They have radios stationed in all boats.
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Well, there are radios in MOST ships, and many boats. Besides radio, ships communicate with each other by horn signals. There is a standard set of signals that indicate actions that a ship is about to take.
Boats (people) can communicate silently with flags or light signals.
Plants cannot communicate with one another.
Cells in the body communicate with one another via signal transduction pathways. A cell needs to communicate with other cells to survive.
Electronically.
They communicate with each other by touching their antennae with one another. If red ants come upon another ant they do so to tell if they are from the same nest.
We communicate using sound waves by talking and listening to one another!
talking
morse code.
they grunt to communicate
Boats and gold
They used smoke signals to communicate with one another.
a wolf communicates with one another with it's spine tingling howl