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Wednesday, November 5, 2014

Spinner!

After a short article appeared in the San Jose Mercury News about warm-water species appearing in northern California this year, Mark Kudrav, a naturalist from Pescadero, contacted us to let us know about another interesting species he documented on August 14th: 


Eastern Spinner Dolphins (Stenella longirostris orientalis) are subtropical/tropical species, normally found off Baja, Californiafrom about 24°N and south.  Finding one on Pescadero State Beach (at about 37°N) is quite rare, and perhaps associated with the warm water that extended north along the coast this summer/fall.

Mark said that the dolphin was ~6 feet long.  Spinner dolphins are known for their variable color patterns, but the eastern Pacific subspecies is typically dark.

The dorsal fin is relatively small:



The beak and teeth are notable.  Spinner dolphins are known for having very long, slender beaks (hence the species name, "longirostris") and a lot of teeth.  There are 45-65 teeth in each jaw, one of the highest tooth counts of any marine mammal!


And here's a shot of the flukes and tail stock.  I read that the swelling on the tail stock might be indicative of a male.


Many thanks to Mark for sharing this observation and great photos.  Since I'm still new to California, I don't know how often spinner dolphins show up here, but I thought you'd like to know about this visitor from the south. 

P.S.  For this post, I gleaned some facts from a few web pages: OBIS SEAMAP, American Cetacean Society,  and the Convention on Migratory Species.
 

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