Surprise!

 

Spiny Lobster (Panulirus interruptus) molt, washed up on Bodega Head, 19 September 2017

Although we had wondered if we'd ever find a Spiny Lobster in Bodega Bay, we were surprised to look down and see this on the beach tonight.

Spiny Lobster are a southern species — they are primarily found south of Point Conception, and they're most abundant off the central coast of Baja California, Mexico.  During El Niño years, they may be observed north to Monterey.  Since about 2011, molts have been discovered occasionally in San Francisco (Crissy Field) and Bolinas (Agate Beach).

There is a 2001 record for a post-larval stage Spiny Lobster in Bodega Harbor, but to our knowledge, this is the first record of an adult Spiny Lobster molt in Bodega Bay, and therefore the northernmost record for a Spiny Lobster molt on the West Coast!

Spiny Lobsters can reach a carapace length of ~44 mm in 2 years.  The molt we found was missing the carapace, but we can still come up with an estimate — see photo with ruler below:

 

Here's some rough, but interesting guesswork.  The carapace on this individual might have been ~50 mm long...which is a potential match for a 3-year old lobster...which is a potential match for a lobster that settled in northern California during the warm-water anomaly ("The Blob") in 2014.  We have some research to do on these measurements, but it's interesting to think about when the lobsters might have arrived on our coast.

We'd be very interested in any other sightings of Spiny Lobster molts from Point Reyes north, so let us know if you spot any washed up on the beach (and please take a photo)!

P.S.  I was curious about the scientific name.  The specific epithet "interruptus" comes from the interrupted groove on each abdominal segment.  Below, note the gap (white arrow) separating the grooves that run through the middle of each abdominal segment: