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Which hormones control salamander metamorphosis?

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Study an amphibious tiger salamander of the mole salamander family Ambystomatidae in its natural habitat — Caudata Tiger salamanders (*Ambystoma tigrinum*) are widespread across much of the United States. Although they are generally black with yellow blotches, bars, spots, or even stripes, some are lighter in colour or have olive markings. Tiger salamanders belong to the mole salamander family, Ambystomatidae.

In amphibians, including those in the order Caudata, metamorphosis is controlled by hormones that regulate development and physiological change.12

The process is primarily driven by the hypothalamic-pituitary-thyroid axis. The hypophysis (pituitary gland) secretes thyrotropin, which stimulates the thyroid gland to produce and release thyroid hormones, most notably thyroxine. These hormones circulate through the blood to target tissues, where they initiate and coordinate the diverse morphological and biochemical changes required for the transition from a larval to an adult form.2345

While the structural modifications in salamanders are generally less dramatic than those observed in anurans (frogs and toads), the underlying hormonal mechanism remains consistent across amphibians. The specific effects of these hormones depend on the competence of the target tissues, which respond to the hormonal signals by undergoing processes such as tissue resorption or the development of adult structures.415