Why Don't Whales Sink?

This week, Mr Dobson posed the question "Why don't Whales sink?". He thought they should. After all, many whale species are HUGE and HEAVY! He thought they should all sink to the bottom of the ocean.


We had much discussion about this. Some of the ideas and reason that Room 7 came up with were

• Blubber. The blubber around a whales body helps it to float
• Air. Whales are air breathers and each time they take a breath, it helps them to float.
• Flippers and Flukes. The whale has evolved strong flippers, and a whale's fluke (tail) helps it to push upwards in the water.

Mr Dobson then proposed that it may also have something to do with sea water. Ever heard of the Dead Sea? The 'Dead Sea' is a lake where people float on the surface of the water, and can't sink. 
This is because the water in the Dead Sea is dense with salty minerals, a lot like sea water. The water out of a tap (fresh water) is less dense than salty water. 

Maybe heavier objects float better in salty water?

To test this out we We tried floating  raw eggs (whales ) in both tap water and salt water to see if there was any difference.

  

We put the eggs in cups with tap water and salty water .

In tap water the egg sank and in salty water the egg floated.

This seemed to prove that object (like whales) float better in denser water (like the ocean) than in fresh water.