Species Profile: Hagfisher

 Species Profile: Hagfisher

Abutting cloud jungles of the Flaming Mountains and golden steppes of central Yanhuo sits Lake Dazé, a geothermal reservoir around which wind unnavigable crutchtree mangroves. Here prowls cerulean placoderm relics, the only animals to cleave paths through the tangle. Eusocial peracarids assemble amphibious bone-forts from their remains, picked on by rajiform house centipedes, displacing fish in the seething waters. Mite spin webs in the canopies to ensnare small shantaks. Countless others slink through the endless gullets: flesh-bearded tiehe, mantis storks, pacers, castverms and hermites, acanthodians, tetragnath fish, jetleeches, and others which fail to fall into our parochial classification. Dazé's perplexive alure is well aknowledged, every expedition bringing attention to new taxa as ancient as peculiar. But there are some which venture beyond even the unconventional strangeness of Dazé into inexplicablibility, the zenith of which is the fishing cryptid.

We saw it in a mad stroke of luck on our first expedition. The day was as customary as could be until Iosua noted a nearby splash at dusk, turning to be faced with a four-legged creature scampering into the clearing with a freshly caught jetleech in its clasps. It had no visible armour, shrouded under a pelt of greenish fuzz. Two beady eyes mounted its snout like a pair of search lights, under which hung two sets of arms it used to make short work of its unfortunate annelid prey. To a Dome 4 researcher, it might as well have been an alien; how could it be possible for a placoderm to have eight limbs, and if not a placoderm, what else could it be? I would have accused him of fabricating tales if not for the fact I saw it too. Our net guns had run out of ammunition, generating regretful pleas and wails against the logistics officer. As the team debated, the cryptid slid away. We returned to the clearing every day in spare time until our assignment changed from Dazé to southwestern Yanhuo. Yet obsession yielded nothing. We were left to watch ponds disturbed only by fizzling bubbles and jetleeches swimming without worry.

Our team was not the first to discovery the fishing cryptid. Records from the first teams sent into Dome 4 described a similar nocturnal enigma by the foot of the Flaming Mountains. No samples were ever taken, but theories for its origin ranged from ultra-basal thriae relatives, to arthropods covered in algae, to a simple trick of diffraction. Most outlandish but strangely credible was the assersion that the animal was not a Dome 4 native, but traced its origins to the sixth dome, a place now sealed behind a wall of ice and atrial oceans. Its limb count did vaguely match that of some terrestrial hagfish, but it would take a madman to believe that they could cross the sub-6 decks, both flooded and frigid.

It would not be many months until we returned to the lake, now in the company of a recent transfer from Dome 6, Satya. Ever since I had told them of the fishing cryptid, Satya was convicted of the hagfish hypothesis, especially as recent reports in Dome 5 eluded to the range of myxini being wider than first thought. As if by providence, we saw the cryptid once more in broad daylight, absent-mindedly following a thria. Netted, tranquilized, examined, and dissected, it vindicated this most unlikely theory.

Anatomy and Relationships

The hagfisher (Bdelliphagus dazeensis), as Satya has taken to call it, is the first terrestrial hagfish to be discovered in Dome 4, and just like the Rhynian hagfish in Dome 6, are as anatomically disparate to the hagfish on earth as we are to Haikouichthys.

The body of a hagfisher is roughly divisible into a cephalothorax, abdomen, and tail. The cephalothorax houses the eyes, nostril, tentacles, and front four limbs of the animal. Seperated from the skull, the eyes rotate on a pseudo-stalk, capable of moving independantly for 360 degrees of vision. This is possibly an adaptation to cope with the animal's lack of a neck, as the cartilage of the skull is firmly linked with ossicles and chords in the rest of the cephalothorax; similar adaptations are found in pleccles and shovelpaws. Typical of any piscivorous animal, the singular nostril inhereted from its hagfish ancestors is located high in the snout to prevent it being waterlogged. Despite its use in smell in tetrapods and bipods, the nostril of the hagfisher seems to have a solely pneumatic function, pumping air into the animal's accordion-like lungs which are then blown out a series of spiracles at the flank. Olfacation has been outsourced to the tentacles, densely lined with both mechanoreceptors and chemoreceptors, once again typical of Earth hagfish. The mouth is located under the head, opening horizontally and flanked by a pair of tentacle-derived pedipalps. Lined with keratinous teeth, the hagfisher's jaw is most likely homologous to the dental plate, a radula-like structure that everts and retracts to rip chunks off carcasses in their ancestors. The arms of the hagfisher, though soft and endoskeletally supported, are bereft of digits, instead adorned by spikes derived from filaments. Though without a neck, hagfishers can rotate their cephalothoraxes up to 45 degrees, owing to a muscular hump also responsible for energetic outbursts in diving.

The abdomen houses the bulk of the hagfisher's digestive system and two pairs of walking limbs. Upon opening its stomach, we were greeted by the stench of fish, leeches, and centipedes. Curiously, the centipedes were barely masticated compared to the stomach contents of other arthropod eating lakeside residents, such as reedstalkers or marsh cacklers. When poked with a scalpel, however, their exoskeletons seemed to be entirely absent, letting the blade slide through without any resistence. This possibly eludes to the evolution of chitinases or at least associating with chitinase producing gut flora, though the eaten centipede could just be moulting. A crop was identified before the gut as well, holding what seemed to be semi-digested food. Later field studies found feeding behavior by mother hagfishers to their young in riverside nests through regurgitation, suggesting the purpose of this organ.

Discovering the hagfisher raised more questions than it answered. Satya tells us that the anatomy, though thoroughly convincing as a hagfish, is unlike anything they have met while working in the wall forests of Dome 6. The animal had too many limbs to be a hedraoran, but too few to be a vilgintipede. Its poise had a passing resemblance to slothhags, but they are an equally enigmatic clade themselves, descending from a ghost lineage of bygone fliers. The hagfish discovered thus far in the decks and other domes had all been recent colonizers of air from the atrial ocean under Dome 6.

For years, myxini scholars and station physicists had agreed that Dome 6 was sealed by water not long after the precursors' departure. The discovery of the hagfisher forces us to re-examine this interpretation. The hagfisher could not possibly have been a descendant of direct water-to-deck colonizers. Despite its strange anatomy, it had complex eyes which, according to Satya, were homologous to that of ptychopinnid hagfish, a diverse clade with arboreal, terrestrial, and aquatic descendants in Dome 6. Eyes in the sub-6 decks would be a nonsense adaptation, and considering how many millions of years it would have needed to stay there before reaching Dome 4, I do not buy avatism or convergence as satisfactory explanations. Could it be that Dome 6 was only flooded recently, and that the hagfisher's ancestors came into the lighted decks, then Dome 4, when it was dry? Upon further inspection, some of the aerial fauna we caught in our second expedition turned out to be hagfish as well, not thriae. Specifically, they were votemis, the most prolific hagfish by far in the modern era. If the hagfisher was a fluke, then what of them? It would not be the first time a proposal as radical as this turned out to be correct; the consensus on Dome 2 a few years ago was that it emulated the living conditions of the precursors' homeworld.