| Crawler | |||
|---|---|---|---|
| |||
| General Information | |||
| Universe | Kyklos Mythos | ||
| Classification | Dispinopisthos minor | ||
| Species Type | Xenosuran | ||
| Homeworld | Vuunega | ||
| Environment | Zeeon: Southern Beach | ||
| Intelligence | Non-sapient | ||
| Biochemistry | Carbon-based lifeform | ||
| Biological Information | |||
| Reproduction | Sexual; lays eggs | ||
| Locomotion | Benthic crawling | ||
| Feeding Behavior | Carnivorous | ||
| Prey | |||
| Predators | |||
| Skin Color | Brown | ||
| Lineage Information | |||
| Cultural Information | |||
| Alignment | True Neutral | ||
| Personality | Mindless forager | ||
| Organization | Solitary, though have no territoriality so can appear in swarms | ||
| Sociocultral characteristics | |||
| Scientific Taxonomy | |||
| Planet | Vuunega | ||
| Domain | Monocentralis (Single-Nucleus Complex Organisms) | ||
| Kingdom | Neovuumalia (Neovuumalids — The New Vuunegan Fauna) | ||
| Subkingdom | Zygodermata ("Joined Skin") (Neovuumalids with 3 Germ Layers) | ||
| Superphylum | Exuviazoa ("Exuvia Life") (Zygodermatans who produce exuviae) | ||
| Phylum | Arthrophysis ("Jointed Form") (Arthrophysids — Descendants of the Roundvorms) | ||
| Subphylum | Duodecimopoda ("Twelve Foot") (Twelve-legged Arthrophysids) | ||
| Class | Pelagomorph ("Open Ocean Shape") (Marine Duodecimopods & their descendants) | ||
| Subclass | Archaeopteryxia ("Ancient Fin") (Ancient Swimming — & their descendants) | ||
| Order | Xenosura (Xenosurans — Benthic Archaeopteryxes) | ||
| Suborder | Carnostoma ("Flesh Mouth") (Carnivorous Xenosurans) | ||
| Family | Zandistomia ("Sand Mouth") (Coastal Crawlers) | ||
| Subfamily | Zeeonia (Zeeonese Coastal Crawlers) | ||
| Genus | Dispinopisthos ("Two Thorns At The Back") (Dual-pronged caudal spines) | ||
| Species | minor ("Smaller") (Smallest of the Dispinopisthoses) | ||
| Other Information | |||
| Status | Least Concern | ||
| Creator | Somarinoa | ||
The crawler (Dispinopisthos minor) is a prime example of the xenosuran line. Once preyed upon by the now-extinct Therox, an ancestor to the Aurix and Aurosuchus lines.
Physiology[]
As a species, Crawlers are cold-blooded amphibious xenosurans found along the southern coastlines of the continent of Zeeon on the planet Vuunega, as well as in the tropical to sub-tropical shallow seas off these coasts, with the exception of within koryl reefs. They prefer sandy or sedimentary bottoms in order to burrow themselves into them. Crawlers are not built for manipulating objects much, as the only thing they really need to manipulate is sand for laying eggs in and digging for prey, which they do so by utilizing their multi-purpose jointed fins.
In their own defense, they will wield their dual-pronged caudal spine, which is armed with a minor poison. This may cause disorientation in opponents, which gives that creatures' predators a better chance at bringing it down. This caudal spine can also be used to flip the Crawler back over should it flip onto its back. If held, they may resort to pinching with their foot-claws or biting.
While their caudal spine is their major line of attack for predators of their own, Crawlers will typically only use one of two weapons against their own prey: either their foot-claws or their mouths. Because their prey is significantly smaller than them usually and does not possess a backbone, they are usually easily taken down and killed with little effort.
Exoskeleton[]
Crawlers possess a tough outer exoskeletal shell which they utilize to defend themselves from attacks that might kill them. This shell is shed regularly however for them to grow, and for a few hours at a time they must avoid danger at all costs until their exoskeleton hardens once more. This armor is not successful against significantly heavier creatures, which can easily crush it, thereby instantly disabling, crippling, or outright killing the creature with a sickening crunch.
