ABSTRACT
The Ostariophysi, marine and freshwater worldwide, with nearly 8,000 species, contain 68 families of which the largest are the Cyprinidae, Characidae, Loricariidae and Balitoidae (Nelson 2006). They contain nearly three quarters of the freshwater fishes of the world, from carps (Cypriniformes) and the Neotropical tetras (Characiformes) to freshwater catfishes (Siluriformes) and the weakly electric gymnotids (Gymnotiformes). A small proportion, about 123 species, including the chanids and gonorynchids, are marine (Lauder and Liem 1983; Fuiman 1984; Nelson 2006). The Ostariophysi appears to be monophyletic on the basis of at least seven synapomorphies of which one is the presence in the epidermis of cells which exude an alarm substance when wounded; this causes a fright reaction which is evoked even in non-ostariophysans (references in Lauder and Liem 1983; Stacey, Volume 8B, Chapter 3). Monophyly of Ostariophysi has been endorsed by mitogenomic analysis (Lavoue et al. 2005) and by analysis of 8 nuclear genes, including 11,766 base pairs (see Orti and Li, Chapter 1, Fig. 1.4, and Fig. 11.1 below).
