty, it will divide into two.
          A mature adult rey has a flattened conical body, typically just over one-half ret across at the front, and about two and two-thirds rets long. It is topped toward the front by a prominent cerebral hump, and tapered at the rear to a graceful yet powerful tail. A tough, smooth, silvery skin/hide covers all exterior surfaces, providing protection and insulation from temperature extremes. Two rounded, billowy wings extend from either side, spanning up to three and one-half rets tip-to-tip. A sieve-like mouth, used to filter microbes from the air during feeding, is located near the front of the body underside. Much as with deep-sea Earth creatures, a pair of internal buoyancy sacs (in this case filled with pure hydrogen) aid with depth control. A Jopian rey appears superficially similar to an Earth ray, except for a more pronounced cerebral hump, and the eyes.
          A pair of optical eyes, sensitive to three primary infrared colors, lie on opposite sides of the upper rey "face" (the forward surface of the cerebral hump). These eyes are useful in many situations: at the cloud tops, for viewing suollit objects (other reys, distant cloud patterns); through midrange depths, for detecting objects warmer than the ambient air (other reys, distant turbulent water clouds); and at the bottom of the rey range, for locating nourishing hot springs. The three primary colors are optimized for these distinct functions.
          A second mode of rey vision is based on high-frequency sound. This system evolved to help the rey's ancestors negotiate the floating thickets, and avoid serpent predators. Today, it is also used for communication. Two modes of operation are available. In the more common active (or pulse) mode, bursts of ultrasound are emitted from a bellon – an organ at the center of the face, below and between the infrared eyes. The sound can be focused, from a narrow to an open beam, and aimed in any forward direction. Returning echoes are imaged by a pair of large, deep-set acoustic eyes located on either side of the bellon. Each eye is covered by an array of sonoreceptors sensitive to both the amplitude and the phase of incident sound at select frequencies. Neural circuits reconstruct images, based on the detected pattern of echo amplitude and phase. Two narrow frequency bands are utilized simultaneously: an upper channel (centered on about 600 kiluhartz, or 300 kilohertz in human parlance) for closer, detailed vision; and a lower channel (around 100 kiluhartz) for longer-distance, lower-detail viewing. The latter sound waves travel with much less attenuation through the atmosphere, but suffer considerably more diffraction. The dual-frequency format helps to distinguish true personal echoes from extraneous sound, and differences in reflected intensities provide a sense of color-texture. The intervals between pulse emission and echo detection are timed autonomically, creating a keen sense of depth. Phase-based imaging and parallax between the eyes provides supplementary inputs for depth perception.
          This pulsed system is finely tuned. Individual reys can reflexively adjust the central frequencies of their own visual bands over a limited range, to avoid interference with others nearby. The system is also very sensitive to tiny frequency changes within the two fundamental channels. Echo shifts with respect to the (current) central emission frequencies are perceived mentally as different hues of color, with two primary colors spanning each of the two visual bands. By detecting small deviations in the frequencies of returning echoes, reys gauge the line-of-sight velocities of nearby objects.
          The lower frequency pulsed channel also functions at a semi-autonomic level, under limited voluntary control, to maintain appropriate separations among tribe members. Weak wide-angle orientation pulses are issued at regular intervals, in particular during sleep. Returning echoes are processed subconsciously to create a sense of location within the tribe, based on the number and positions of other reys in the forward-facing hemisphere. Because the system is blind to the rearward hemisphere, an individual rey can only be responsible for maintaining safe distances from neighbors in the frontward and lateral directions.
          The acoustic eyes can alternatively function in passive mode, to visualize objects lit by ultrasound from extraneous sources, in particular other reys. Now the eyes simply detect ultrasound arriving from the environment. This mode is more broadly tuned, and operates with lower spatial resolution than active mode.
          At the outer edges of the acoustic eyes, on opposite sides of the cerebral hump, is a pair of ear-like receptors that provide reys a sense of hearing. These organs are sensitive to sound at 12 discrete low frequencies, extending from a few hartz to around 20 kiluhartz. In addition to the high-frequency pulses used for vision, the bellon can produce modulated sound at any of these auditory frequencies. The corresponding wavelengths are far too large for visual purposes, and are used instead for aural communication. The highly tuned design eliminates much of the otherwise deafening noise that often engulfs the reys. Unlike the visual acoustic system, which can be quite directional (especially in the upper channel), the auditory system is effective in all directions. Still, by detecting intensity differences between opposing ears, a rey can discern the general direction of even a low frequency source.
          Sound in the base auditory channel is capable of traveling huge distances with minimal attenuation. The rey autonomic nervous system causes the bellon to periodically emit a pulse of such sound. This allows different tribes to sense each other beyond normal visual range. It can also help guide a rey home, should it become separated from its own tribe.
