Ægiric Ubondo

Some people in the imperium have referred to Eryobis as "a fisherman's paradise". Compared to Earth and the countless colonies of the imperium, Eryobis has a particularly high amount of very large marine creatures that make for great sport fishing. The kicker is, the local goverment of the AnVela Koeliv system encourages sport fishers to come to Eryobis to help document the incredible diversity of marine life that this world possesses. 

A very large portion of the marine biologists currently deployed on Eryobis are indeed just fishermen who take their job seriously.

 As such, a lot of newly found marine creatures also get their names from the fishermen that catch them. While they often call in actual biologists for the binominal names, they tend to give their fish common names with sometimes unclear origins, sometimes derived from their own languages, sometimes from what the native Eryobians call them or something else entirely.

In the case of the Ægiric ubondo (Ubondo aegiricus),  it was named not for any of the above mentioned reasons, but was rather named by the fisherman that first caught it, Agner Ubondo, and named it after himself. At first they called it "Ubondo's fish", but it quickly changed to just "ubondo"  for simplicity's sake.

The Ægiric ubondo grows to around 1.5 meters in length and is a powerfully built pelagic fish with a very large tail fin. While it may not immediately look like one, the ubondo is in fact a kind of bunnyfish, as can be determined by the placement of its pectoral- and pelvic fins. But while a lot of bunnyfish have evolved somewhat shark-like features, the ubondo has evolved to look more like a tuna, with a torpedo shaped body and small front fins. DNA analysis has shown that ubondos are most closely related to the deep sea fish known as gladdos and together they seem to form their own branch at the base of the Odontocoeiida.

Ubondos usually swim between 0 and 70 meters below the surface where they feed on other and typically smaller pelagic fish, as well as llamplelgans and pectinauts.

While most of their teeth are rather small and concealed by their lips, they possess 4 large fangs at the tips of their jaws that are probably used in prey capture, but might also be used for interspecific combat during mating season.

Red-eye Prosse

Toeing the line between camouflage and extravagant display, the red-eye prosse (Ithopoius coccineus) is a curious little bunnyfish that inhabits seaweed forests off coastal Lachoba. The most striking feature of prosses are their enormous pectoral- and pelvic fins that are normally held against the body, but can be folded out for display. These four large fins have colorations and markings resembling large, red eyes.

These fins are used for both attracting mates and to intimidate competitors and predators. As typically solitary animals, prosses carve out little territories for themselves and do not seem to tolerate other prosses of the same sexe within their territory, but these territories do often overlap with those of the opposite sexe.

Red-eye prosses feed mostly on small invertebrates like various annelids, small arthropods and pectinauts. One thing that has been observed by scuba divers is that prosses will approach divers within their territory and search them for parasites, which might indicate that they act as cleaners for larger animals when they stop by.

Despite possessing no teeth, genetic testing has revealed that prosses are most closely related to the Odontocoeiida, the toothed coeaaien, more than any other bunnyfish. This further reinforces that the shark like body shape of various coeaaien evolved independently.

Black Gladdo

The deep sea of Eryobis is a large and scarcely studied habitat, yet it is also likely one of the most biodiverse. ROV expdeditions and deep sea fishing by both researchers and natives continuously bring up extraordinary and strange animals.

When one goes deep sea fishing in the Vyaris Ocean, a fish that is often caught at mesopelagic depths is the black gladdo (Eryobalepus atratus). This up to 40cm long deep sea bunnyfish seems to be quite common in these deep tropical waters. Stomach contents of these fish have revealed that they are not picky eaters and will feed on whatever they think they can fit in their mouths, which seem to be able to open up very widely and can expand to twice the width of the head.

The phylogenetic placement of gladdos is a bit unclear, as they possess a mixture of primitive and derived traits and have therefore been placed in their own branch on the family tree.

