Explain how animals communicate in such a biologically dense ecosystem

There is no universal auditary language common to the different species of animals. Instead they rely on modes or methods of communication which we can categorize to communication by sound, by visual, by body language and by chemical means. Chemical means through pheromones they secrete in the atmosphere for some species, e.g. bees, wasps ants. etc.

British cologoinst admisitrion