Peculiar Pirate Pet Puzzle - helpful hint one!

How are you getting on with the puzzle, shipmates?

Here's some help if you're stuck. 

Blackbeard’s pet cannot be the largest pet - a blue whale - because Blackbeard’s pet smaller than Jack’s. It can’t be the second biggest either - shark - because Mary’s pet is also bigger. So there are at least two pets bigger than Blackbeard’s. If you’re using the grid you can put two crosses in. 

Hint two coming up soon!