Sunseeker Anatomy Overview
Eyes. Sunseekes have incredibly acute eyes with peanut or barbell shaped pupils. They are adapted to see clearly in both high and low light levels. Their scleras are gold, but are hidden the vast majority of the time. Only with extreme expressions do they show, often being described as "mad eye" - they are exaggerated for clarity in this illustration.
Mask. A Sunseeker's mask is incredibly similar to a Jellybug's mask. It is an owl-like funnel to the ears, and can flex to tune the hearing or express emotion.
Spiracles/airways. Sunseekers have extremely robust respiratory systems. They have 13 spiracles on each side for a total of 26 (see the others below). They have an elaborate series of air sacks and airways, rendering much of their bodies hollow and making them far lighter than expected for a creature of their size.
Arms. In addition to their 4 wings, Sunseekers also have 2 small arms. Their hands have 3 digits - 2 fingers and a thumb.
Wings & electroreceptors. Sunseekers' enormous wings are a striking feature of their anatomy. Their average wingspan is an astounding 56 feet (17 m). Their wings have 5 joints and are incredibly powerful. The lamella (see "Anatomical Details" below) on the outside tip of the wing are laden with tiny, near-invisible electroreceptors that allow Sunseekers to navigate in dense fog.
Feet. Sunseekers walk on their wings, each having 3 digits. On their forewings they have one digit on the third joint, similar to a Jellybug's sickle claw. This digit is webbed, and in flight acts like a bird's alula to prevent stalling and increase surface area. The other two digits meet the ground with the fourth joint and provide stabilization and grip while a Sunseeker walks or climbs. The 3 digits of the hindwings all meet the ground with the 4th digit. A tough lamellae-less callous forms on the section of wing that touches the ground while terrestrial.
Spade. The end of the tail is ossified to form a hard, pointed spade. This can come in a wide variety of shapes (see "Anatomical Details" below).
Blood. Jellybugs and Sunseekers share the same dark, blue-black blood.
Alternate View
Flight muscles. Sunseekers have enormous flight muscles on their backs, but especially on their bellies.
Wing slits. In both the fore and hindwings, there is a small slit down the middle of the ptagium. This allows air to more easily reach the spiracles while not in flight. During flight, microscopic velcro-like structures pin the two sections of wing together and prevent air from moving between them.
Spiracles. Sunseekers have 2 extra sets of spiracles under the wings.
Size
Height at shoulders: 12 ft (3.66 m)
Body length: 27 ft (8.23 m)
Wingspan (fore): 56 ft (17.1 m)
Wingspan (hind): 34 ft (10.4 m)
Weight: 1400-1550 lbs (635-703 kg)
Locomotion & Ambulation
In Flight
Sunseekers are long-distance fliers, with long, sturdy wings specialized for active soaring. The forewings provide most of the lift, and while the hindwings are crucial for gaining enough lift to fly, they are predominantly used for steering.
A healthy Sunseeker can fly for days on end, flapping so seldomly it often seems they don't need to at all. Despite their specialization as long-distance fliers, Sunseekers are surprisingly agile in flight, and their electroreceptors allow them to fly in close proximity and with great coordination in the right conditions. In clear skies their electroreception is dulled to the point of uselessness, but in fog Sunseekers have an almost supernatural ability to navigate around obstacles - and each other.
Modeled above: Sunseeker wings have 5 joints. The wing segments between are approximately the same length, except for the last two. The segment between the 4th and 5th joint is slightly longer than the others, and the final segment makes up nearly half the wing's entire length.
The mesoskeleton (see "Anatomical Details") does not extend the entire length of the wing. The bone in this section is only slightly longer than that of the segment between the 4th and 5th joints. The rest of the wing is flexible cartilage and lamellae.
Most are wary of a Sunseeker's claws and teeth, but their wings (especially while grounded) are their most dangerous natural weapon. A Sunseeker can "punch" with their wings hard enough to kill an adult human on impact. Luckily humans do not live in this galaxy.
