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 Crab Database

  South-claw Hermit Crab
 
Diogenes (Photograph by Paul Parsons)
Common Name(s):
South-claw Hermit Crab

Scientific Name:
       Diogenes pugilator
Family:
Usual Size:  cm 

                    Photograph by Paul Parsons (Aquapix)
Identification:
 
 
 
Diogenes (Photograph by Andy Horton)


The major larger claw is always on the left side nearest the apex of the adopted shell when viewed from the front. 

The Hermit Crab on the left is Diogenes pugilator with the major claw on the left.

Similar species: Pagurus bernhardus
Pagurus cuanensis  (CD-ROM ONLY)
Breeding: 

 
Habitat:
Strandwerkgroep file
 
     
Food:

Bionomics:
 

Diogenes pugilator (Photograph by Andy Horton)
Diogenes
Range:

Additional Notes:
 
 

More Information

I was interested in your recent find of a couple of Diogenes. It is a species with an interesting distribution and interesting habits. Some years ago I supervised at least two summer MSc projects on it. Since I think MarLIN have yet to do a page on it I thought you might be interested in a few comments.

The distribution round Britain and Ireland is or was generally southwestern. In the Irish Sea it comes up the Welsh coast as far as the
west coast of Anglesey. Here it occurs commonly on certain flat slightly
exposed beaches and just offshore from them. For example at Aberffraw I can
find 20 - 50 in a few minutes if I go at an evening LW in July and August
when they are active and out of the sand. The distribution is clumped -
possibly sexual activity rather than fighting for shells. Most are only in
ankle deep water at this time so are easy to see. Although quite abundant
on the right sort of beach on the west coast of Anglesey they do not as far
as I know extend round to the east side of the island. There are no records
from the east coast of Ireland but there are on suitable beaches in
Cardigan Bay, Carmarthen Bay and Gower. Interestingly, the illustration in
Bell's "Stalk-eyed Crustacea" is one from Rhosslli in Gower. 

Virtually all the beaches where I know of them in Wales are flat beaches
with medium / fine sand and where the waves spill rather than curl when
breaking. Diogenes burys rapidly and our hypothesis is that the south-paw
arragement of the chelae is connected with burying. They seem to use the
major chela as an anchor to stabilise the shell while digging themselves
into the sediment. In some circumstances they can be seen using the major
chela in such a way was to limit the rolling of the shell in the wave
swash. If you have Pagurus and Diogenes together in similar shells, the
Diogenes become active after disturbance much more quickly. An adaptation
to re- bury quickly.

Concerning the distribution in the SW and English Channel. The MNCR
database did not have any records from the north side of the SW peninsula,
not counting the Scillies, but on the S side they had them as far east as
Lyme Bay. Like several other things they did not normally seem to get past
Portland Bill. This makes your Sussex record particularly interesting. On a
beach near Plymouth (name forgotten) thety were sufficiently abundant to be
used as test animals for dispersant toxicity at the time on the "Torrey
Canyon". However on the French side of the Channel they seem to be abundant
at least as far as the Straits of Dover. I know less of the French
literature, but in August this year we were doing work in the Channel on
fish habitats and found them abundant in a small mesh beam trawl at a depth
of 17m off Le Touqet. As in North Wales most were in Hinia shells.

For the record, they were found in a few places on the west coast of
Ireland as far north was Donegal in the Irish equivalent of the MNCR. These
are the furthest N I know of in the British Isles.

Whereas most Britsh records are from beaches, off S Spain and Portugal they
seem to be common subtidally on sandy grounds to judge from the literature
on their reproduction etc I have turned up.

Naturally I would be interested in any more you find and in the types of
area they come from. 

Ivor Rees
 

Reports:

6 October 2002
The low tide on Lancing beach revealed my very first discovery of the South-claw Hermit Crab, Diogenes pugilator, on the Sussex coast. This Hermit Crab was discovered in knee depth water in the sandy shallows below the low tide mark on the equinoctial spring tide, receding below Chart Datum. They occupied the empty shells of the Netted Dogwhelk, Hinia
Full Report
 
 
 
 
 

Links: 

Hermit Crabs for the younger student (NE Atlantic species only)
 
 

Information wanted: Please send any records of this crab, with location, date, who discovered it, how it was identified, prevalence, common name and any other details to 
Shorewatch Project EMail Glaucus@hotmail.com. 
All messages will receive a reply. 
 
Shorewatch Project

 

FIVE KINGDOMS TAXONOMIC INDEX TO BRITISH MARINE WILDLIFE
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