They depend on each other for food and shelter for survival as they go through different processes. Organisms depend on the other organisms for survival in different ways like parasitism and symbiosis. Symbiotic organisms depend on each other as well as parasitism as they feed on each other. The organism also depends on the environment for food in terms of decomposing and recycling.
Flowers depend on bees and other insects to feed on their pollen and travel to other plants to pollinate them. Bees are declining in number and this could be a real problem for our food supplies one day.