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Comparative development of scales and surfaces of fishes
Uherková, Michaela ; Černý, Robert (advisor) ; Vaškaninová, Valéria (referee)
1 Abstract The body surfaces of cartilaginous fishes (Chondrichthyes) and bony fishes (Osteichthyes) are composed of scales, with individual scale types differing in their morphological description, stratification, morphogenetic development and representation in each group. In fossil species, we encounter hard bony shells or plates, which gradually change during evolution to flexible scales of the elasmoid type, these are found in contemporaneous representatives of the bony fish group (Teleostei). Recent scale types found on the surface of present-day fish-like vertebrates include modified cosmoid scales, ganoid scales, placoid scales and elasmoid scales. Odontodes, which include placoid scales, ganoid scales, vertebrate oral teeth and pharyngeal teeth, are a key component in the evolutionary development of all these body surfaces. Odontodes form the basic structural unit of all dermo-skeletal structures and, from an evolutionary point of view, have evolved into the scales and oral teeth of vertebrates. Because of the interesting correlation between teeth and scales, a separate chapter of the literature review will be devoted to theories of the origin of oral teeth. The present bachelor's thesis discusses the evolutionary development of scales of cartilaginous fishes and bony fishes with respect to the...
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