Sharks have to keep water moving over their gills in order to breathe, otherwise they will die. However, the creatures of the deep donÂ’t have to remain completely in motion to accomplish this.

They can lie on the seabed and effectively fan themselves by moving their gills to create a pump-like motion. However, not all species of sharks possess these muscles. The great white, for instance, does have to keep physically moving in order to survive.