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About Fishes

Ganoid Scales

A Florida Gar from the collection. View larger image.

Ganoid scales of a Florida Gar Lepisosteus platyrhincus Dekay, 1842.

Scanning electron micrograph of a Florida Gar ganoid scale. Note peg at upper left which articulates with adjacent scale.

Ganoid scales are found in fishes such as the bichirs (Polypteridae), Bowfin (Amia calva), paddlefishes (Polyodontidae), gars (Lepisosteidae), and sturgeons (Acipenseridae). They also occur in some fossil paleoniscoid fishes. No fishes in these families occur in Australian waters.

Ganoid scales are usually rhomboid in shape and have articulating peg and socket joints between them. They are modified cosmoid scales which consist of a bony basal layer, a layer of dentine, and an outer layer of ganoine (an inorganic bone salt).

Further reading

1. Helfman, G.S., Collette, B.B. & D.E. Facey. 1997. The Diversity of Fishes. Blackwell Science. Pp. 528.