Metamorphosis of Elopomorphs - Metamorphosis in Fish - page 103

new habitats. The metamorphosis of eels is apparently triggered by thyroid
hormone and similar hormonal regulation is probably present in other
elopomorphs. Although other teleosts demonstrate different types of
morphological changes during metamorphosis, thyroid hormone in teleosts
appears to have the common function to induce a larva-juvenile transition.
Although the elopomorphs are a taxonomically low group of teleosts, they
possess the pituitary-thyroid axis and its specifi c receptor system is also
present. Because the lamprey has a different mechanism of regulation of
metamorphosis, it would be of great interest to examine the emergence of
thyroidal function in this vertebrate lineage.
Acknowledgements
A part of my own research was supported by a grant, The production of eel
juvenles, from the Ministry of Agriculture, Forestry and Fisheries. I thank
Dr. Tanaka for providing photographs of eel leptocephali and Dr. Kurogi
for giving a specimen of wild eel leptocephali.
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