Dacruon bathynectes

The Voûlic Ocean located near- and on the south pole of Eryobis has, on average, the coldest waters in the world. Even though barely any permanent sea ice exists, surface temperatures are known to drop below 0°C in winter. The cold waters of the Voûlic however, are also very oxygen- and nutrient rich, resulting in the south polar ocean being some of the most productive waters on Eryobis. Many peculiar organisms can be found in the chilly depths at the southern end of the world, with some more rare than others. 

The waters are often too cold and potentially dangerous for human explorers to dive into, so ROVs are typically employed on expeditions here. ROVs often only ever encounter small invertebrates or small fish too slow to flee from the lights, but on occasion, the ROV may encounter something more rare.

On one such encounter, the ROV came across a kind of fish that had never been seen or heard of. Measuring between 3 and 4 meters long and shaped like long tailed tear drop, the Dacruon bathynectes, still lacking a common name, is very large kind of bunnyfish, as could be determined by the placement of its pectoral- and pelvic fins. 

The enormous fish was found at a depth of around 300 meters, just below the photic zone, slowly cruising with long movements of its tail. Because the fish moved so sluggishly, the ROV was able to place a tracker on its dorsal fin, which revealed that D. bathynectes performed vertical migration; spending the day time hours at depths between 200 and 500 meters and moving up around 30 meters deep during the night.

Footage of the fish's head revealed that it large, flat and blunt teeth within its thick, but deep jaws. This points to D. bathynectes being a durophage, feeding on hard shelled prey like mollusks and crustaceans. While no footage of the act of feeding, or evidence from washed up specimens exist, it is thought that Dacruon most likely relies on pelagic pectinauts as its main food source. The slow swimming nectonic scallops are known to perform vertical migration in other parts of the world's oceans, so it is not unreasonable to assume they might do the same in the cold waters of the Voûlic.

Red Aetchna

Despite Lachoba being located quite close to Guralta, it seems the freshwater systems of Lachoba have been mostly isolated from Guraltan freshwater for a very long time. Because of this one can find some peculiar fish swimming between the vegetation in the murky rivers and lakes of Lachoba. Just one example of this is a particularly archaic bunnyfish that has likely been living here since long before Lachoba became an island continent.

The red aetchna (Lagesox rubicundus) is one of several species of somewhat pike like bunnyfish living in Lachoba. The name "aetchna" is, like many other names we use to designate animals on Eryobis, borrowed from a word that the natives use for it. 

These fish grow to about a meter in length and are known to be vicious and aggressive. With multiple rows of sharp, recurved teeth, an aetchna does not let go once it has bitten into its prey. Since their teeth are not serrated, they often fiercely thrash around to rip chunks of flesh off if their prey is not small enough to swallow whole.

Typically solitary and not particularly opposed to cannibalism, aetchna's are known to try to feed on pretty much anything that moves. This makes them a great target for native fishing efforts as they are quite easy to catch. It is said that their meat is toxic unless smoked, but studies are yet to confirm or deny this.

Aetchna's and a few other archaic bunnyfish were at first thought to be related to the Odontocoeiida (the toothed coeaaien), based on a number of physical characteristics. Recent genetic studies have shown however, that aetchna's are not only unrelated to toothed coeaaien, but that they in fact predate the majority of other living bunnyfish and are likely to have split off between 100 and 110 million years ago, somewhere in the early Anaktisian. Whether they have always lived exclusively in Lachoba or if this is their last stronghold remains unknown as of now.

Clade overview: Coeaaien and Bunnyfish

Some of the earliest reports from explorers mentioned the presence of sharks in Eryobian waters. 

Knowing that Eryobis is world where all its life has a terran origin, this mention of sharks was initially overlooked and shrugged off as a quite likely plausibility, given the incredible age of Elasmobranchs.

However, when footage of these supposed Eryobian sharks was properly examined, something about them immediately seemed off.

They did not have the 5 to 7 gill slits typically associated with sharks, instead possessing an operculum and thus only one gill opening.

They appeared to have no pelvic fins at all, their first dorsal fin looked as if it was laterally split in two and the caudal fin, while heterocercal like a shark's, appeared to have three distinct lobes.