Brain & Nerve Center[]
The brain of the species is relatively large and fill the majority of the head section of the body. Their nerves are deadened within the carapace although they can feel if they are being touched.
Respiratory System[]
Crawlers, like other Xenosurans, breathe through organs known as lungills. Lungills operate by pulling water into the basin-like organ where undulating gill structures pass the water along through the ducts exiting out on the other end. However, by allowing the basin to fill with water and then using muscle contractions in the organ itself to constrict the ducts and seal them off, the Crawler can effectively breathe on land for some days before the water in their lungill will begin to reach depletion levels and they will need to refill. The lung can manually be squeezed by outlying muscles surrounding it to allow water to rush out of the ducts, thus allowing them to more quickly take new water in while also giving them a quick water jet burst if necessary.
Circulatory System[]
While the heart itself as well as the veins are relatively unremarkable, the blood is of note. Unlike many species, xenosuran blood is copper-based, and therefore appears blue when oxygenated.
Immune System[]
The immune system of the Crawlers is a remarkable one. With a complete lack of white blood cells, their immunities actually occur from inside their blue blood cells themselves. When a blue blood cell detects that it has become infected with a virus, it will sacrifice itself, bursting open and releasing antibiotic enzymes that break down the virus or bacteria. Because of this, few Crawlers ever get sick for long, and far fewer die from their malaise.
Senses[]
Xenosurans rely on their eyes as their primary means of perceiving their environment. Their eyes are compound in nature and placed at the top of the head segment but before the overlapping crest that helps protect the connective tissue between the head and thorax. They do not have a sense of smell and their sense of touch is limited, though allows them to feel anything that comes in contact with their body. To hunt, they use low-frequency electroreception using ampullae of lorenzini pits along the edges of their carapace to detect benthic lifeforms suited for consumption buried beneath the oceanic substrate. Upon taking a creature into their mouth, taste will inform them if they are actually edible or if they're poisonous and needed to be spit out.
Hearing is a sense usable at all times for detecting potential predators seeking them out but is primarily used during their mating rituals, in order to hear the swishing of a suitor's caudal fin. Magnetoception is their final sense and allows mated pairs to return to the beaches of Zeeon.
Social Behavior[]
Dietary habits[]
Crawlers are semi-social predatory insectivores. They hunt for their food 100% of the time with a 10% average success rate. When feeding, they use their antennae to sense vibrations under the sand; once potential prey is located the process of digging it out through the use of the jointed fins begins, aided somewhat by the foot-claws. Once enough of the prey item is dug out it is grasped by the foot-claws and wrestled into the mouth, which provides the kill. With the creature dead, the Crawler sets itself down to rest on its carapace and chunks are clipped off by the foot-claws which then feed the bits to the mouth. The mouth chews up the small portions and swallows it, delivering it to the fore-gut, which holds the food for a short amount of time before passing it on the the mid-gut. The mid-gut provides most of the breaking down of the matter and then passes it into the epigaster, where the rest of digestion takes place. Waste remnants are excreted out of the anus on the other end, but only in water, which will wash it away or at the very least dilute it.
Reproduction[]
Crawlers reach sexual maturity reached after 2 Vuunegan years (~3.424 Earth years) and will reproduce during a short, four-week period during the spring months. They will enter a state of estrus and a prolonged mating ritual will occur. Males will burrow halfway into the local sediment equal distances apart while the females will come and inspect them. Males will attempt to keep face-to-face with the female while both swish their caudal spine up and down. Should their sounds match and should the male properly continue to face the female's movements around him, the two may accept one another as mates. At this point the male will unbury himself and climb atop the female's carapace and piggyback all the way to the beach. This journey may take about a week depending upon how far from shore the individual pairings were, which matches up with the female's 1 week internal gestation period.
Should the pair arrive at the beach early, they will hang around until gestation has fully occurred before proceeding. At this point the pair will crawl up upon the shore during the night in droves of hundreds of thousands of individuals where they will officially begin their mating procedures. During this time many will be predated upon by local predators who will sense this period of time and will wait for their arrival, but their numbers prevent them from being properly threatened by this event. The females will dig a hole and way 100,000 gelatinous eggs into it as her clutch and will remain covering it to prevent dehydration. During this period, if a male has lost his mate he may forcibly try to take the mate of another rival male by initiating the mating procedure's caudal spine moves; the other male may case them off or the female may accept the new male instead.