Take-Off and Landing
Sunseekers do not take off with the same mechanics as birds. Their differing anatomy and size require Sunseekers to utilize their powerful flight muscles to get into the air. Sunseekers make a vaulting motion to launch themselves into the air, relying mostly on power from their forewings. The hindwings step forward to push off the ground simultaneously with the forewings.
A model of the motion of the wings as a Sunseeker takes flight, slowed for clarity.
This is a very intensive motion that requires a lot of strength and energy. So, many disabled Sunseekers are not able to take off from flat ground. Instead, these Sunseekers may be able to achieve flight by dropping off of tall structures.
Landing may be done a wide variety of ways depending on the situation. Most of the time, a Sunseeker lands by flaring all wings outward and pitching themselves vertically to rapidly decrease speed. This results in their hindwings being closest to the ground, so they often touch-down hindwing first. Also, touching down hindwing-first allows them to catch themselves with their forewings, whereas landing forewing-first usually results in them face-planting due to their momentum (a thing most fledglings learn the hard way).
Though, if one is careful, it is possible to successfully land forewing-first. Sunseekers are not normally able to hover, but may be able to hover in incredibly strong headwinds. This can allow them to get very close to the ground with little momentum, subsequently allowing them to easily drop out of the sky onto the ground. Otherwise, if they slow their momentum greatly and get close to the ground before landing, they can likewise drop onto their forelimbs with relative ease.
Sunseekers are also adept at landing on horizontal or sloped surfaces, often being able to match the angle of the slope while breaking and clinging onto the surface with their claws. This generally has the least impact on a Sunseeker's wings, so surfaces like this are often built for accessibility (and can also double as a high point to take off from).
Grounded
Sunseekers walk on their 4 wings, with a gait somewhat similar to a horse or deer (though usually much slower). While walking they are very steady and can stand for a fairly long time without getting tired thanks to the way their wing bones brace each other.
Sunseekers can gallop while on the ground, though only for short distances. Their typical top speed is around 14 mph (23 kph), but top athletes have been able to push to nearly 20 mph (32 kph).
Sunseekers are able to rear up onto their hindwings. Though, being somewhat top heavy, not all are able to balance on their hindwings, and even if they can balance they cannot maintain the posture for long.
Ambulation
Sunseekers have a pair of (relatively) small arms above their wings. These arms typically are not exceptionally strong, and are used for manipulating objects and preening.
The Sunseekers' distant ancestors once used these arms to catch aquatic prey by skimming. Technically a Sunseeker could do this as well, but their small claws and weaker arms would make it challenging and unsustainable.
The neck underneath the arms and much of the arms themselves are devoid of lamellae. This serves two primary purposes: the first being that this allows the arms to lay flat against the body and create minimal drag in flight. The second purpose is that it allows for easier heat exchange, as the lamellae are very insulating. A Sunseeker can thermoregulate based on the position of their arms, but also can keep their featherless young warm by holding them.
Mouth & Phototrophism
Sunseekers have fairly similar mouths to Jellybugs (see more details here), but do have some key differences.
Sunseeker mouths share many features with the Jellybugs', namely the crushing plate on the roof of the mouth, radula, chemoreceptors and teeth. Of these, the radula and teeth are most different.
The Sunseekers' radula differs from Jellybugs' in that it is long and flexible enough to extend out of the mouth. This also allows its sections to form a distinct forked silhouette, while the two sections of a Jellybug's radula sit next to each other and often give the appearance of one solid structure.
Sunseekers have large, sharp, triangular teeth which are specialized for grasping and shearing apart large sections of flesh. A tooth's sharp point also makes them adept at piercing thinner, flat sections of mesoskeleton.
As this unique dentition would suggest, Sunseekers are obligate carnivores, unlike the omnivorous Jellybugs.
In addition to eating (heterotrophism), Sunseekers are also able to acquire energy through autotrophic phototrophism. In plainer terms, they photosynthesize.
