[Lee Stewart]

It's a myth that all sharks have to swim all the time or else they drown. This comes from the fact that sharks don't have a swim bladder which means if they stop swimming they will sink. Shown are a group of nurse sharks resting on the bottom of a shallow coral reef. They can stay there for hours at a time.The ocean current is enough to force water into their gills.

For deep water sharks it's different. They do have to swim all the time, even when sleeping to avoid sinking.