Why does an octopus have three hearts and not an whale? surely whales are bigger so they should have more? #FindingDory

Question: Why does an octopus have three hearts and not an whale? surely whales are bigger so they should have more? #FindingDory
- Keywords:
  heart,
  octopus,
  whale
Asked by Aleeeshyyy to Reka on 21 Nov 2016.
- Reka Nagy answered on 21 Nov 2016:
  
  That’s because they breathe through different means – octopuses have gills, so two of their hearts pump blood to the gills where the blood becomes rich in oxygen, while the third heart pumps the blood through their bodies.
  
  Whales, on the other hand, have lungs instead of gills (just like us), so they need to come to the surface to breathe – so they only need one heart to pump blood through their bodies, just like we do.

Question: Why does an octopus have three hearts and not an whale? surely whales are bigger so they should have more? #FindingDory