Many species of amphibians, fish, arthropods and even certain reptiles go through metamorphosis. But, to my knowledge, there are no mammals that go through metamorphosis.

Let's say I want there to be a mammal species that goes through a metamorphosis. During this metamorphosis they would start and finish puberty, hit their major growth spurt and grow 1.5-2.5 times their size.

What I'm asking is: could a metamorphosis of this scale work? If it couldn't, why not and how could I make it work?

  • $\begingroup$ mammals simply grows bigger, all metamorphosis takes place inside wombs or eggs(platypus & porcupine) I'm not saying its impossible it just need drives(lab science) $\endgroup$ – user6760 Aug 25 '15 at 1:14
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    $\begingroup$ I don't know about mammal metamorphosis, but this speculative evolution project provides a fantastic example of metamorphosis develops in birds, detailing how exactly this kind of detail can occur sites.google.com/site/worldofserina/the-thermocene-75/… $\endgroup$ – N Francis Sep 29 '18 at 22:37

Sure, it can work.

You're creating a new type of creature. As you say, they "are a mix of mammals and arthropods with some features of birds". Metamorphosis is low on the list of things I'd have a hard time believing after encountering such a creature.

There are several mechanisms you can use to get there, for a large creature it seems the most likely they would undergo incomplete metamorphosis triggered with hormonal control. This allows them to become several times larger without needing to build and enter any kind of chrysalis.

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    $\begingroup$ +1. You also might call puberty a sort of metamorphosis, though not exactly on the scale the OP is asking for. The biggest reason I see for mammals to not undergo metamorphosis is simply that they are usually adaptable enough to the environment that they don't need it... but there's no reason you couldn't create a world with that need. $\endgroup$ – Cort Ammon Aug 25 '15 at 1:03
  • $\begingroup$ @CortAmmon That last is the key, if the OP wants this to be "scientifically believable". Create a need and one can make the argument that life will find a way (this was established even in Jurassic Park: "life finds a way"). Some gradual development history could help, too. Absent the need, something like what the OP describes is highly unlikely to occur spontaneously, let alone be passed on to future generations. $\endgroup$ – a CVn Aug 25 '15 at 12:22

The changes humans go through in puberty, from a more or less uniform body plan for both sexes to a differentiation in body size, strength, hair growth and behavior is not as extreme as caterpillar to butterfly, but is quite a change. You could take that as a model to build a more elaborate change in body plan for your mammal.


I had a similar post, Metamorphosis Lycanthropy. All rapid development changes are technically a metamorphosis. But if you want a caterpillar-like metamorphosis for a mammal, I would have the mammal create a large shell or protective barrier, eat a lot for the calories/fat then go inside and morph however it does. The food is for energy/fat. Caterpillars will keep gorging in till it is time to go into the cocoon.

If you don't want a chrysalis, they could just grow a lot in a short amount of time and have lots of physical/mental changes to them. It's really up to you.

For info on catapillar metamorphosis you can see: https://www.scientificamerican.com/article/caterpillar-butterfly-metamorphosis-explainer/.

  • $\begingroup$ This response is rather short; really a one-liner. Can you please edit it? Not only to break up the run-on sentence, but also to build on your theme. How will going into a shell help with such a transformation? How will eating a lot help? A response like this does risk being flagged for deletion. $\endgroup$ – elemtilas Sep 29 '18 at 22:20
  • $\begingroup$ Is this good? I don't always explain my thoughts well. $\endgroup$ – user55812 Sep 29 '18 at 23:06
  • $\begingroup$ An improvement! Basically, the point of offering a response on SE is to both answer the OP's question and explain & illustrate your answer so that it will be helpful not only to the OP but also to other people who may wander this way in years to come. That's why we like people to their best effort into every query and answer they write! If you're having difficulties explaining your thoughts, and also because you're pretty new to SE, I would suggest you review the help center and take the tour. You can learn a lot about how the SE model works. $\endgroup$ – elemtilas Sep 30 '18 at 2:10
  • $\begingroup$ what does OP and SE mean, elemtilas? $\endgroup$ – user55812 Oct 1 '18 at 23:01
  • $\begingroup$ "Original Poster"; "Stack Exchange". $\endgroup$ – elemtilas Oct 2 '18 at 0:38

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