Fact 1: Echinoderms use pheromones to communicate with each other.

Fact 2: Ascothoracican barnacles attach to echinoderms or corals.

Given the two facts above, answer the question "corals use what to communicate with each other" with the following options: 
- Energy
 - pheromones
 - kinetic energy
 - produce light
 - heat produced
 - heat energy
 - Chemical energy
 - sound


 

  pheromones       