Why is a negative low tide important? Because the tidal zones are divided into four areas and Zone 4 is only exposed when there is a negative low tide. Zones 1 and 2 are called the Splash Zone and the High Tide Zone respectively and here you will see the periwinkles, barnacles, and limpets. These rocky areas will be dry at least for half the day. In Zone 3, there is much more to see including the starfish, anemones, mussels, and crabs. This is the Mid Tide Zone and it is dry for about a quarter of the day. Finally, in Zone 4, the Low-Tide Zone, you find the "treasures" including the octopi, sea urchins, sea hares, etc. This special area is only exposed every few weeks and not always in the daylight. (I got my description of the zones from the map handed out to us at the gate.)
We were pretty lucky. The weather was foggy and very cold but it was not windy. The sun set early behind the fog bank out over the ocean, but we were able to see some pretty good stuff before we had to leave and climb back up the cliff. What impressed me was the many colors that we saw—oranges, green, blue, and purple. The anemones, the starfish, and the one sea urchin we found were especially colorful. If you want to learn more about these fascinating creatures, Genny Anderson of Santa Barbara City College has an online course on the tidepools of California with some spectacular photos. I am indebted to her for the information given below.
Pisaster ochraceus, also called the ochre sea star.
California mussel, Mytilus californianus. Don't they look like they are smiling? Maybe that's where the expression "happy as a clam" came from.
It is interesting to look at the different color patterns on the tentacles and oral disks of these starburst anemones. The various shades of green come from a combination of the natural color of the anemone and from green-colored symbiotic algae that grow in their tissues. Anemones found under rocks or in the shade have little symbiotic algae so are generally very pale. The various striping on their tentacles is genetic and serves to show how each is unique.
Sea urchin S. purpuratus, also called 'purps.' There is a piece of kelp stuck to this fellow. That is their favorite food.