About Fishes
Cosmoid Scales
Photo: C. Bento © Australian Museum.
Photo: C. Bento © Australian Museum.
Photo: C. Bento © Australian Museum.
Cosmoid scales are found in the Lungfishes (family Ceratodidae) and some fossil fishes. The top image shows the cosmoid scales of a Queensland Lungfish, Neoceratodus forsteri (Krefft, 1870). The middle image shows a whole Queensland Lungfish scale.
Cosmoid scales are similar to placoid scales and probably evolved from the fusion of placoid scales. They consist of two basal layers of bone, a layer of dentine-like cosmine, and an outer layer of vitrodentine.
As the fish grows each scale becomes larger as new bone is added to the basal layers.
The bottom image shows a Queensland Lungfish from the Australian Museum fish collection.
Related links
- Ganoid scales page
- Placoid scales page
- Cycloid and ctenoid scales page
- Fish Scales home page
Further reading
- Helfman, G.S., Collette, B.B. & D.E. Facey. 1997. The Diversity of Fishes. Blackwell Science. Pp. 528.
