Exploring the Pillar Point Tide Pools

Exploring the Pillar Point Tide Pools

By: Rachel Wong


Rachel with sunflower starOn December 12, 2012, several MSI staff members and friends headed out to the tide pools at Pillar Point in Half Moon Bay. A few of us showed up early (around 1 PM) to explore the beach. We were looking for new animals to add to our aquarium. After scouting out bits sea weed, picking up pieces of trash, and dodging the cold waves, we finally came across something interesting. Our aquarist, Jesus, was lucky enough to spot a thornback ray (Platyrhinoidis triseriata) that was cleverly camouflaged against the sand in the shallows. After a few more moments of excitedly scanning the sandy beach, we at last found something we could collect. From afar, the organisms looked like a small, rocky mound, but upon closer inspection we discovered that the smooth-looking rocks were in fact two moon snails. Moon snails (Lunatia lewisii) are large, palm-sized, slimy snails that like to live on sandy beaches. This was an incredibly lucky find, since it is rare to find these organisms because they tend to bury themselves in the sand. After we excitedly scooped up a moon snail from the beach, we moved down to the rocky intertidal so that we could explore the tide pools.

Shortly after making our way out onto the tide pools, we met up with our entire group and we began exploring the wonders of the rocky shore. At approximately 3:45 PM the low tide was at -1.6 feet, and we made our way out across the rocks to explore as much as we could before nightfall. It is always exciting being out in the tide pools, slipping across the algae, and watching the marine life glide around in the small pools of water. We wandered all the way out to the urchin beds, the furthest point from the beach, and we 124watched the waves as they pounded against the rocks. While keeping a watchful eye out for rogue waves, we pulled our hands through great swathes of sea weed, gently flipped over rocks, picked through mussel beds, and peered into dark crevices in search of interesting creatures. We were excited to find a few clingfish (Gobiesox maeandricus), which we added to our aquarium collection. These fish are one of my favorite tide pool fish because of their adorable, teardrop body shape and their unique adaptation. The cling fish has fused pelvic fins that form a single suction cup. This suction cup can be used to hold on tightly to rocks, bracing the clingfish against strong waves that threaten to tear them away from the safety of rocky hiding spaces.

sunflower starIn addition to finding the clingfish, we scooped up a few sea stars such as the orchre star (Pisaster orchraceus), the bat star (Patiria miniata), and my favorite garlic-smelling sea star, the leather star (Dermasterias imbricata). We were very pleased with our findings, and we are happy to add new organisms to aquarium so that we can share the wonderful marine life of the rocky shore with our visitors. We also saw quite a few interesting creatures including the brightly-colored sea lemon (Peltodoris nobilis), top snails (Calliostoma spp.), a strange type of tunicate called sea pork (Aplidium stellatum), our lovely local encrusting coralline algae (Melobesia mediocris), and a large, gooey purple sunflower star (Pycnopodia helianthoides).

Every time I go to the rocky shore I discover something new and wonderful. I feel like the ocean always teaches me something, or inspires me to explore and ask more questions. However, if we want to be able to explore this wonderful marine habitat, we must be sure to protect it. On this particular visit, as a result of all the recent rain and runoff, we found quite a bit of trash along the beach and in the tide pools. This is a clear reminder that we, as stewards of this planet, must always be mindful of our actions and how we can impact natural environments.127

The rocky shore is an exciting and beautiful marine environment that is right in our backyard. If you enjoyed hearing about all of our findings, you should make your way out to the coast and go on an adventure. Hopefully you will get a chance to explore the tide pools with MSI through one of our public events http://sfbaymsi.org/baylines.html. We look forward to seeing you out there.


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