Answer:
Why are there no living cats on Mars?
I suck.
Good memory, skin like the sea. A great beast I am, yet vermin frightens me. What am I?
In wealth I abound; in water I stand; as a fencer I'm valued all over the land; at Venice I'm famous; by farmers I'm prized; respected by law yet huntsmen despised; consternation and ruin ensue when I break; And the beasts of the forest advantage won't take.
I am the kind of fish that chases a mouse.
I'm a god. I'm a planet. I measure heat.