Slender Crab in Richmond

[Red Fish]

Something for the Misc. category. Someone pulled this up and we were all wondering what kind of crab it was so I brought it to this forum.
As I was logging in, I noticed the featured photos currently on the home page of crabs (one of which displays a slender crab).

So what’s the question then?
Okay, Ken et’ al, how common are slender crab in SF Bay?

 

[SC McCarty]

Hi Red Fish,

While it appears to be a Cancer crab (those that are or used to be in the genus Cancer), it is not a slender crab:

"Distinguishing Characters: White-tipped pincers on the claws. The tops of the claws are sharp-edged, with two or three prominent teeth, but these edges are not sawtoothed as in the market crab. The last three joints of all the walking legs are hairless. Compare particularly the last three joints of the last pair of legs with those of the Dungeness crab (Figures 1 and 2), the only other crab of this group which has white-tipped pincers, and with which this crab may be confused. Since the slender crab seldom exceeds a width of 3 inches across the back, it can only be confused with the young of the Dungeness crab. The tip of the last segment of the tail flap is pointed in both male and female. "​

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Note the white tipped claws, short antennae, and more, smaller spines on the carapace. The purple legs are also common, but others have brown.

Steve

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[Red Fish]

Hi Red Fish,

While it appears to be a Cancer crab (those that are or used to be in the genus Cancer), it is not a slender crab:

"Distinguishing Characters: White-tipped pincers on the claws. The tops of the claws are sharp-edged, with two or three prominent teeth, but these edges are not sawtoothed as in the market crab. The last three joints of all the walking legs are hairless. Compare particularly the last three joints of the last pair of legs with those of the Dungeness crab (Figures 1 and 2), the only other crab of this group which has white-tipped pincers, and with which this crab may be confused. Since the slender crab seldom exceeds a width of 3 inches across the back, it can only be confused with the young of the Dungeness crab. The tip of the last segment of the tail flap is pointed in both male and female. "​

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View attachment 917 View attachment 918​

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Note the white tipped claws, short antennae, and more, smaller spines on the carapace. The purple legs are also common, but others have brown.

Steve

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The size was right. The color variation is okay. The crab perhaps had some white on the inside of the claws (from the other photo I have). I cannot count 10 points on the shell.
What kind of crab is it?

 

[SC McCarty]

The size was right. The color variation is okay. The crab perhaps had some white on the inside of the claws (from the other photo I have). I cannot count 10 points on the shell.
What kind of crab is it?

Hi Red Fish,

I only saw the first photo on your original post. The first photo has far fewer points than any than any that I have found information on. I wonder if it is an exotic. I am attaching a file describing common Cancer crabs.

The significant white on the claws, is the tips. Most of the cancer crabs have black tips. Only the dungeness and slender crabs have white tips. We can't see the tips of the claws on the second photo, so we can't rule out slender crabs, but the points seem too prominent to me.

Steve

 

[Red Fish]

Hi Red Fish,

I only saw the first photo on your original post. The first photo has far fewer points than any than any that I have found information on. I wonder if it is an exotic. I am attaching a file describing common Cancer crabs.

The significant white on the claws, is the tips. Most of the cancer crabs have black tips. Only the dungeness and slender crabs have white tips. We can't see the tips of the claws on the second photo, so we can't rule out slender crabs, but the points seem too prominent to me.

Steve

The second photo is the one Ken Jones has posted on the home page as a slender crab. I have one other photo of the original crab where one claw is opened and you can see a little white on the inside. As I mentioned, I can’t count 10 points on the original crab photo (one of the requirements for a slender).