Fully bloomed Sunseeker wings.
The lamellae on the backs (and especially wings) of Sunseekers are equipped with rhodoplasts which allow them to photosynthesize. Usually, they are covered by specialized cells called shield shells that hide them from view. Shield shells are essentially just little sacks of pigment that cover the rhodoplasts. This allowed ancient Sunseekers to appear white or gray and remain camouflaged in the foggy skies of Hiluhea, at least while that was still a thing that was important for survival.
However, the rhodoplasts and shield cells can swap places, allowing the rhodoplasts to show - and more importantly, to photosynthesize. On a macroscopic scale, one doesn't see a single cell appear at a time. Instead, little spots will appear and then spread outward like ink bleeding through wet paper. This is called "blooming".
Sunseekers have very little conscious control over blooming. Sometimes they will bloom as a response to intense sunlight, in which the bloom generally sticks to the parts of the body exposed to the light. Artificial light can activate a bloom response as well, but often less effectively than sunlight. Sunseekers require specialized lights to get any sort of energy from artificial light. Other times, Sunseekers will bloom due to starvation, chronic stress or chronic sleep deprivation as their body tries every trick to survive. Stress blooming is often patchier, as the response triggers independently in different areas of the body and it spreads slower.
A Sunseeker cannot survive indefinitely off of photosynthesis, as it only provides energy, not nutrients. An adult Sunseeker may be able to survive off of photosynthesis for an extended time, but they will lose a significant amount of weight and their body will begin to degrade as it runs out of materials to replace its cells and essential nutrients. This is fully reversible with proper treatment. A Sunseeker who is still growing will suffer more greatly due to lack of food, and while they can become healthy again, their growth will be likely be stunted.
Anatomical Details
Individual variation in spades (left), and different types of lamella (right).
Lamellae
Sunseekers are covered in feather-like structures called lamellae (singular: lamella). These lightweight structures provide insulation, aid in aerodynamics, and defend against ectoparasites. The longest of a Sunseeker's lamellae can reach an astounding 10 feet (3 meters) long, but even then weight little more than 30 grams. The vast majority of lemellae are far smaller, and can weigh less than a gram. They typically lay in overlapping rows like fish scales, but can be displaced, requiring them to be groomed to maintain flight.
The lamellae are shed periodically to replace those that have been damaged. In theory, molting should follow a regular schedule, but in practice many variables affect a Sunseeker's molt and they can be unpredictable. In general, a Sunseeker undergoes a partial molt every Hiluhean year in the spring, usually shedding about 1/3rd of their lamellae. This follows a cyclical pattern, with one section of the wings following the other to ensure no wing lamellae ever gets older than 3 years. The body lamellae shed more sporadically, often in somewhat ridiculous-looking patches. The lamellae on the mask shed one by one, and so rarely form a gap. Depending on the lamella, it can take around 1-5 days for a single lamella to regrow.
Lamellae are connected to the circulatory system, but only through one tiny vein in the center. This allows for photosynthesis and keeps the lamella intact for longer. However, if a lamella becomes infected, it will automatically drop to prevent the infection from spreading.
Sunseekers produce a wax from a gland on their neck - right around where their hands rest. This wax is then spread onto the lamellae to keep them shiny, smooth, and waterproof. The wax fills any dents, divots, or small cuts in the lamellae, which allows a damaged lamella to be viable for flight for longer. Sunseekers are shockingly flexible, able to reach every part of their bodies with their tiny little arms to preen. This wax is very soft and putty-like when first applied, but will harden into a flexible veneer with exposure to oxygen and cold. In the modern era, this wax can be synthesized as well.
Internal Anatomy
A Sunseeker's internal anatomy is... fairly similar to a Jellybug's. For the most part. They both share a mesoskeleton and have similar healing and growth mechanisms, which you can read about on the Jellybug's Anatomy Guide.
