A predatory fish evolves adaptations that make it more adept at catching smaller fish. In turn, the smaller fish evolve means to be evasive, leading to more selection on the predators to be still better able to catch their prey. The interaction between the two species is an example of a(n)

an evolutionary race (i.e., coevolution)

Explanation:

Coevolution is a phenomenon where two or more species affect each other's evolution through the mechanism of natural selection. During coevolution, species start an evolutionary race, where one species adapt and change (i.e., evolve) in response to another species, thereby countering the adaptive effects of the first one. An example of coevolution is the evolutionary race between predators and preys, like the example above.

the reason the two sea urchins don't compete with each other for food, resources, etc. is because the urchins have adapted to the environment but they have also adapted to each other. this is most likely because the genes of the sea urchins.