A correlate to body curvature during swimming is the number of body segments. Although vertebrae number is certainly related to a fish’s phylogenetic position, fish that display different swimming modes commonly have different numbers of vertebrae. Anguilliform swimmers tend to have high numbers of vertebrae. For instance, the American eel
(Anguilla rostrata, Anguillidae) has103-111 vertebrae (Boetius 1980). Alternatively, the subcarangiform swimming rainbow trout (Oncorhynchus mykiss, Salmonidae) has 61-65 (Behnke1992); and the thunniformswimming skipjack tuna (Katsuwonus pelamis, Scombridae) has 40-41 (Hart1988).