how do octopus’ fit into really small things? and how do under water creatures sleep?

Question: how do octopus' fit into really small things? and how do under water creatures sleep?
- Keywords:
  octopus,
  sealife,
  sleep
Asked by vickymufc to Charlotte, Jo, Kevin, Louise, Valeria on 15 Jun 2012.
- Kevin Mahon answered on 15 Jun 2012:
  
  Octopuses don’t have bones or any sort of shell or exoskeleton so their body is very squishy and easy to fit into small places!
  
  You’ll have to be more specific about underwater creatures before I can answer that! Do you mean fish? Or whales/dolphins?
- Joanna Cruden answered on 17 Jun 2012:
  
  I have had a look and sea animals like whales and dolphins rest half of their brain at a time so one half sleeps and the other half is awake to make sure the animal breaths.
  
  Some fish sleep with one eye open and some animals don’t sleep in the same way we do but have an energy saving rest period, all animals need sleep in one form or another.

Question: how do octopus' fit into really small things? and how do under water creatures sleep?