Because during digestion, blood is needed to execute the process.
Swimming also requires blood so it takes the blood that was initially being used for digestion away.
Hope it helped!
Gaseous atoms and plasmic ions expand in all directions.
Go through this link it is has all your answers. What it is and examples. Hope this helps! (: http://study.com/academy/lesson/elastic-potential-energy-definition-formula-examples.html