Question on Nurse sharks and sinking.?

Question

Nurse sharks spend most of their time lying on the bottom of the ocean. Given what you know about cartilaginous fishes like sharks, which of the following methods do you think nurse sharks use to sink to the bottom?
Do they ajust the amount of gas in their swim bladders
Do they adjust the amount of air sacs.
They stop swimming and sink.
Or do they kick their webbed feet?

Please no rude comments.

Answer 1

Sharks have no swim bladder, air sacs, or webbed feet. The answer is that they stop swimming.

http://www.amonline.net.au/fishes/students/dissect/swimbladder.htm