Is it true that sharks die if they stop swimming?

Question: Is it true that sharks die if they stop swimming?
- Keywords:
  death,
  fact or fiction,
  lung,
  shark,
  swim
Asked by caitlynfarrar to Valeria, Charlotte, Jo, Kevin, Louise on 17 Jun 2012. This question was also asked by ludev13.
- Joanna Cruden answered on 17 Jun 2012:
  
  yes they will die if they stop moving in water
- Valeria Senigaglia answered on 18 Jun 2012:
  
  Some of them need to swim constantly because they are not able to “suck” water and they need water passing through their gills to exchange gas and obtain the oxygen they need.
  
  Other sharks however are able to actively suck the water and then push it outside through the gills. There are some sharks who live on the bottom of the sea and doesn’t move for very long period of time. In fact they hide in the sand waiting for their prey to get nearer and then they attack it.

Question: Is it true that sharks die if they stop swimming?