Echinoderms use pheromones to communicate with each other, and modern echinoderms include starfish and sea urchins. Given these facts, how do starfish communicate among the following options:
- huddle together
 - sound
 - interact
 - Vibrates
 - wave in air
 - during the day
 - Decibels
 - Pheromones


 

        Pheromones 