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Saturday, January 3, 2015


During a short excursion to the rocky intertidal zone during the low tide tonight, I was excited to encounter a species that I've been looking for on Bodega Head since we moved here in 2005.  Although they're known to be in northern California, I'm starting to wonder if their abundance in this region might be dependent on water temperature.

Above is the first Hopkins' Rose (Okenia rosacea, formerly Hopkinsia rosacea) that I found today.  Since I hadn't seen this nudibranch on Bodega Head before, I was surprised to see a second individual soon after: 

Then I started scanning the nearby rocks.  Once I developed a search image for these pink blobs, I found quite a few more.  In a 2-meter span, I counted 15 nudibranchs!

Some individuals were very small (less than 1 cm long):

The largest were ~2.5 cm (~1 inch) long: 

I mentioned the possibility that the presence of this species here might be related to warm water.  Up until just recently, ocean temperatures were still 14-15°C (57-59°F) off Bodega Head — extremely unusual for this time of year.  I don't have enough experience to know if other sightings of Hopkins' Rose in this area have been correlated with warm water, but I'd love to hear from anyone who might have thoughts about this.

If you'd like to learn more about this beautiful nudibranch, click here to review the post from March 2014 when I wrote about them after a field trip to Monterey Bay.

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