Leviathans are closely related to hydrophis spiralis. Some characteristics of these leviathans include:

  • continuing to grow until they die and are able to grow almost as large as a blue whale
  • are warm blooded similar to mosasaurs, birds, and mammals (optional)
  • experience negligible senescence
  • scales are made of the same material as Limpets teeth
  • are carnivorous
  • rarely breed
  • give live birth similar to mosasaurs
  • can spit out a burning spray similar to a bombardier beetle

Given these characteristics, could such a creature realistically exist and what evolutionary pressures would lead to them?

NOTE: magic does not exist in my story

  • 3
    $\begingroup$ Yes, it could exist. $\endgroup$
    – user75689
    Commented May 30, 2020 at 20:30
  • 3
    $\begingroup$ warm blooded and negligible senescence are more or less mutually exclusive they represent two very different approaches to life, warm blooded creatures grow very quickly and are highly active, this however means your cells need to divide fast which causes problems unless you also have so solid controls against unlimited growth.. It is like saying you want a car that has very high acceleration AND very good mileage, you can't have both. $\endgroup$
    – John
    Commented May 30, 2020 at 20:58
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    $\begingroup$ @John Not really, bowhead whales are warm blooded and are thought to be able to live to be over 200 years old. What causes a body to break down are in-built senescence issues (i.e., limited telomeres) and tissues that cannot be easily repaired due to the way they grow (cartilage, teeth in mammals). Most of these are actually circumventable and have been by various species, it's unknown why evolution puts all these handicaps on the bodies of living organisms in the first place. $\endgroup$ Commented May 30, 2020 at 21:23
  • $\begingroup$ the reason limited telomere exist IS to prevent cancers and other such problem rapid cell divisions risk. long lived mammals and birds actually have more of these limiting factors in place. there are also selective pressures to worry about a species that reproduces quickly but also lives a long time starts negatively impacting its own offspring through competition. senescence and growth rate follow a very predictable pattern. we may not completely understand why it happens but we have not found a single animal that deviates from it. $\endgroup$
    – John
    Commented May 31, 2020 at 3:00
  • $\begingroup$ 200 years is not negligible senescence, bowhead whales still show strong senescence it just sets in later, not that surprising considering they have very slow metabolisms for a mammal. their growth also plateaus just like other mammals. A bowhead whale that makes it to 100 is not going to grow at all, even if it lives another hundred years. $\endgroup$
    – John
    Commented May 31, 2020 at 3:14

1 Answer 1


The pressures for such a creature wouldn't be that different from those of a blue whale, and most likely neither would its habits. However some things don't seem to add up, despite being observed in nature, especially the senescence part, which, while observed in nature, is more characteristic to cold blooded and smaller creatures, being turtles the only vertebrates with such a trait, with the only exception being the naked mole rat , which has its negligible senescence mostly attributed to it's lower metabolic rate and relatively ectothermic nature (they have trouble staying warm). However, for it to be giant, it'll need to be endotherm, as that's the case with most instances of such large marine creatures (true, colossal squids are an exception, but that's mostly due to deep-sea gigantism, and is more characteristic to invertebrates). So while large animals like whales do have less chances of developing cancer and can have long lifespans, this doesn't equate to a lack of aging altogether.

The second problem would be it's scales, or rather, it's molting. I don't think your creature would molt like snakes do, especially at such large sizes. Rather, I believe it'd be something more similar to a pangolin than a snake, with a body covered in scales that are naturally shed and replaced over time, because something like this giant snake would never be able to molt properly, and as a consequence would likely become mostly blind and die due to infections and other problems caused by said failed molting.

Lastly the bombardier beetle spray. I truly don't think that'd be an effective defense mechanism simple because:

1-it's underwater, meaning it'll spread and affect it as well 2- the sheer volume of chemicals needed for a creature that size doesn't seem worth it.

Other than that, nothing too otherworldly to exist, just don't make it a scaled up sea snake, understand that it will age and die and (preferably) look for alretnative defense mechanisms more in line with an aquatic environment (maybe something like the hagfish's slime).


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