Question

How does the oil from the liver provide limited buoyancy in the absence of a swim bladder

Answer 1

Unlike fish, which have a gas-filled swim bladder that keeps them afloat in the water, sharks rely upon a huge, oily liver to provide some buoyancy. The oil in the liver is lighter than water and gives the shark some buoyancy, but it is still heavier than water and will sink if it dos not actively swim.