HAVE WHALES ALWAYS BEEN THAT BIG?

Hello readers! Today,  with the second article of my  series,  I want to answer to this question :

 Have whales always  been that big ?

The blue whale is the biggest animal on Earth , you can swim into their artery and they have such a big network of blood vessels that if you laid them out in a line you could stretch them from the Sun to Pluto and back for two and a half times ,but ... unlike you would think whales haven’t always been that big , if we rewind the clock around fifty million years you wouldn’t  find any whale , you have to go ashore to meet the very first whale: the pakicetus. It wasn’t taller  than a dog, had legs with hooves and a long and thick tail .

                                                                          

  We are practically  sure of the kinship between these two animals for many reasons :

1. -          they have to emerge to breathe
2. -          the bones of their pectoral fins are the same of the terrestrial mammals
3. -          the movements of their spine  are vertical ( such as a running  animal on the mainland ) and not horizontal as fishes
4. -          in the ending part of the spine there is a pair of small bones which is what remains of their ancestors ‘ legs

                                                                     

How did the transformation happen? 

Life on Earth spent millions of years to get out of the ocean but pakicetus took all that effort  and threw out of the window jumping into the water . The transformation wasn’t  gradual, in thirty-seven million years whales grew increasingly diverse but their size remained small : one of the first whales with baleen was only five meters long and it was an easy prey for giant sharks . Only three million years ago when temperatures and currents shifted there was the disappearance of big predators and the increase of the availability of plankton and krill . The bigger they became the farther  they could travel seeking for food to grow up more and more. For example Humpback whales make one of the longest migrations of any mammal on earth from South pole to Central America  ( five thousand miles ) skirting South America .

Conclusion

The blue whale is so big that scientists think it has reached  a physical limit since the bigger it is the more water it engulfs and the more it takes to close the mouth (10 seconds on average ) , if the time increased most of the prey would escape leaving the whale without  food . So it ‘s possible we are living amongst the largest animals  that would ever exist . Luckily for us, they mostly just eat krill .

Giordano C.