Wiretwister:
They are tough ones Pat.
A hawk of one kind. Land animal is a Cheetah, marine I think is a barracuda but the hawk can travel at over 100 MPH in a dive.
While walking makes it a land animal, though maybe not exclusively. I will guess a croc or alligator when underwater.
To heavy and wing shape requiring a critical speed to be reached to get sufficient lift.
Thats the Viper or more commonly known as Adder. Diamond pattern on the back.
Biggest fish? Game fish of one kind a Marlin or maybe a Great White Shark. Definately not the Blue Whale because that is a mammal.
How did I do?
Well ! You got 3 & 4 right. Jammymut is right with ‘Horse’