Intertidal Star Clusters

On many occasions I’ve noticed Ochre stars (Pisaster ochraceus) gathered up together in semi-protected rock crevices. It’s easy to imagine they do that because it’s a good place to stay together and have protection from pounding surf when thee tide is at that level, and the effects of drying when the tide drops lower. However, on a recent trip to John Brown’s Beach, I noticed several star clusters on the flat gravel beach near the gazebo dock. I am not sure why these have gathered like this, protection from the effects of drying seems plausible. However, it amuses me to think they might also be social creatures who like to get together for a chat (or whatever passes for such in the ochre star world).

Ochre Star cluster questions:

  • What is the purpose of their clustering?
  • How do they find each other and gather up?
  • Do the same individuals end up in the same group?
  • How long does the gathering last (more than one tide cycle)?
  • How far does an ochre star travel over the course of its life?
  • (How) Do ochre stars communicate with each other?

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