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Sunday, May 24, 2015

Skin deep

Okay, are you ready for a mystery close-up?


Although it's tricky, there's a clue near the bottom of the image above.

Here's a slightly different region:



And now I'm going to zoom in on the "clue" (below):


Any guesses?

The clue shown above is a barnacle.  And perhaps you can tell that it's embedded in the skin of a mammal.  So now you have to think about what type of marine mammal would have barnacles living on it?

The picture below provides the answer:


This Gray Whale (Eschrichtius robustus) washed up on the southern end of Portuguese Beach on 23 May 2015.  It was ~31 feet long.

Being a big fan of barnacles, I took a few minutes to research the identity of this species.  It turns out that there are some really interesting facts about it.

The barnacle is Cryptolepas rachianecti.  It only grows on Gray Whales!  The scientific name alludes to that fact, if you know that Gray Whales used to be called Rhachianectis glaucus.  The genus, Cryptolepas, basically means "hidden barnacle" I'm assuming it refers to how most of this barnacle is hidden below the whale's skin.  See illustration below:

From Pilsbry, H.A.  1916.  The Sessile Barnacles (Cirripedia) contained in the Collections of the U.S. National Museum; Including a Monograph of the American Species.  Bulletin of the U.S. National Museum (No. 93).


Here's a picture of what Cryptolepas looks like when you can see all of its plates because it's no longer embedded in the whale's skin (view from above on left, view from below on right):

From Pilsbry, H.A.  1916.  The Sessile Barnacles (Cirripedia) contained in the Collections of the U.S. National Museum; Including a Monograph of the American Species.  Bulletin of the U.S. National Museum (No. 93). 


Because very small barnacles (2-5 mm across) are seen on north-bound whales (there are some in the skin pictures above), it's thought that Cryptolepas reproduces while the whales are in Baja.  This makes sense for the barnacle, since aggregations of whales would make it easier for the swimming barnacle larvae to find hosts.

And Newman (in Intertidal Invertebrates of California, 1980) suggests that the position of the barnacles being flush with the surface of the whale's skin is "a valuable adaptation, since gray whales have been noted to rub against objects on the sea floor and near shore."

 Quite a tale from a barnacle and a whale!



P.S.  Scientists from the California Academy of Sciences think this whale was attacked by Orcas.

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