Clade overview: Nienktvissen

The oceans of Eryobis are teeming with life, from worms that look like straight up aliens to scallops that decided they wanted to be fish.

Obviously there are also still vertebrates in the oceans in the form of fish and secondarily aquatic land vertebrates, but there is also another kind of "vertebrate" that lives in these oceans. Conodonts, while completely extinct on Earth for hundreds of millions of years, are still alive and thriving in the Eryobian seas.

Genetic testing suggests there were at least seven different conodont lineages to survive the mass extinction known as the World Scarring. 

As they always were, many of the still living conodonts are small, eel-like inconspicuous creatures. But there is one order that stands out, being among the most recognizable animals on Eryobis: the Teuthomorphichthyes. 

Better known as the nienktvissen, squidn'ts or "murder-molas", after one terrible incident, these conodonts are some of the most objectively easily identifiable creatures in the oceans. 

Nearly all of them swim not by undulating as most condonts would, but by flapping their very large dorsal and ventral fins, which were modified from the ancestral caudal fin. This gives them a style of swimming akin to the Molidae of Earth, which is ofcourse where the nickname "murder-mola" comes from. The majority of nienktvissen also possess from five to seven gill-slits and numerous long whiskers and tendrils near the mouth, which serve all kinds of purposes from feeding to steering.

Another common characteristic is their tooth elements which are often plate like and tend to stick out.

The hypothetical ancestor of the Nienktvissen

Nienktvissen are incredibly diverse and can be found in every ocean, sea and even in some freshwater habitats. They range in size from just a few centimeters long to gigantic oceanic cruisers like the lantern leviathan with its ten meter wingspan. There are even some forms which have evolved to live close to- and in the sediment, adapting to live on their sides like flounders and Planosolincolans. Unlike these true fish however, such nienktvissen have instead lost the eye that would permanently face down, essentially becoming cylcopean. 

Some examples of living nienktvissen

Despite their incredible diversity and richness in species, nienktvissen are notoriously difficult to classify among themselves. The terms "nienktvis" and "squidn't" were often interchangeable for early explorers, but recently it was established that squidn'ts are a type of nienktvis, specifically those within the Teuthomorphichthyidae, which are the true squidn'ts. But because of the interchangeability of the names in the early days of exploration, there is a lot of animals called "nienktvis" that should be classified as a "true squidn't" and vice verse a lot of "squidn'ts" that are outside Teutomorphichthyidae and are thus nienktvissen or "false squidn'ts". 

The fact that genetic testing has also yielded little result so far does not help with classifying them either. So while species and genera can be placed within families, those families can often not really be placed within a larger group.