So in my world of Horizon, there is a sentient species known as the Jar'keth that lives in the inner ocean of Enceladus. They resemble a mix between eels and catfish, and are slightly smarter than humans.

Despite being smarter than humans, they live in a primitive state due to not having any hands, tentacles, or any other grabbing appendage. This is because they have stayed largely the same for the past 5 million years, because they simply did not have any reason to evolve. This is due in large part because Jar'keth are the apex predators of Enceladus.

Unlike on Earth, the food chain of the Inner Sea is chemosynthesis based, similar to the bottom of our oceans. Creatures resembling fully aquatic manatees graze on rocky fields of tubeworms. This is logically because there's no sunlight.

Most creatures there see through a mix of echolocation and heat vision similar to a snakes', but many also have bioluminescence, to help light their paths as well as lure in prey. The Jar'keth have only primitive eyes, but communicate through a language of bioluminescent flashes similar to morse code. They also use their flashes to lure in prey.

I want to know how plausible this is. While simple life could exist on Enceladus, I have no idea if complex life could

UPDATE: For those of you wondering, yes, the Jar'keth are social animals, something I've heard is a driving factor in intelligence. Similar to lions they hunt in groups.

  • $\begingroup$ I take it you mean Enceladus, the moon of Saturn? $\endgroup$
    – user
    Jun 7, 2017 at 19:48
  • 4
    $\begingroup$ We have absolutely no idea what conditions are like in Enceladus's ocean; there's no way to know at present what nutrients are available. You can make up literally anything you want. $\endgroup$
    – Werrf
    Jun 7, 2017 at 19:53
  • $\begingroup$ It's probably completely black down there, so how and why eyes and lighting would evolve is difficult to explain. Looking for something like this for my own worldbuilging :/ $\endgroup$
    – Innovine
    Aug 17, 2018 at 10:11
  • $\begingroup$ @Innovine Possibly to see the heat glow of other animals. But then, to see temperatures of 273 K with the same resolution as a human you would need a pupil at least 4.5 centimeters in diameter. $\endgroup$
    – Pyrania
    Sep 1, 2018 at 10:19

2 Answers 2


The biggest problem I can see is the question of why your species has intelligence.

As an apex predator without hands and a light lure rather than pack hunting, tool using and problem solving requirements, wasting energy on high intelligence seems redundant.

  • $\begingroup$ Please read the question thoroughly, it was stated that "For those of you wondering, yes, the Jar'keth are social animals, something I've heard is a driving factor in intelligence. Similar to lions they hunt in groups." Which contradicts your answer (although not entirely) $\endgroup$ Jun 8, 2017 at 4:59
  • $\begingroup$ @CameronLeary, timestamps would be your friend if they weren't so vague. $\endgroup$
    – Separatrix
    Jun 8, 2017 at 7:03
  • $\begingroup$ @CameronLeary I think his point is that it doesn't sound as though they are pack hunters. And even if they are, much like lions, it doesn't mean they will be capable of high intelligence. At best they sound like they would reach the level of cuttlefish. $\endgroup$
    – Firelight
    Jun 8, 2017 at 11:22

I don't think this is plausible. How did they become smarter than humans?

The most plausible route to Intelligence is that it evolves in an environment where it is useful, that is where it exists in all known intelligent species in real life. That pretty much excludes apex predators, they only need a limited amount of intelligence and rely primarily on brawn: Look at the Great White, look at the Lion. They don't rely on strategy, they rely on claws, teeth, speed and brute strength. None of which we humans are blessed with; we did not "grow up" as apex predators, we grew up as their prey; one can see that in the archaeological record. And, unarmed and naked on a field, the best of us have little chance against a young male tiger, even one our own weight.

What is the evolutionary pressure that caused these creatures to become increasingly intelligent over millions of years?

