In my world, one of my creatures is a 100kg, 2 meters long flying alien. It has a durable yet relatively light endoskeleton which allows it to have proper anchoring for its flight muscles and its overall appearance seems something between a bat and an azhdarchid pterosaur. However, I'd like it to have a "backup plan", in which, should it undergo wounds that hindered it's mobility to the point it could no longer hunt, it'd undergo a "salvation process", essentially eating itself, following by a "second" creature bursting from its insides.

The "second" creature, very reminiscent in overall shape and abilities to an octopus, is in fact a survival strategy. These creatures begin their lives by leaving their chicken-sized eggs as Cephalod-like creatures, which then begin their efforts for survival. After reaching maturity and accumulating enough biomass (resulting in them becoming slightly larger than a giant pacific octopus) , these creatures will essentially enter a "pupa" stage, in a process which will result into the body "shrinking" to a smaller size and creating a capsule around it, with this emergency body housing most vital organs and structures, such as the brain, lungs and digestive track. The "emergency body will have its excretion openings linked to the main body formed around it, as well as having linked blood vessels and nervous system (at this stage, the emergency body essentially acts as a second layer of protection to the main organs and lies in a dormant stage, with the main body truly housing only this emergency body, the necessary musculature, the skeleton and the reproductive structures, all naturally covered by a second layer of skin). Upon major damage to the main body, the "emergency body" will salvage as many nutrients as possible from the main body, sever these connections and burst out of it, starting over its cycle of growth and metamorphosis into its "adult" form. As an adult, the emergency body occupies most of the abdomen, where on earth would be the organs, and part of the skull. What I'm willing to achieve partially reminds me of of the Krang, a fictional species of soft aliens which build themselves robotic bodies for protection and were a good example of what I'd like my creature to be.

Summing up, could a creature with such a life cycle and defense mechanism involving housing a body inside another possibly exist in any way?


2 Answers 2



So... Organic Daleks? I'd one-up this idea and say they are symbiotically living with a different species that's closely evolved with them, and that is relatively unintelligent but very responsive to influence. The 'pilot' organism is smart, and guides the breeding of the 'mecha' organism, or even several varieties, depending on the needs.

Your pilot species is developing mecha more than technology, it wouldn't even need to be a fully sentient species if you didn't want it to be (although it would be a good one). Losing a mecha would be like losing an old dog - traumatic, but survivable. And your pilot species could breed new mecha for each environment it encountered. Desert mecha, flying mecha, sea mecha, etc. The possibilities are endless and all biological.

If you want your species to become technological, genetics might come before metallurgy. You could justify cyber-mecha easily, and eventually even vacuum-resistant mecha suits with chemical oxygen reserves for travel in space. Your pilot species doesn't need to evolve to adapt to new environments, just make better mechas.

  • $\begingroup$ I would have used the parelel to the independence day aliens $\endgroup$
    – Demigan
    Aug 21, 2021 at 13:21
  • $\begingroup$ @Demigan Their tech seemed more disposable, whereas a symbiotic relationship is a bit more life-long. But I get your point. $\endgroup$
    – DWKraus
    Aug 21, 2021 at 13:24

Lizard tails

Whether your idea is completely realistic I don't know, but I taste a fantastical element in there anyway. I would say it's possible, possibly with some evolutionary help to make it more plausible.

Lizards are already creatures leaving part of their tail behind if that tail is in danger. I'm assuming they instantly cut off all blood vessels and just scurry away.

For your creatures it would become much, much more complex. The problem is breathing and processing food. You have 2 choices. Separated indigestion and breathing is the first thing on my mind. During development, the octopus part will grow the outer parts, until the 'external' lungs and digestion have been properly grown to take over breathing for the whole body. Possibly small versions of breathing and digestion will grow first, then growing in size to support the whole structure. The octopus will rely fully on the secondary system, storing enough air in the lungs and food in the liver/fat for the emergency cut and escape. Conjoined indigestion and breathing might seem simple, as you might say it just grows from the original. Unfortunately it has some difficulties. The mouth and the breathing hole(s) grow to a certain size to accomodate for the right lungs and intestines. The creature might need to eat continuously small bites due to a small mouth, or have a too big mouth for it's size, making it a detriment. Same for breathing. And when you want to cut away, how do you separate the lungs and intestines? How will you close the wound you're making correctly?

Possibly you can start with conjoined intestines, growing larger for the full creature. When the body is large enough, you can seperate the parts, making the octopus again only connected with blood vessels, storing enough oxigen and such for the escape.

Conclusion I would say it's unreasonable. The complexity is too high. There are creatures able to seperate body parts or go back to earlier phases (might add a link to it later), but this complexity might be a step too far without bioengineering. So unreasonable, but not unthinkable.


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