hippos can open there about 3 feet or more depending on the size
They open it very wide.
the hippo would win because it has a big mouth.
You can't. You can only open your mouth as wide as your jaw will let you.
The hippos mouth is 4 feet (1.2m) and its teeth are big too. See: Hippopotamus - The Hippo's Teeth And Its Diet for more information.
A grown hippo usually has a mouth about 4 feet tall.
Open the mouth wide.
A hippo has the bigger mouth. Tasmanian tigers were about dog-sized, while a hippo's mouth is about the length and width of a mid-sized suitcase.
Birds
A python can open its mouth very wide to swallow prey, stretching up to four times the diameter of its own body.
The very large mouth of the hippopotamus is used to scoop up large amounts of aquatic vegetation, that the hippopotamus eats.
A hippo's tooth is about 13 in. wide. :)
roughly 65 degrees