For the purpose of this discussion, consider "intelligent" as being better able to mentally model nature, prey and predators: Increasing intelligence is better models; along with the mental ability to use these models to simulate various outcomes: Letting them set traps for prey, or make themselves safe from predators by devising barricades they cannot figure out how to circumvent, to kill remotely (like we did with spears and slings), etc. In other words, these simulations allow imagination.

Eventually, in humans, we had runaway intelligence; one hypothesis is that at some point we were safe enough from nature that our biggest threats came from other humans, and that self-referential evolutionary pressure to outwit our own species became a maximizing feedback loop; meaning we became as smart as our biology could evolve to be, without further mutations killing us.

For your creatures, their biology could perhaps be pushed further, but you need an outside driver to push them to the tipping point, where they are their own biggest threat. An easy route toward that is basically the human route: we are one of the weakest and most pathetic animals on the planet! In terms of eyesight, hearing, olfactory sense, tasting sense. We have poor speed, poor strength (even compared to a chimp), poor reflexes, pathetic 'claws', poor canines, poor hide for any kind of protection. We are born defenseless and stay that way for years (compared to hours for other animals).

Apex predators don't have those problems, so their survival does not depend on their intelligence. Since brains are massive fuel hogs and evolution is ruthless in conserving energy to prolong survival, only animals whose very survival (at current levels) depends upon intelligence will continue to have it. It is always very easy to evolve toward less intelligence, and very hard to evolve toward more intelligence. Predators do need predictive models of their prey and their own capabilities, perhaps how to track and find them. That is more than their prey needs but not a particularly high level of intelligence.

With regard to biologically expensive intelligence, the path of least resistance for all animals is "just enough to survive and reproduce." The Jar'keth need a reason to be mortally terrified of something, so every little bit more intelligence (accuracy of prediction) they evolve means more of them avoid early death.

  • $\begingroup$ Pathetic: note that this can be an evolutionary consequence, not a cause of intelligence. Consider our strength difference with Neandertal as a middle ground: we traded strength for precision, as being able to throw accurately was an advantage. Once “tool usage” becomes the immediate environment that the animal operates in, further evolution will drive its utility as a tool user above all else. $\endgroup$
    – JDługosz
    Jun 8, 2017 at 10:18
  • $\begingroup$ @JDługosz It can be both, both a floor wax and a dessert topping! (HT to SNL). The ancestor of both Neandertals and Homo Sapiens was Heidelbergensis; more of a halfway point (in physicality) between the two, and we have artifacts and grave sites/goods suggesting HB was conscious, self-aware, perhaps even religious; probably so was Neandertal. Pathetic and Intelligent can create a feedback loop so each is the cause of the other: More intelligence reduces physicality needed, making intelligence a necessity and more intelligence more advantageous, reducing physicality requirements, ad infinitum. $\endgroup$
    – Amadeus
    Jun 8, 2017 at 11:27
  • $\begingroup$ Humans can actually throw things much faster than a chimp. $\endgroup$
    – Demi
    Jun 10, 2017 at 17:01
  • $\begingroup$ Humans actually aren't that pathetic or poor if you really compare them to ALL the animals on the planet. They look poor if they are compared to the best of the best of each category respectively. For example, our eyesight is actually quite good. Maybe not if you compare it to an eagle, but eagles therefor have other disadvantages. Not accounting for intelligence, Humans are are more or less jack of all trades, master of one (that being endurance). $\endgroup$ Nov 8, 2022 at 13:40
  • $\begingroup$ @EisGeflüster Humans are a top predator, shaped very much like a prey animal. Despite strength, Neandertals were strong, but were close up hunters and the typical Neandertal skeleton has numerous broken and healed bones. I compare humans and our immediate ancestors to other predators, not to the prey animals, even though modern humans are shaped very much like prey animals, with similar features, and virtually no biological defenses. Like I said five years ago, there can be a feedback loop; because of intelligence we have lost most of any biological ability we once had to defend ourselves. $\endgroup$
    – Amadeus
    Nov 8, 2022 at 14:53

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