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Saturday, March 31, 2012

Toothy

You're not going to believe this.  I found what I thought was a dead shark on the beach.  I turned it over to get a closer look at the teeth, and it tried to bite me!


No, just kidding — Happy April Fools' Day!


But I did encounter the head of a shark washed up on the beach, most likely a Leopard Shark (Triakis semifasciata).  Here are photos from above and below (taken on 30 March 2012).  Note the black bands and spots above, and the large nares (nasal openings) in front of the mouth.



Leopard Sharks are locally common in Bodega Harbor and Tomales Bay.  They feed on benthic invertebrates, e.g., crabs, shrimp, clams, and innkeeper worms.  As adults, they measure about 4-5 feet long.  They give birth to live young (~8 inches long) during the spring/summer season (primarily in April and May), often in eelgrass beds.

I've read that Leopard Sharks are sometimes eaten by Great White Sharks (Carcharodon carcharias).  Great Whites are known to spend time in the Bodega Bay region.  Here's a tooth from a Great White that I found on a local beach in 2005.  It's worn like sea glass, so the serrations along the edges aren't as visible in this scan (although you can still feel them on the tooth).


The genus, Carcharodon, means sharp or jagged tooth.  White sharks are impressive apex predators.  They can reach 20 feet in length and may weigh over 5,000 lbs.  Not kidding this time! 

1 comment:

Anonymous said...

Hi Jackie, just wanted to let you know that we used this old post of yours to determine that I was bitten by a leopard shark last Saturday, 5/23, at Chicken Ranch beach in Tomales bay. The photos of the teeth and mouth matched up almost identically with the marks on my leg. The bite was relatively minor with a small amount of bleeding but very clear teeth marks. Your photos ended a lot of speculation and guessing. Thanks so much!
Lisa Ludwigsen
lisaludwigsen@att.net