Puget Sound King Crab

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The largest crab we see in the San Juans.  Not edible like the Alaskan king crabs, or at least I’ve never heard of them being harvested and eaten.

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Tim Dwyer, amazed at how large Puget Sound king crabs can get.  Despite the large, heavy claws, these crabs have never pinched us.  When we handle them they tend to tuck all their legs into the body.  This particular crab was scrabbling to find something to crawl away onto, not trying to menace the camera.

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Closeup of the face.  The spiky bits are part of one of the two pairs of the antennae.  You can see the other pair of antennae just above the spiky bit on the left.  The eyes are dead center, on either side of the triangular rostrum (looks like a nose).  The blue rectangular pieces are the 3rd maxillipeds, which help chew up food.  There are five other pairs of mouthparts, including the 2nd and 1st maxillipeds, the 2nd and 1st maxillae, and the mandibles.  All are involved in chewing and shoving food back into the mouth.

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Lopholithodes mandtii is an Anomuran crab, more closely related to the hermit crabs than to shore crabs or Dungeness and red rock crabs.  How to tell if a crab is an Anomuran or a Brachyuran (the group that includes typical crabs)?  Count the number of walking legs, including the pincers.  If it has 4 pairs it’s an Anomuran.  If it has 5 pairs, it’s a Brachyuran.  Another way to tell is to look at the abdomen (the shield on the ventral side of the crab).  If it’s asymmetrical it’s an Anomuran.

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Color in adults tend to be various shades of orange or red, with blue highlights.

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Juveniles are bright orange to red.

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Despite the bright coloration shown in these photos, Puget Sound king crabs are almost perfectly camouflaged.  The bright oranges and red are nearly invisible at the depths these crabs live (we tend to see them at 20m or deeper).  Without the bright colors, they look like all the other rocks they crawl over.  They only pop out when we use flashlights.

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