Organisms living in open sea are called

Choose correct answer.

$(1)$ Zooplanktons are primary producers in an aquatic ecosystem.

$(2)$ Decomposition is largely an oxygen requiring process.

$(3)$ In a natural ecosystem, fishes, wolf, etc. are carnivore.

$(4)$ The amount of energy decreases in each successive trophic level.

In the following, there is no difference.

During food chain the maximum energy is stored in

The organisms, which attack dead animals are