Large sharks are described as quite large-brained and intelligent in relation to most fishes. How large is their brain in proportion to their body in relation to other fishes, and what is their encephalization quotient, if such has been calculated for them? Is it near a modern reptile or small mammal, or less?

This is not a topic I know much about but it is an interesting question. I think it could be quite difficult to obtain samples at the same stage of development, or without plasticity changes due to environmental/social factors, and the brain structure of fish varies quite considerably across species. I also would imagine that there is considerable debate as to how encephalization and ‘intelligence’ might be related! I guess the EQ at least takes into account divergent body sizes across different types of fish. Rays are said to have the highest EQ amongst fish but sharks also rate highly, at least compared to tuna! see - … -animals/; … brain.htm. If the EQs ranges quoted in these articles are correct (0.25 to 2.77) that would place some sharks at the higher end above many modern reptiles and small mammals.

FYI, here is a link about the sizes of shark brains - … brain.htm, and a paper on fish brain size evolution - … 2212013863

Last edited by Steve Lolait (4th Mar 2015 11:18:38)