Those among the explorers with knowledge of terran paleontology suggested that these creatures could be Holocephalians, related to the chimaera's of Earth. For quite some time, this was considered to be the most likely origin of these "sharks", since it technically fitted within the suggested Eryobian evolutionary timeline.

As specimens were examined up close and subjected to testing however, the idea that these were even Chondrichthyians at all was quickly discarded.

In pretty much all genetic tests, they came out as being closest related to the coelacanths and more specifically, with their closest relatives being the Anisospondyls. 

When more fossils of prehistoric Eryobian fish were unearthed, the pieces fell into their place.

These were no sharks, they were Lagotoichthyiiformes or rather, bunnyfish.

Their close relation to the Anisospondyls now made sense, for these now land dwelling creatures are Planosolincolans and thus technically bunnyfish themselves.

The "dorsal fin split in two" are actually the pectoral fins which had shifted far up the body to act as dorsal fins and what seemed to be the pectoral fins are actually the pelvic fins that moved far to the front of the body, as is seen in all bunnyfish.

Reconstruction of Lagoselache durus, the likely ancestor all coeaaien and kin

It seems that bunnyfish were hit extremely hard in the mass extinction known as the World Scarring, with most genetic evidence suggesting all modern forms can be traced to a single ancestor that lived around 120 million Eryobian years ago.

In fact, a likely candidate for this supposed ancestor has actually been found in rocks dating to the early Thyellian: a small fish named Lagoselache durus. 

This fish shows the characteristic "double dorsal fins" and three lobed heterocercal caudal fin, demonstrating that this condition was ancestral to all modern forms.

 

Some examples of living coeaaien and kin

At some point, the term "coeaai" (pronounced "koo-aye") became widely used among explorers to refer to the more shark like bunnyfish, likely a contraption of coelacanth and the ancient dutch word for shark "haai". 

All the modern bunnyfish have been classified as supergroup named Lagoselachia, after the oldest known member. Despite this name, not nearly all of them look shark-like. And apparently some of the most shark-like members of this group evolved largely independently. A good example of this are the toothed coeaaien and the plated coeaaien. Both of these look very much like sharks and resemble each other quite a bit in overall anatomy, yet genetic testing suggests these split over 80 million years ago and both have many relatives that do not look particularly shark-like.

Then ofcourse there are also Lagoselachians that surrendered their ancestral body shape for that of a more typical bony fish or even turned it into something else entirely.

The modern bunnyfish and coeaaien are very diverse in body shape, yet they are not very numerous in species compared some other Eryobian fish orders. Still, they are not an uncommon sight in any Eryobian waters and often fill critical parts of the ecosystem they find themselves in.

Evolution of the Flattacanths (Planosolincolae)

At some point in the Asthatian period, most likely during the late Agonian stage, Mawsoniid coelacanths of the order Lagotoichthyiiformes (bunnyfish) began adapting to a more benthic lifestyle. 

But, instead of becoming dorsoventrally flattened as most fish would, these already laterally flattened Lagotoichtyiiforms would instead evolve for life on the seafloor in a different way. Akin to the Pleuronectiformes of old Earth, these bunnyfish went through a cranial metamorphosis that saw one of their eyes migrate to the other side. This allowed them to skillfully lay flat on their sides on the sediment, becoming "flattacanths". 

These "flattacanths" became the order Planosolincolae, and rapidly spread around the world as they faced very little competition in this new niche they created for themselves.

Initially they kept to shallow coastal waters and stuck to their niche. But soon they would expand into deeper waters and would even start leaving the seafloor to pursue more mobile prey.

Eventually, Planosolincoles would venture into freshwater ecosystems and start exploring habitats outside the water. This would give rise to the most diverse group of flattacanths today: the terrestrial Anisospondyli. 

Assorted fossil coelacanths II

The species pictured above would’ve lived between 26 and 40 million years P.I (Post Introduction) and some of them would’ve coexisted with each other.

