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Wednesday, December 2, 2015

Olive's in Sonoma County


Tonight I'm very excited to share such a beautiful nudibranch with all of you. 

While conducting surveys on 25 November 2015, Eric spotted two of these Olive's Aeolids (Anteaeolidiella oliviae) in the low intertidal zone at Pinnacle Gulch.

Olive's Aeolid is generally a southern species.  In fact, it appears that it reaches its northern limit in Mendocino County.  Although there were at least two observations of this species in Sonoma County (Coleman Beach and Shell Beach) and one observation in Mendocino County (Fort Bragg) earlier in the year, I haven't been able to find any records further north.  As with Hilton's Aeolid, the presence of Olive's Aeolid in Sonoma County this year may be associated with recent warm water conditions along our coast.

Some of this nudibranch's features are easy to see the orange cerata (projections on its back) and the darker rhinophores (sensory organs).  Here's a close-up of the cerata (below).  Note that they have pale tips.



This next photo also shows the white speckles on the body, and two small black eyes behind the rhinophores.  (And note that the rhinophores, like the cerata, also have white tips.)



Eric was also able to shoot a short video of this nudibranch.  This individual was ~2 cm long.  Because they're rare this far north, we felt lucky to encounter Olive's Aeolid.  We hope you enjoy learning about it as much as we did!

anteaeolidiella oliviae sanford from Jackie Sones on Vimeo


P.S.  CORRIGENDUM (3 December 2015): I updated the distribution description above to reflect a record from Mendocino County.

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