ID : Broad-clawed Porcelain Crab?

[Andrew C]

Hello,

I have uploaded a few images of a crab species found at Thurlestone Rocks that I believe to be a Broad-clawed Porcelain Crab yet it does not match my literature very well so I want to ask what others think of this one please?

Regards,
Andrew.

[The Woodman]

I think you're spot on there, Andrew. A nice find.

[Andrew C]

Brilliant, thanks ever so much.

Regards,
Andrew.

[Wild-Woman]

Good to see some crabs coming up for Id. Nice find.

[Marineboy]

Yes, I agree, it is good to see crabs making an appearance. This, as The Woodman says, is the broad clawed porcelain crab, Porcellana platycheles. (The long clawed percelain crab is completely smooth, whereas this one is fringed with hairs).
My 1996 copy of Collins Sea Shore of Britain and Europe offers only a poor representation of these crabs, so its easy to get thrown by published literature.
Both species can be found crawling flat against the underside of a stone on the lower shore, often together. They are primarily filter feeding crabs, taking suspended organic matter from the water.
Another notable feature of both species is the apparent absence of the fourth pair of walking legs. Crabs have two claws up front, and eight walking legs - same with this species, but you will not see the fourth pair of legs as they are so small and thin, and held within the branchial chamber - held internally, where the gills are - so appear to only ever have three pairs of walking legs.

[Andrew C]

Originally Posted by Marineboy

Yes, I agree, it is good to see crabs making an appearance. This, as The Woodman says, is the broad clawed porcelain crab, Porcellana platycheles. (The long clawed percelain crab is completely smooth, whereas this one is fringed with hairs).
My 1996 copy of Collins Sea Shore of Britain and Europe offers only a poor representation of these crabs, so its easy to get thrown by published literature.
Both species can be found crawling flat against the underside of a stone on the lower shore, often together. They are primarily filter feeding crabs, taking suspended organic matter from the water.
Another notable feature of both species is the apparent absence of the fourth pair of walking legs. Crabs have two claws up front, and eight walking legs - same with this species, but you will not see the fourth pair of legs as they are so small and thin, and held within the branchial chamber - held internally, where the gills are - so appear to only ever have three pairs of walking legs.

Thanks. I did find my arsenal of literature a bit unhelpful on this one.

I have since discovered that Coryton's Cove at Dawlish looks pretty good for rock pooling. With the tides looking pretty low later this week I may try this spot. Have you ever been here and how have you got on?

Regards,
Andrew.

[Marineboy]

Originally Posted by Andrew C

I have since discovered that Coryton's Cove at Dawlish looks pretty good for rock pooling. With the tides looking pretty low later this week I may try this spot. Have you ever been here and how have you got on?

Regards,
Andrew.

I have had an eye on the tides too; Thursday, Friday Saturday this week seem quite good.
I don't know Coryton's Cove but like you I would welcome some rockpooling info if anyone has any.
I am hoping to get out one day towards the end of the week as I just happen to be off work with a reasonable low tide late mornings! I could have a look at Coryton's Cove, but I was going to go a little further south to explore Wembury - Thursday, Friday or Saturday depending on the weather. Any thoughts of where best to park and where to go, either/both locations would be good. Thanks.

[Andrew C]

For Wembury, there is really only one spot for parking and that is the National trust car park which overlooks the rocks so you can watch the tide begin to drop as you warm up with a cuppa. A cracking spot.

As for Coryton's Cove. Parking is not free unles you walk a long way in from out of town. The parking for here is right on the sea front by the railway line. Walk along the sea front to the southern end and carry on past the small outcrop and you will see a rocky sandstone beach below some beach huts.

For my money, I would prefer Wembury. We could both report back on how we do and compare findings.

Regards,
Andrew.

[Marineboy]

Sounds good. To be honest I had promised myself a trip to Wembury.
If you do go to Coryton, when you are done on the lower shore, check out the middle and upper shore on your way up the beach at Coryton - MarLIN have the Mediterranean marbled rock crab Pachygrapsus marmoratus recorded from around the Teignmouth/Devon area, and it might just show up at Dawlish. I will certainly do the same at Wembury. It may be that it can be found around the damp bases of rocks, grazing on algae, out of the water.
Pachygrapsus marmoratus - Wikipedia, the free encyclopedia

A cuppa at Wembury - looking forward to it already!

[Andrew C]

Thanks, I will certainly keep an eye out for Marbled Rock Crab. Looks like a pretty distinctive crab.

Regards,
Andrew.