[Quantitative analysis of the teleost brain: evolutionary and adaptive features of encephalization. II. Primary brain...

1. Frequently there is an opposition between olfactory and visual senses. Fresh water fishes are generally macrosomatic and microptic, marine fishes (especially coral reef fishes) are microsmatic and macroptic while piscivorous pelagic fishes are macrosmatic and macroptic. 2. The importance of the cerebellum is a function of both the fish's activity level and its body size. 3. There is a marked opposition between the diencephalon and the medulla oblongata and a greater one between the non-olfactory-telencephalon (NOT) and the medulla oblongata (MA). Although it is not possible to give an accurate evolutionary significance, the ratio of NOT/MA is low in primitive teleostean fishes and high in more derived species (Acanthuridae and Tetraodontiformes).