          Rey precursors used the low-frequency auditory system for all communication. An ability to communicate visual images originated when their descendants began to reproduce acoustic pulse sequences received along a given line of sight, and beam them to each other. As the acoustic system developed, such messages became confined to a separate narrow, dual-color frequency range between the two fundamental vision bands, reducing the problem of visual confusion. The communication scheme gradually advanced to the transmission of complex pulse sequences representing stereotyped scan patterns across (portions of) the visual acoustic and (later) visual infrared fields.
          Reys now converse using this modified visual system, in addition to the older auditory apparatus. Symbolic auditory speech came first. Symbolic visual speech then arose quite naturally, when reys began to substitute standard pictograms for actual images in their visual communications. These became increasingly stylized and streamlined into compressed pulse sequences, until finally they lost all resemblance to the original, and were transformed into abstract logograms. Rey communication today consists of a rich mixture of symbolic auditory and visual content plus visual imagery, difficult to convey faithfully using human language. Unlike auditory speech, visual speech requires some degree of face-to-face contact. Visual speech is staccato – a series of pulses, beamed from one rey to another, who "reads" the flashing pattern with acoustic eyes. Visual speech content is determined both by the spatial-temporal pattern of the pulses, and to a lesser extent by the interplay of the two colors within the communication frequency band.
          The reys are especially fond of speaking and singing in verse. Because they have no written language in the conventional sense, one might expect reys to rely on strict forms of verbal meter and rhyme to facilitate faithful transmission of content from one generation to the next. Yet reys have since ancient times blended an eclectic mix of rhymed, metered, and free styles in their spoken verse. This may be attributed to the peculiar rey communication system, which combines parallel visual and aural elements. Visual images and symbols can be metered and rhymed in a way analogous to words. Pairing visual content with spoken words helps the reys avoid narrow reliance on human-like oral mnemonic techniques.
          While the life of an individual rey is centered on the tribe, the life of a tribe revolves around the cycle, or passage – a cyclic journey from the cloud tops down to the feed layer, and back. Though variable, the length of a typical cycle is about 17 yads (seven Earth days). Reys are born with a biological clock, and an innate (though comparatively imprecise) sense of the passage of time. Reys can count cycles, as well as many other quantities, and readily remember and process numbers up to four digits long. Unlike humans, whose ten digits naturally led to base-10 counting, or octos, whose eight tentacles led to base-8 counting, reys have no appendages. Their peculiar brain circuitry instead led to counting systems based on multiples of three. While some tribes use base-12 counting, the most common system is base-9.
          The overall passage is broken into four quads of unequal duration. The first quad starts near the icy top of a water storm, out of which the reys emerge after an exhilarating ascent from the steamy depths. For a strong cyclone, this high point can approach the tropopause itself, at the roof of the upper tropospheric circulation. The associated storm towers are some five times taller than their counterparts on Earth. The frigid temperature at the loftiest summits can be as low as 100 nevlu (some 160° Celsius below the freezing point of water), with an atmospheric pressure of only 1.3 rabs (15% sea-level pressure on Earth). Less powerful squalls peak lower in the atmosphere, typically in the upper reaches of the mid-tropospheric circulation (80 kilurets beneath the tropopause), down to levels barely surmounting the tops of ordinary water-ice clouds (some 18 kilurets deeper) in the weakest storms.
          The selected storm cell is typically at the edge of a large cluster, which is almost always associated with an underlying mammoth convective plume of hot, rising currents. As it ascends through the mid-tropospheric circulation, a plume normally separates into a complex of broad, undulating streams, known to the reys as rivers of fire along the lowermost sweeps of their range. These rivers in turn spin off the numerous hot springs and fountains on which the reys rely for food. As they surge into the water clouds, the rivers initiate and sustain the lightning storms. After riding powerful updrafts into a storm's billowy crown, the reys roll (or are hurled) out, into open air. This is a sacred moment, tied to innumerable myths and legends, as the reys enter an otherworldly realm at the pinnacle of their range.
          If conditions permit, receptive adults may now mate. Reproductive organs of both sexes occupy furrowed folds under the wings, along the lines where the wings attach to the body. A male and female approach each other, side by side with wings lifted, then grasp one another, spinning through the thin air. The male passes genetic material into the female, and fertilizes any egg cells. The female will hold these in stasis, until an opportune time. Normally only one embryo develops at a time. A typical pregnancy lasts about 12 cycles, or one gyre. Mature males are distinguished from females by their smaller bulk and more streamlined body shape. The robust female frame is more designed for strength and endurance, to carry young through the trials of the passage. A newborn rey attaches to its mother in a fold under her wing, suckling from a sinewy nipple for several cycles until it is ready to fly free.
