A single orange Pisaster surrounded, mostly, by giant green anemones. The background is mostly crustose corallines
Pisaster and Anthopleura

When the tides fall to their lowest, they briefly expose the rocky shore’s hidden wonders. The most wondrous of those, like the colorful starfishes and anemones, can draw us in (seasoned tidepoolers and first-timers alike) like almost nothing else. Still, it’s not strange at all to surrender to the pull of lesser treasures. For example, I’ve lost track of intertidal time more than once with the nereid worm, Nereis vexillosa. Nereids are polychaetes celebrated for their parapodia (fleshy leg-like appendages), among other impressive characteristics. The one shown below is a familiar resident on Oregon beaches. (Notice its parapodia?) I should caution that while I’m pretty sure it’s N. vexillosa, worms are worms—there are lots of them and lots of look-alikes. Unless you’re an expert, casual field identification is fraught with uncertainty.

When the tides are right in the spring and summer, it’s common to find lots of  N. vexillosa on the shoulders of the mussel beds, where you can experience excellent wormwatching among the barnacles if you arrive by sunrise.

Morning finds the worms out and about, probing and exploring.

Spring and summer are the seasons, if you’re lucky, to see the ripe females’ blue anterior and red posterior body coloration. Enlarged parapodia too! Now that’s a treasure.



  1. Thank you for sharing these amazing treasures you have found in the rockpools! The colourful starfishes and anemones are so beautiful and reminds me of my mom sitting on the rocks watching them! That is in itself a wonderful treasure! The worms are quite a different story, as I am not to fond of them 😀

  2. Great post. It’s easy to be seduced by the attractions of a sea anemone or starfish, or by a crab sidelining itself across a pool. It’s good to be reminded that the not so obvious candidates have an interest too.

  3. Two things tend to keep me from observing these critters… I suppose the primary thing is likely that I’m not likely to arrive by sunrise. But then you’re talking about worms…. ewww! 😫

    1. I completely get that. Two things helped draw me in to these worms. First, they’re active and they have good vision, so they don’t like it when you get close. So the are a challenge to photograph. Second, when is saw the mature blue and red females I was hooked. (The mature worms drop off the rocks for spawning)

  4. Oh dear Steve, I’m going to admit that worms like these ( or any worms for that matter) would not be seen as a treasure to me! But then you probably knew that! Of course they like every creature on earth and in the sea has it’s role to play. I’m glad there are people like you who understand their importance and DO see them as treasures!

  5. Your enthusiasm shines through in this post. I’ve never spent time looking at worms while exploring the beach. I have in my backyard, and I have much gratitude for the worm.

    1. Ticks! Finding the treasure in them is a reach. I’ve got a little tick compassion inside me, but it rarely sees the light of day. Thanks, Ann-Christine.

  6. Love your posts, I was out at low tide at Seal Rock Oregon (just below Newport) and saw a couple of men collecting Muscles (to eat) and others mostly tourists, like me. Saw tiny crab, running for his/her life and alot of worm trails, but unfortunately no worms. Love the outcroppings along the coast, beautiful, lovely place to live. Lucky you.

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