05/25/2026
Metamorphosis in axolotls!
While we've seen the myth 'axolotls will morph when put through highly stressful and poor conditions' often enough, we hadn't seen the opposite claim 'axolotls will not morph if kept in optimal conditions' until recently. Needless to say, this is not true!
When metamorphosis occurs around 6-8 months of age and affects several siblings from a single clutch, we refer to it as 'genetic metamorphosis'. Cases such as these are thought to occur due to a genetic predisposition which results in metamorphosis when axolotls are exposed to environmental triggers. As for what those triggers may be, or which biological mechanisms are at play... The simple answer is, we don't know! Research on natural metamorphosis (not triggered by thyroxine injections) in captive axolotls in a laboratory setting hasn't yet been performed.
***EDIT***
Since so many commenters seem to be under the impression that the first myth (axolotls will morph when put through highly stressful and poor/unsuitable conditions) is true, here's a link to an examination of the existing research on metamorphosis in Ambystoma mexicanum from Lake Xochimilco. Both paedomorphic and metamorphic sibling offspring were produced in early captive pairings.
https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2019.00237/full
