In my last question, How large could my sea serpents be?, I asked what length would be a) possible and b) necessary for a whale-eating sea serpent. My sea serpent is a constricting predator* in a clade with Muraenidae.

The only answer I got there was nevertheless rewarding, and I recieved a great method of calculating the size of a constricting predator. So, here are the dimensions of the sea serpent:

  • 50 metres long
  • 1.25 metres wide
  • 65,000 kg in weight

As it stands, this is my very rough diagram of sea serpent internal anatomy:

enter image description here

Note: they have reproductive organs and esophagi, I just forgot to put this in the diagram

So, what changes, if any, do I need to make to this creature's anatomy to sustain a 65,000 kg moray eel?

I know of some features that help sustain large animals, like large hearts, pressurizing muscles in the jugular vein, and bundles of nerve ganglia to serve as "second brains". Do I need any of these, or others?

*Some people, in my last question, believed that constriction is not a good method of predation in the ocean. I disagree, but what ever you think, please don't bother to bring it up in the comments. The entire dimensions of this animal have been based on it being a constrictor, so there's no point in re-raising the same statement now.

  • $\begingroup$ I suggest some additional 'hearts' along the body length. $\endgroup$
    – Daron
    Jun 10, 2018 at 14:12
  • $\begingroup$ @Daron Would these be true hearts, and if not, what would I call them? $\endgroup$
    – SealBoi
    Jun 10, 2018 at 14:55
  • $\begingroup$ Probably just 'hearts' or 'secondary hearts'. $\endgroup$
    – Daron
    Jun 10, 2018 at 15:35
  • $\begingroup$ @Daron Okay, thanks. $\endgroup$
    – SealBoi
    Jun 10, 2018 at 15:46

2 Answers 2


Very long dinosaurs are theorised to have an extra brain somewhere near the pelvis. This brain is not used for thinking $-$ it's just a nerve cluster that gives signals from the head a signal boost. I believe the modern concensus is these theories are false. However one animal that does have extra nerve clusters is the octopus. There is one per tentacle but this is not due to size.

But it raises the issue that the tail being very far from the head might make circulation difficult. Not neural circulation but blood circulation. To fix this you need either a very large heart or, alternately, several smaller heart-like pumps along the length. Some animals have several hearts. For example octopus have three and cuttlefish have two.

What should we call these heart-like pumps? I see no reason that specialists (and everyone else) wouldn't just call them hearts. Or maybe secondary hearts to distinguish from the larger heart closer to the head. After all, the heart of a human is an entirely different machine to the heart of an octopus and we use the same term.

Specialists will have technical terms to refer to the various parts of the secondary hearts. How different they are from the terms for parts of the human heart will depend on the exact anatomy.

  • $\begingroup$ Should these secondary hearts, do you know, be located along the dorsal aorta or branch from it? $\endgroup$
    – SealBoi
    Jun 10, 2018 at 16:54
  • $\begingroup$ I imagine each should be at a major T-junction of the dorsal aorta that supplies that section of the body. $\endgroup$
    – Daron
    Jun 11, 2018 at 12:47

Moray style constriction, not anaconda style constriction.

  1. Constrictor snakes swallow prey whole. Constriction subdues the prey but big constrictor snakes need jaws that unhinge to accommodate large prey like pigs or people. Eels that swallow whole prey substantially larger than themselves need special jaws too. If you want that for your giant eel you could take a page from the [gulper eel] playbook.

http://www.factzoo.com/fish/gulper-eel-pelican-frightening-jaws-deep-sea.html gulper eels

  1. Even better, though is to stay true to the moray. You do not need to invent much. Moray eels do not swallow large prey whole - they bite off chunks like a crocodile. But morays do a trick similar to that of constrictors. They use their body for leverage against a large prey item.

Moray Eels Knot Themselves to Pry Prey

Another, a fimbriated moray, held the mesh bag with its mouth while its tail looped a loose overhand knot. The knot moved up its body, over its head, and pushed hard against the bag while it tugged with its mouth. Then the knot unravelled and the moray looped another knot. It repeated this over and over again for 90 seconds in its efforts to break the bait bag or squeeze the crushed fish bits through the mesh.

Moray type constriction holds live prey still so it can take bites. Killing the prey is a possibly unnecessary byproduct.

moray wrapped around fish http://www.divephotoguide.com/underwater-photography-special-features/article/behind-shot-eel-tang/

This application of constriction keeps your constrictor sea serpent, is more true to the moray and sidesteps shortsighted complaints about constriction being poorly suited for aquatic predators. It is more versatile as well - a truly large prey item (or a ship) too large to be wrapped around could be bitten, and then the knotted body of the eel pushed against the prey to break loose the bitten chunk.

Also it is more terrifying to be eaten while alive than it is to be suffocated by constriction. You might even have your wily serpent purposefully bite off pieces that will not immediately kill the prey. Killing an animal too big for the eel to eat at once just subsidizes its competitors like sharks. Crippled prey that swims away can be fed upon another day.


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