Upon proper fertilization the female uses her jointed fins to gather the eggs again, at which point they are held under their overarching carapace for 3 weeks until they hatch. At this point they are on their own and must fend for themselves. For this reason only 0.0001% will actually survive to maturity — out of each clutch, only about 10 will make it to their first estrus. Even so, millions still survive to maturity to breed on beaches covering Zeeon.
Life Cycle[]
Crawler young start life encased in unfertilized gelatinous eggs laid into the moist beach sand of the tropical and sub-tropical coastal beaches of the Zeeon continent. Upon being fertilized the outer layer of the egg immediately starts to harden and the female will scoop up the eggs and apply them with her legs to the inner layer of her thoracic carapace where the hardening procedure will cement them to the shell. The larvae will then develop within over the next three Vuunegan weeks (630 Earth hours or 26.25 Earth days). These then hatch into their first larval state, referred to in Xenosurans as a yolker.
Yolkers are microscopic at first, with the body being only a few cells across and most of the form consisting of a large yolk sac. The yolkers will keep themselves safe by continuing to hide underneath their mother's carapace while they continue to mature. As they get larger and larger between moults the yolk sac will diminish and less and less space will be available for so many young. Eventually they will begin to get pushed out from underneath the carapace into the dangerous world beyond. Nearly all of these that are pushed out early will perish before reaching maturity. After several moults the yolk will be fully consumed with a final moult that will lead into the next larval stage, the nauplius.
The nauplius stage of a crawler's life allows them to begin moving on their own, through the use of enlarged antennae to propel them short distances in the water. By this point they are barely noticeable to the naked human eye and will begin to seek leaving the safety of the carapace as they now must feed themselves in order to continue to survive. A common practice is for these larvae to locate various dia mats to feed upon and take shelter around, although in some locations they will hide amongst vuukelp leaves more often instead. They will continue to moult over time and grow larger and heavier. Eventually a set of appendages will begin to appear and take over for the antennae as the larva will have gotten too heavy for their antennae to really help move them along. At this point they will reach the third larval stage, the zoea.
Zoea in crawlers start out rounded, now using their exposed gill-appendages for swimming and their antennae and legs to control their movements in the water; a long spine will act as a rudder and help keep them upright in the water column. Crawler zoea are large enough to see with the naked eye, though still quite small and thanks to being transparent are sometimes hard to notice as they inadvertently camouflage to their environment. At first, the antennae and legs will end in "hairy" tips covered in setae to help catch the water around them for better control while their gill-appendages rapidly beat to push them forward. As they age these gill-appendages will learn how to pull them in reverse and the rudder-spine will slowly shrink throughout moults, the excess exoskeleton material being used to make the creature wider. It will widen laterally into a hydroplane surface at first which will help them glide along before curving upwards into a rudimentary version of the adult's carapace. As they grow larger and heavier they will spend their lives lower in the water column until the late stages of zoea life, where they will spend almost all of their time surfing along the sea floor, though they can still swim at this stage of development. Their final moult from this stage will put them into the juvenile stage.
As juveniles, crawlers will look more or less like their adult counterparts, though with a more laterally-compressed and less domed look to their carapace and larger jointed fins in comparison (though in truth the jointed fins stay the same size while the body grows around them). They will only leave the sea floor to escape predators. Further moults will grow out their caudal spine and add poison glands at its tip to help deter would-be predators. As they reach later stages and near maturation their jointed fins will become insufficient to keep them off the sea bed and they will become bound to the ground, as it were.
Evolutionary History[]
A Crawler, Dispinopisthos minor.
Crawlers are the sterotypical xenosuran: when one thinks of a xenosuran, it is usually they that comes to mind. They are ancient, living fossils who have barely changed at all in many millions of years. However, according to Aurixan paleontologists such as Dr. Dvodia, this was not always the case.
A marine seabed crawler for several millions of years, they came to land.