Ochre sea star is the species of starfish that used to be common in the rocky intertidal zone around Pacifica. Despite their English name, these starfish come in a range of colors: ochre, lavender, orange, brick red.
In the vertical stratification of intertidal invertebrates along the rocky shore, these sea stars are normally found in the zone just below the band of California mussels. As the sea stars prey heavily on the mussels, their vertical distribution more or less defines the lower limit of the band of mussels.
Ochre sea stars used to be so common that at this time of year, several wintering glaucous-winged gulls specialized in feeding on them, spending most of their day seeking them out and then trying to swallow them.
Recently, a mysterious starfish die-off has hit many areas along the West Coast of North America, from Alaska to Southern California, killing ochre sea stars as well as other species. The die-off is caused by something called sea star wasting syndrome, but the pathogen causing this wasting and die-off is still unknown.
As I had not seen any reports from the Pacifica area, I took advantage of low tide December 5 to walk around the rocky shore of Rockaway Headland to see if our local ochre sea stars have been impacted by the mysterious die-off.
Unfortunately, I found that they have. I checked many large rocks that I know used to be covered with dozens and dozens of these starfish, but despite searching along a couple of hundred meters of shoreline, I was unable to find a single sea star.
The top photo (above) shows what it used to look like, with ochre sea stars crowded along the lower edge of the band of California mussels. This photo was taken two years ago. The bottom photo was taken December 5, 2013 in the same general area. The lower edge of the band of California mussels is still well defined, showing where the sea stars used to be, but not a single sea star is to be seen anywhere.