Vol. 64, 2025
Evolutionary Insights into
Muscle Fiber Distribution in the Twin Tails of Ornamental Goldfish
Kinya
G. Ota1,* , Gembu Abe2 , Chen-Yi Wang1 , Ing-Jia Li1 , Paul Gerald Layague Sanchez1 , and Tzu-Chin Chi1,3
doi:-
1Laboratory
of Aquatic Zoology, Marine Research Station, Institute of Cellular and
Organismic Biology, Academia Sinica, Yilan 26242, Taiwan.
*Correspondence: E-mail: otakinya@gate.sinica.edu.tw (Ota)
E-mail: likeguepardo@gmail.com (Wang); leinja0@gmail.com (Li);
sanchezpgl@gate.sinica.edu.tw (Sanchez); chitzuchin@gmail.com (Chi)
2Division of Developmental Biology, Department of
Functional Morphology, School of Life Science, Faculty of Medicine,
Tottori University, Nishi-cho 86, Yonago 683-8503, Japan. E-mail:
gembu.catfever@gmail.com (Abe)
3Collection Management Department, National Taiwan
Museum, Taipei, 100007, Taiwan
(Received 4 October 2024 /
Accepted 12 January 2025 / Published -- 2025)
Communicated by Yi-Jyun Luo
Twin-tail ornamental goldfish have
a bifurcated caudal fin with a morphology that is extremely divergent
from the conventional body plan of the vertebrates. Here, we
investigate the musculoskeletal histology of this bifurcated caudal
fin. From some of the investigated twin-tail goldfish, we found a
twin-tail goldfish specific muscle (hereafter referred to as the
“medial caudal muscle”) between left and right bifurcated caudal fin
skeletons. Our immunohistochemical analyses revealed that the medial
caudal muscle showed laterally biased distribution patterns of the slow
and fast muscle fibers. Similar distribution patterns were also
commonly observed in several deep muscles of wild-type goldfish as well
as zebrafish, suggesting that these muscle fiber distribution patterns
are formed by the same molecular developmental mechanisms even though
their morphologies are highly diverged. These findings provide
empirical evidence to consider how the histological features of a newly
emerged morphology are influenced by selective pressures and
pre-existing developmental mechanisms.
Key words: Slow muscle, Fast muscle, Carassius
auratus, Somite derivatives, Axial skeleton
Citation: Ota KG, Abe G, Wang CY, Li IJ,
Sanchez PGL, Chi TC. 2025. Evolutionary Insights into Muscle Fiber
Distribution in the Twin Tails of Ornamental Goldfish. Zool Stud 64:04.

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