Why are there no really big bony fishes? A point-of-view on maximum body size in teleosts and elasmobranchs

Abstract

The most massive teleost, the ocean sunfish (Mola mola), is an order of magnitude smaller than the largest cartilaginous fish, the whale shark (Rhincodon typus), and is significantly smaller than several other extant elasmobranch species. Possible reasons for this discrepancy in maximum size include: anatomical, physiological, ecological, and life-history/ontogenetic constraints. We examined life-history traits and growth rates as the most likely constraints on maximum teleost size. For pelagic fishes there appear to be two life-history strategies: producing few, large, live young or many, tiny eggs. We propose that this dichotomy is an evolutionary vestige of the freshwater origins of teleosts, and is the basis of the limitation on maximal body size in teleosts.