222
4.3 Fish Scales, Scutes and Denticles:
Diversity and Structure
Fish scales are diverse according to shape and to content of main chemical components (see for review Williamson 1849 , 1851 ; Goodrich 1907 ; Kerr 1952 ; Sire 1990 ;
Sire et al. 2009 ). All of them are intriguing examples of naturally occurring calcium
mineral-containing biocomposites. The fi rst important studies which have been carried out on fi sh scale structure are those of Mandl ( 1839 ) and Agassiz ( 1833 –1844).
Mandl ( 1839 ) was the fi rst to demonstrate the heterogeneity of scale organization in
Teleosts (Fig. 4.3 ), against Agassiz’s opinion, and he described how their structure
is stratifi ed with layers of parallel fi bers whose directions shifted from one layer to
the other (Meunier 1984 ). Williamson ( 1851 ), Baudelot ( 1873 ) and Hofer ( 1889 ) all
confi rmed the fi brillary nature of the basal plate and the regular change of the fi bers’
orientations, without giving, however, a thorough analysis of these changing fi brillar orientations. Mandl ( 1839 ) misinterpreted “ corpuscles ” as meaning cells. Later
Williamson ( 1851 ) and especially Baudelot ( 1873 ) demonstrated, in their fi ne contributions, that those structures were mineralized concretions.
According to Sire and Akimenko ( 2004 ), in “fi sh literature, the term ‘scale’ is
often used as a generalised term for all the hard, generally fl attened, skeletal elements found in the skin of aquatic vertebrates. These include the scales of:
– chondrichthyans ( placoid scales ),
– the scales of basal actinopterygians ( ganoid scales ),
Fig. 4.3 Heterogenous character of Permian fossil Elonichthys punctatus fi sh scale. Arrow indicates the direction of scale growth. Abbreviations: o odontodes in a single layer, d dentine, en
enamel, i isopedine (Reprinted from Dias et al. ( 2010 ) with permission. © Copyright 2010 by
Unisinos)
4 Fish Scales as Mineral-Based Composites
4.3 Fish Scales, Scutes and Denticles:
Diversity and Structure
Fish scales are diverse according to shape and to content of main chemical components (see for review Williamson 1849 , 1851 ; Goodrich 1907 ; Kerr 1952 ; Sire 1990 ;
Sire et al. 2009 ). All of them are intriguing examples of naturally occurring calcium
mineral-containing biocomposites. The fi rst important studies which have been carried out on fi sh scale structure are those of Mandl ( 1839 ) and Agassiz ( 1833 –1844).
Mandl ( 1839 ) was the fi rst to demonstrate the heterogeneity of scale organization in
Teleosts (Fig. 4.3 ), against Agassiz’s opinion, and he described how their structure
is stratifi ed with layers of parallel fi bers whose directions shifted from one layer to
the other (Meunier 1984 ). Williamson ( 1851 ), Baudelot ( 1873 ) and Hofer ( 1889 ) all
confi rmed the fi brillary nature of the basal plate and the regular change of the fi bers’
orientations, without giving, however, a thorough analysis of these changing fi brillar orientations. Mandl ( 1839 ) misinterpreted “ corpuscles ” as meaning cells. Later
Williamson ( 1851 ) and especially Baudelot ( 1873 ) demonstrated, in their fi ne contributions, that those structures were mineralized concretions.
According to Sire and Akimenko ( 2004 ), in “fi sh literature, the term ‘scale’ is
often used as a generalised term for all the hard, generally fl attened, skeletal elements found in the skin of aquatic vertebrates. These include the scales of:
– chondrichthyans ( placoid scales ),
– the scales of basal actinopterygians ( ganoid scales ),
Fig. 4.3 Heterogenous character of Permian fossil Elonichthys punctatus fi sh scale. Arrow indicates the direction of scale growth. Abbreviations: o odontodes in a single layer, d dentine, en
enamel, i isopedine (Reprinted from Dias et al. ( 2010 ) with permission. © Copyright 2010 by
Unisinos)
4 Fish Scales as Mineral-Based Composites