Here’s my attempt at a great white shark. I can’t figure out how to model the gills, so I will just use mapping.
Great shape! looks like you even got the jaw muscles in the right spots
I never get decent shapes when I try modeling sharks.
for the gills I would just select a few edges and do a V to rip. then I would seperate the slit, and then select the edges of the slit again, and press F to have blender mend the hole with faces. (edge loop faces I think it is called)
We also have multires which would allow you to sculpt more details pretty easy.