Echinoderms use pheromones to communicate with each other, and echinoderms are represented by the starfish. Given these facts, how do starfish communicate with each other among the following options:
- huddle together
 - writing
 - during the day
 - pheromones
 - Chemical energy
 - waving their arms
 - Decibels
 - talking


 

    pheromones     