          After mating, the reys assume V-shaped flying formations, and soar away from the local storms. Tribal leaders select a compass bearing, typically eastward with a slant toward the equator, as individual storm cells tend to drift westerly and poleward from the underlying plume head. Reys have an exquisite sense of orientation and direction, and even a weak sense of planetary latitude, based on a specialized organ that detects both the local magnetic field and the forces exerted by fluids circulating through a set of circular canals. Now the reys sleep, as they plunge through the frigid gas, and layer after layer of flat clouds. The tribe maintains its formation by means of the rey acoustic system, functioning in autonomic mode.
          The reys may glide 1,850 to 2,250 kilurets as they slumber. After some 10 to 11 rohs, at just over 270 kilurets depth, they awaken, and the second quad begins. The temperature has warmed to over 310 nevlu (approaching the boiling point of water on Earth), still a bit cool by rey standards, while the pressure has climbed to nearly 100 rabs (more than ten times sea-level pressure on Earth). The tribe regroups, forming a huge, half kiluret-wide cylindrical formation that spirals straight downward. The length of time for this formation to complete one rotation midway through the second quad is commonly called a turne, and is comparable to a human minute. Multiples of nine may be used to define periods that are shorter or longer than the turne. In particular, a fliq is about 1% (or 1/81 base-10) of a turne, or two-thirds of a second, while a coile is nearly 100 (or 81 base-10) times larger than a turne, or just over an hour.
          The second quad is a time for adults to socialize, for females to give birth, and for the young to play and receive training. The period typically lasts about three yads. A central event of the second quad is the community chorus. The chorus brings the tribe together both emotionally and spiritually, and also serves as a practice drill of the group response to an attack by ribbon serpents. These beasts are the rey's only predator, and generally attack along the bottom leg of the passage, when the tribe is feeding. The reys temporarily rearrange into a flattened ellipsoidal array, flying in unison at a slight downward angle, a typical feed layer pattern. The most vulnerable – elders, females carrying young, ailing children and adults – gather at the center. These are surrounded by immature but free-flying youth, interspersed with mature but childless females. The healthy mature males form an outer shell enclosing the others. To begin the chorus, cantors at the front and rear of the assembly recite traditional verse. A common and popular selection is the retelling of the mythic origins of the reys. A number of young adult males then break away, and disappear into the darkness. Moments later they reemerge, flying at top speed toward the tribe from all directions. Mimicking an attack of ribbon serpents, they bathe the tribe in a torrent of disorienting ultrasound. The cantors respond by leading the community in a melodic chant, to hold it together against the confusing acoustic assault. All rey music is based on a 12-note scale, defined by their low-frequency auditory system. Eventually the "attackers" rejoin the group, and the chant morphs into a long, more complex sound poem.
          Somewhere between 450 and 470 kilurets depth, the reys regroup into V-shaped flying patterns. The tribal elders select a bearing, and the reys soar off in that direction. This marks the beginning of the third quad, which typically lasts another two and one-half yads. Normally, the reys fly back toward the plume / hot spring complex of the previous passage (with adjustments for jet streams and other intervening currents), recovering the distance crossed during the first quad in the opposite direction. They drop through the level occupied by the floating thickets, but generally eschew any contact.
          A tribe may seek out a new plume complex, if warranted by changing conditions. In particular, reys may abandon a complex that shows signs of failing. However, they then risk starvation, if a new feeding ground is not located in time. Microbe communities and thickets are less vulnerable to changes in the plume circulation. If a plume breaks up, microbes can become inactive spores, until they float into a supportive environment. Any nearby thickets simply stop growing; the thickets and their inhabitants subsist on food manufactured by the plants using the infrared flux from below, until they drift into or actively locate a new plume system. Once silicon and a more ample energy supply are again available, vigorous growth and reproduction can resume.
          The passage flattens out at depths approaching 565 kilurets, and the reys seek food near a modest hot spring, preferably a comfortable distance from the associated river of fire. The temperature here is a searing 555 nevlu (nearly 250° Celsius above the boiling point of water on Earth), higher than any other complex Jopian life form can tolerate, while the pressure is a crushing 675 rab (some 80 times sea-level pressure on Earth). The reys assume a flying formation similar to that of the community chorus, and must now be alert for ribbon serpents, which hunt in packs at the lowest levels. Young adult males serve as scouts, and also attempt to fight off serpents during an attack. Reys are equipped with a short, blunt, hardened rostrum at the prow end, used defensively to ram serpents. The rostrum tends to be better developed in males. When the reys locate a suitable upwelling, they skim the periphery, filtering manna microbes from the air.
          The fourth and final quad commences after feeding, as the reys seek out a current that will lift them into a water storm. Reys are adept at gauging the relative potentials of competing flows, and at judging the strength of a coming storm. Generally, the deeper they penetrate into the heart of a major plume, the more powerful the currents. Over the next ten yads, the reys ride the most promising winds upward, into the strong updrafts of a storm, and on to the hallowed summit of their passage.