Evolution of polymorphism

Question

What are the cost and restrictions or benefits of a creature being able to slowly morph from an animal to another while retaining memories?

The creature morphs to giant eagle then morphs into fish and then back to its original shape. While transformed, the creature retains all its mental abilities and memories.

Changing from one species to another is more like learning how to use a bike, can be difficult at first but then it gets easier.

Such creatures can also selectively morph only specific parts of their body,for example growing tails and wings or changing limb shape.

Question inspired by the Heteromorphic characters of Overlord

In YGGDRASIL, there existed a multitude of different races. They were generally categorized into three main races; namely the "Human" race, "Demi-Human" race, and "Heteromorphic" race. The following context below is a list of current races that were introduced so far in the Overlord series.

The shapeshift won't be instantaneous like in Overlord but might take a few days for things like changing the shape of ears and eyes or months for turning into a different animal.

Answer 1

flying fish is a logical predecessor: imagine

(a) a fish thag flies, like flying fish

(b) a bird that dives, like penguins

now, take ether example, first having part of the fish/bird's appendages to possess a foldable, yet large extension, for example, outer fin, or primary flight feathers. a fish tail and a bird tail is really not very different.

for the flying configuration, your creature extends their aerodynamic appendages, taking the eagle/puffin configuration, possibly right after leaping out of water, flapping them to take flight.

for the aquatic configuration, the creature retracts it's wings and can now swim, taking fish configuration, possibly before diving into the water.

this creature would be a inhabitant of the high seas: fish groups in very distant groups, so anything that hunts fish have to be able to: either) migrate for long distances, following shoals of fish or) being able to dive for a largh depth, therefore hving access to the more dispersed fish inhabitating the ocean bottoms and deep seas. and) being able to reproduce without vicinitu of land, unless a) is satisfied, and it can breed on shores.

this would require the creature to be able to move very far very fast, yet limiting the creature's energy requirement for daily activities, therefore, it hunts as a fish/penguin and moves as a bird/flying fish, it does not take the eagle/bird like configuration unless the available food soursees are scarce. bonus if the creature spawns in the water, which it must have at least one swiming phase, even if it have to hunt while flying.

the fish origin would be the standard: the gills of a fish can work, if properly configured, in a continuous airflow just as if it was a continuous waterflow, using a layer of mucus as the exchange medium, running the fish's body like a turbofan/piston propeller engine whild a bird's lungs probably wouldn't be able to take oxygen from water. it may be diving periodically for a long time, and surfaces to breathe regularily, while swimming to hint, just like penguins or cetaceans.

Answer 2

This is a very expensive ability to have. You need the genetic plan for multiple different forms. You need to be able to transition between those forms while still having every form in between viable (or use a cocoon type system). How is a giant cat with half grown wings instead of its front legs going to run and hunt? It certainly can't fly yet.

And yet you're right, these changes can't happen fast. Even weeks or months is remarkably quick for those sorts of transformations. A good model might be the transition of a tadpole into a frog, which you will note is viable at every stage of the cycle.

As to how this would arise? There would need to be an extremely pressing urge so I suggest hugely variable planetary conditions. Either it orbits a variable star, or has an eccentric orbit, or similar.

This would cause it to have massively different seasons and life to develop multiple ways to cope. Some would hibernate, some would leave seeds and die, and some would adapt to the seasons.

The cat form might hunt and feed itself up, it then hibernates for a few weeks to transform into a flying form which allows it to fly to another part of the world and transition into another form to hunt again. When the 10 year winter approaches as the sun cools it would transform into an aquatic form and dive below the ice.

It's a little far fetched but that sort of highly dynamic environment is the only thing I can think of that might drive something as drastic as you describe to evolve.

Answer 3

For evolution, what you need to start with is the ability to change between two somewhat different forms.

Suppose a life form lives in a jungle where there is a wet season where everything is underwater, and a dry season where the water is concentrated in a few rivers. (Parts of the Amazon are somewhat like this.) It would be advantageous to be able to switch between a form adapted to the dry season and a form adapted to the wet season. Maybe it could start with something as simple as growing webs between their fingers and toes.

These forms wouldn't have to be that different at first. Evolution would make them diverge more. And then, after descendants of this life form move out of the jungle, evolution would retain this switching ability, but the descendants would switch between forms optimized for different purposes.

With respect to evolution, one of these polymorphic creatures is going to be outcompeted by a single-body-type animal unless it has some good reason for needing to change from one body type to another. So I would guess most creatures on the planet would be monomorphic.

Answer 4

You can't without magic.

You simply can't change shape that drastically that fast, your are talking about months of transition time, you can only restructure bones and tissue so quickly. Worse you have a large creature changing breathing mechanism, digestive system, and metabolism so months will kill your creature, it will starve. There is a reason there are no animals of significant size that undergo metamorphosis.

you are going to have to either handwave it or invoke magic.

Once you do that, then the reason is easy, adaptability, human are a perfect example the more adaptable an organisms is the wider it will spread. humans invented things like clothing an shelter so they could survive in environments they never could without them, your creature is just doing it to their body instead of with technology. Your earliest shapeshifters would only be able to alter small things and it would evolve gradually from there. You may also want to go the "thing" route and have it sample said creatures to copy them, that will make it slightly more believable otherwise they are going to need massive brains to work out each transformation through trial and error.