Eel monsters

Eel monsters are ill-studied animals for a number of reasons. With laboratory studies being nearly impossible, most of this information comes from observation. Even then, their reclusiveness means there is still much about these animals that remains unknown.


Eel form

Eel monsters resemble large moray eels with legs. They come in a wide range of phenotypic morphs that appear to correspond to moray eel species. Their limbs are short relative to their body length, giving them a body plan similar to weasels, ferrets, or other long mustelids. The feet have 4 toes and pads that allow them to grip surfaces.

Height at the withers can range from about 2.4 meters (8 feet) at the extreme lower end to 10 meters (33 feet) at the extreme upper end. Length from snout to tail ranges from about 16 meters (52 feet) to 57 meters (187 feet). However, extremely large and small individuals are relatively rare. The majority of individuals have heights ranging from 4 meters (13 feet) to 6.5 meters (21 feet) and lengths ranging from 25 meters (82 feet) to 40 meters (131 feet).

The eyes are small with slit pupils. They have excellent vision, particularly in the dark. (Like in humans, genetic differences can still cause poor vision in individuals.) They also have an excellent sense of smell. Their gills differ from those of moray eels and even other fish; they have 5 exposed gill slits that are superficially similar to those of sharks. They can survive indefinitely on land, indicating that they also possess lungs.

Diagram of pharyngeal jaw extension. Various muscles and connective tissue attach the jaw to the throat.

With a few exceptions, most eel monsters have large pointed teeth, with elongated canines or multiple rows of teeth found in some morphs. They have pharyngeal jaws analogous to those of moray eels, but they can extend a fairly large distance out of the mouth. The pharyngeal jaws appear to function independently.

Human form

In human form, eel monsters are mostly indistinguishable from H. sapiens individuals, but they retain their slit pupils, sharp teeth, and gills on their necks. Most choose to hide these features when interacting with humans. This behavior must be learned, and it requires effort to do so. There are also limitations: their irises remain the same color, and their canines remain abnormally sharp.


While destructive eel monsters make up the vast majority of sightings, eel monsters as a whole are not innately aggressive. The majority of the population live uneventful lives in human society or the ocean. Although most eel monsters typically stay in one form, it is not unheard of for some to permanently change forms. The transition is often more difficult for those that choose to leave the ocean for human society due to the complexities of human culture and economics.

Hunting behavior varies depending on habitat and availability of food species. Some eel monsters are ambush hunters, while others chase their prey. They are more agile than their size would suggest, especially in the water. On land, their speed suffers, but they have stamina that allows them to chase faster prey until it tires. They also use their pharyngeal jaws to trap prey and pull it into their mouth; this differs from moray eels, who restrain their prey with their primary jaws before pulling it into their throat with the pharyngeal jaws.

After an eel monster eats, it cannot shift into human form until digestion is complete; this is potentially problematic for those who live as humans.

The social behavior of eel monsters is almost completely unknown. Individuals who live predominantly human lives and shift into eel form can understand their language(s) and respond to them nonverbally. They also retain their ability to express emotion. It is unknown whether these things are innate or learned from humans. The family structure of eel monsters outside of human society is also unknown (e.g. whether they live individually or communally, if parents care for their young, if they can form bonds with others).


Eel monsters are mesocarnivores, preferring to consume meat and not being able to live without it, but still being able to digest non-animal food items. Furthermore, they can seemingly digest any material, organic or inorganic, without suffering the effects of any toxins or byproducts. Extremely little is known about the digestive system and what enables them to do this. The stomach is presumably extremely acidic, but it is unclear whether the body is extremely efficient at detoxification or if the toxins are simply destroyed before they can leave the stomach.

Eel monsters living in human society typically adopt human diets, though they must take care to monitor their meat consumption. People who live in coastal cities may choose to hunt in the ocean to ensure they eat sufficient amounts of meat, but the demands of modern life mean that most cannot afford the inconvenience of waiting for their food to digest in eel form. Many people also have a mental aversion to eating raw meat or live animals despite being capable of doing so.

One fact of note is that eel monsters are reportedly willing to hunt and eat humans, even when other food is available. Though there have been claims of this occurring, none of them have been verified.

Reproduction and life cycle

Life cycle

The early stages of the life cycle of an eel monster depends on the form it was born in. An individual born in eel form begins as a larva that resembles the leptocephalus of a moray eel. The leptocephalus will soon begin to grow legs, though it has no motor control over them until it metamorphoses into a juvenile. Conversely, an eel monster born in their human form will grow like a human child. Due to the fragility of the leptocephalus, eel monsters cannot change from the form they were born in until metamorphosis is (or would be) complete, which typically takes about 4 or 5 years.

The life expectancy of eel monsters is unknown. It is hypothesized that they live roughly as long as humans.


Eel monsters can reproduce in both their human and eel forms, though the mechanics of eel reproduction are unknown. The reproductive process in their human form is identical to that of humans, and they can reportedly reproduce with humans. (There are no verified instances of this happening, either.)


The phylogenetic relationship of eel monsters to the moray eel family Muraenidae is unknown. Their relation to humans is similarly indeterminate, despite them possibly being able to reproduce with humans. It is unknown if different morphs are reproductively isolated. It is also unknown whether any of the morphs warrant division into different species.