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Locomotory design of ‘cyclostome’ fishes: Spatial arrangement and architecture of myosepta and lamellae
Author(s) -
Vogel Felix,
Gemballa Sven
Publication year - 2000
Publication title -
acta zoologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.414
H-Index - 37
eISSN - 1463-6395
pISSN - 0001-7272
DOI - 10.1046/j.1463-6395.2000.00056.x
Subject(s) - biology , anatomy , conical surface , evolutionary biology , geometry , mathematics
Vogel, F. and Gemballa, S. 2000. Locomotory design of ‘cyclostome’ fishes: Spatial arrangement and architecture of myosepta and lamellae. — Acta Zoologica (Stockholm) 81 : 267–283 In recent years, it has been established that the main features of the locomotory apparatus of gnathostome fishes (myoseptal and muscular system) have remained relatively unchanged throughout evolution. The petromyzontiforms (lampreys) and myxiniforms (hagfishes) display a similar way of undulatory locomotion as gnathostomes. We investigated whether the anatomical features of the myoseptal system that facilitate undulatory locomotion in gnathostomes are also present in lampreys and hagfishes. We present a description of the myoseptal system, including for the first time the spatial arrangement and fibre architecture in ‘cyclostomes’, using a clearing technique, microdissections, polarized light microscopy, and SEM. We revealed that the myoseptal system of the Myxiniformes, Petromyzontiformes and Gnathostomata are each constructed in different ways. Petromyzontiform myosepta lack the conical structures but bear tendon‐like structures in the flanking parts. Their central parts lack tendon‐like structures but possess a system of crossing collagen fibres. Myxiniform myosepta bear comparable conical structures as gnathostomes but a highly asymmetric spatial arrangement. The fibre architecture of myosepta is not comparable to any of the two remaining taxa. The collagen fibre architectures of the multiple horizontal sheets of lamellae in ‘cyclostomes’ and the gnathostome horizontal septum are comparable. Our results 1) support the monophyly of Myopterygii (Petromyzontiformes + gnathostomes and a sistergroup relationshop of Myopterygii and Myxiniformes; 2) demonstrate that considerable changes must have taken place in the locomotory apparatus early in vertebrate evolution.