Answer:
Round like a dishpan and smaller than a bathtub. But the ocean can't fill it. What is it?
My first is a creature whose breeding is unclear. My second, a price you must pay. My whole can be found in the river of Time and refers to events of today.
I follow the orders of only two. I respect the work of only two. I am in constant battles with many, Though one surpassed them all. With forces joined, We created hell, Until our mutual enemy fell. Who am I?
Only two backbones and thousands of ribs.
It is the great nemesis of the lactose intolerant.
Pirates put their booty in it.