Why are there no really, really big bony fishes?
The largest teleost (bony fish) that is ever known to have existed is the ocean sunfish (Mola mola) reaches is up to 1 500 kg in mass. The largest extant elasmobranch (cartilaginous fish) is the whale shark, Rhincodon typus, which can reach 15 000 kg, and several other sharks also grow larger than Mola mola. This ten-fold difference (one order of magnitude) is very biologically significant. Some extinct sharks and marine reptiles, as well as living whales also grow much larger than this. Since there are certain advantages to large size, it seems probable that some teleost would have grown to larger size, if it were able. It therefore seems likely that there is some constraint preventing teleosts from growing to such size. I investigated possible reasons for this large size discrepancy were investigated in this literature-review based study. These hypotheses included: anatomical constraints: bone versus cartilage, gill size, gas bladder, and fins • physiological constraints: metabolic r
