[jarin]

Different species of bacteria have been shown to "communicate" via chemical signals, too. It's obviously not cognitive communication, but mating/threat displays between lower order animals can be considered to be just responses to stimuli as well.

Communication between plants may not be cognitive, but it's still the transfer of information.

[jdimov]

What's obvious about it? And what exactly do you mean by "cognitive communication"?

[jarin]

I mean communication between two organisms capable of cognition, i.e. language, mating displays, or other forms of communication that require a brain capable of interpretation.