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Rock stars

Some organisms, like some people, have a charisma that just can't be explained. For me, the sea palm (Postelsia palmiformis) has always been one such organism. Maybe part of its charm is the fact that it's not very common; it lives on rocky outcrops on exposed outer coasts, which aren't the easiest places to get to.

See? That's a clump of Postelsia way out there in the center of the photo.

Rocks covered with olive-green seaweeds in the foreground and ocean in the midground, under a cloudy sky
Algae-covered rocks in the intertidal at Pigeon Point
© Allison J. Gong

The tide was pretty good (-0.9 feet) so I figured it was worth working my way out there. I had a wishlist of critters to collect, but they would be pretty easy to find, and I had time to spend in the low intertidal. The algae are still going strong, although I did see some signs of senescence in some of the reds. The Postelsia, on the other hand, were in great shape.

Group of palm tree-shaped olive-green seaweeds attached to a rock in the intertidal.
Small stand of sea palms (Postelsia palmiformis) at Pigeon Point
© Allison J. Gong

Despite its beautiful olive-green colors, Postelsia is a brown alga in the phylum Ochrophyta. It is in the same order (Laminariales) as the large canopy-forming kelps Macrocystis pyrifera and Nereocystis luetkeana. However, Postelsia gets to be only about a half-meter tall. It has a thick, flexible stipe and a cluster of thin blades at the top of the stop, which give it the palm tree appearance. Postelsia's hapterous holdfast does what it says on the label—it hangs on tightly to the rock. In fact, the rock often fails before the holdfast does, and when Postelsia washes up onto the beach it often has bits of rock (or mussel or whatever) still in the grip of the holdfast.

And it turns out that Postelsia is one of the many photogenic seaweeds. This morning it was doing the '80s hair band thing. Especially when photographed from the vantage of a front-row groupie.

Postelsia palmiformis rocking the joint at Pigeon Point
© Allison J. Gong

So that's the organism that captured and held my attention this morning. The algae don't get nearly the appreciation they deserve, even among fans of the rocky intertidal. Maybe shining a light on them once in a while is something I can do to fix that.

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