Sunseekers have more soft spots than Jellybugs, their mesoskeleton covering less of their body. Notably, the wings only have bones along about 50% of the top edge, which are filled by airsacs. These airsacs serve many purposes: they are part of the respiratory system, they lighten the weight of the wings, and they act as pneumatics to increase the power of the wing.
However, the mesoskeleton on the chest and belly is incredibly sturdy, serving as an anchor point for powerful flight muscles.
The tail also has a spine of mesoskeleton running down the entire length - a thing Jellybugs do not have. Most of the tail is incredibly flexible, except for the tip where the segments of mesoskeleton get thicker and fuse together to form the spade.
Sunseekers have 4 hearts and 2 brains. A Sunseeker can live with one entire heart missing, but will suffer serious health issues because of it.
Individual Variation
A Sunseeker's spade grows in as a young adult well after they first fledge. It often takes years to stop growing, and in that time develops into a unique shape. Spades can have hooks, naturally cut-out sections, and spines. Since the ossification travels up the tail starting from the tip, sometimes spines can grow above the spade.
The shape of the lamellae have less individual variation to maintain efficient aerodynamics, but still vary to some degree between individuals. The shape of the lamellae themselves and how they lay can vary slightly. This causes some individuals to have especially sleek, scruffy, fluffy, or spiky silhouettes. The mask itself can also vary in shape slightly or have protrusions.
The most variation between Sunseekers is their coloration and markings. You can read about them below.
Coloration
Sunseekers can be white, black, and every gray in between. It is more common for them to be on the lighter side, but darkly colored Sunseekers are by no means rare.
Sunseekers can have a wide variety of markings. They tend to be countershaded, but aren't always. The inner edges of their wings are usually more darkly colored than the rest of them. Otherwise, it's a bit of a free-for-all. The following are some common markings:
Sable
Stripes
Speckling
Scalloped lamellae
Intricate or distinct markings on the mask
Colorpoint/inverted colorpoint
Mottling
High-contrast markings are fairly common, and usually seen as the prettiest by other Sunseekers.
Like Jellybugs, Sunseekers can erythric. However, this unique appearance is much rarer in Sunseekers and is caused by completely different conditions. Erythrism in Sunseekers is either caused by a lack of pigment or by malfunctioning shield cells - meaning that they cannot produce red pigments, but instead their rhodoplasts permanently show.
Without pigment the lamellae are pale and translucent, except where they have rhodoplasts. There, they are a stark dark red. Thus, Sunseekers without pigment have dark grey-blue bellies, ventral wing aspects, and tail tips - caused by their dark blood/skin. Their backs, faces, and dorsal wing aspects are bright red. This condition is extremely rare.
Sunseekers who have malfunctioning shield cells still have pigment, and thus can be white, grey, or black on their undersides. They only visual differ from Sunseekers with functioning shield cells in that their backs are permanently red.
Both of these conditions come with other complications.
Sunseekers can have blue and yellow eyes of varying shades, ranging from (for example) silvery near-white blue to navy. Blue-hued eyes are more common than yellow-hued eyes.
Reproduction
Like Jellybugs, Sunseekers are hermaphrodites. Unlike Jellybugs, Sunseekers do not have differing secondary sex characteristics.
Sunseekers lay eggs that develop independently of water, unlike Jellybugs. Also unlike Jellybugs, Sunseekers typically only lay 1-2 eggs at a time, and a single individual only lays a few times in their life - though in the modern era, most choose to only lay once or twice. Sunseekers have a fairly long incubation period of approximately half a Hiluhean year. When Sunseekers hatch they are small, bare of lamellae, sightless and mostly deaf.
In ancient times Sunseekers and their ancestors would bury their eggs while they were incubating to protect them from predation. So, even in modern times, when Sunseekers hatch they attempt to dig their way out of a nest that may or may not be present with an unparalleled determination. They only stop when they either feel the vibrations of their parents' thunderous voices, or exhaust themselves.