1. Not a Bunnyfish, but a late representative of the family Brachysomatidae. This laterally compressed reef fish perfectly demonstrates how the pelvic fins were pushed forward to the skull as a result of their disc shaped bodies. The classic Brachysomatids continued to thrive until their ultimate replacement as dominant reef fish by their Bunnyfish around 33 million P.I. by their Bunnyfish relatives.

2. Since the anoxic event of 25 million P.I. sterilised killed many of the fish that inhabited the early reefs, the Brachysomatids were able diversify and take on new shapes. The Percimorphines were a successful, although short lived, subfamily of Brachysomatids. Their bodies elongated and as a result, they started resembling perch-like fish. In general, they were small to medium sized reef fish that fed mostly on gastropods and crustaceans. Their reign was short, for they were quickly replaced when a family of Holosteans also began to occupy the reefs again.

3. Among those that escaped was the Proto-Bunnyfish, a Percimorphine that had high placed pectoral fins that were most likely used for some sort of display. It escaped by living in estuaries where it hunted smaller fish, biding its time to return to the reefs of its ancestors.

4. In 31 million P.I. the first of the Lagotoichthyiiforms appear, the true Bunnyfish. They are named for their pectoral fins which are placed near the very top their bodies right behind the head, resembling bunny ears. In basal species, these fins are most often used for visual display, either to attract a mate or to warn or confuse predators. Often these fins have vaguely eye-shaped spots on their pectoral fins and sometimes even mouths and teeth shaped patterns on their heads. Bunnyfish became very successful and diverse very quickly and remained successful for a very long time, even surviving to modern times. Exactly what the reason behind their succes is, is unknown, but it might have been their more advanced brains that evolved as a result of their displays.

5. Once the Bunnyfish made their way into the open ocean, they faced a lot of fierce and fast predators. Some adapted by becoming very fast swimmers, while others took to the sky. By evolving their high placed pectoral fins into wing like forms, the “Wingacanths” were able to escape the their assailants from the deep by gliding through the air. Peculiar among this group was the hypertrophied anal fins present in males that served as intromittent organ.

6. While the many non-disc shaped Brachysomatids had already been driven off by newer Holostean competitors, the classic disc shaped species still survived for a while. That was until a new kind of reef fish started appearing. Being more advanced than their Brachysomatid relatives, the new Bucktoothfish quickly outcompeted and replaces them, becoming the dominant reef fish of the second epoch.

7. But Bucktoothfish were not the only Lagotoichthyiforms to invade the reefs once again. Back in their estuary birth grounds, a early Bunnyfish offshoot picked up a taste for hard foods, most notably cyclid crustaceans. For this they developed broad, flat teeth for crushing the carapaces of their prey. When they spread to the reefs, they became more sluggish and adapted to spending large amounts of time on the bottom and as a result, evolved wide pelvic fins to hold onto rocks. But their slow moving lifestyle also made them more vulnerable. In response to this, they developed sharp spines coated in toxic mucus with bright colours to warn any potential threats.

8. Some of the early Lagoichthyiforms became sleek predators with flattened laterally compressed bodies. They hunted in a wide range of habitats; from coastal reefs to the open ocean. Among them were also those that hunted near sandy bottoms and meadows. Mostly preying on small animals buried in the sand, they developed a peculiar hunting style by swimming on their sides to better get close to their hidden prey. It is among the ranks of these specialised predators, that in 43 million P.I. the first Flattacanths arise.

9. The same lineage of Bunnyfish that lead to Flattacanths also lead to group of eel-like Lagotoichthyiforms called Dracanguilids. With long, ribbon like fins and a serpentine body, they remind of oriental dragons. These fish are mostly nocturnal hunters of the reefs and can reach some impressive sizes. As with many other Bunnyfish, their fins re used for display, but instead of sexual or threatening display, they use theirs to hypnotise and stun their prey items by letting their fins dance around.