Every deep dive is followed by three or four shallow dives. The elaborate dive patterns are assumed to be necessary to control the diffusion of gases in the bloodstream. No data show a beaked whale making an uncontrolled ascent, or failing to do successive shallow dives.[citation needed] This behavior suggests that the Cuvier's are in a vulnerable state after a deep dive – presumably on the verge of decompression sickness – and require time and perhaps the shallower dives to recover.