Medium sized. Carapace broader
than it is long. Two powerful claws. Rear legs pointed for gripping on
Brown. Some specimens about 5% of adults are green. Juveniles in
a mixture of colours.
Swimming Crab, Necora puber.
Juveniles are often patterned
like this one from Penllech
Beach on the Lleyn Peninsular
Eggs released during the
spring mostly, but crabs 'in berry' present in all months. Young particularly
abundant on the shore in June.
photographs (external site)
prior to mating. The female crab is underneath.
© by Chris Rowe
large flap (broader abdomen) of the female crab used to hold the eggs
Abundant intertidally in
spring, and present on the shore throughout the year. Estuaries and
brackish water, rivers, during the summer only. Most widespread of all
medium-sized British crabs
Parasitic barnacle Sacculina
Worms. Mollusc flesh, small
gastropods, small crabs, algae, carrion and almost anything it can catch.
top photograph shows this crab examining a Dogwhelk,
lapillus, a gastropod that is rarely eaten because the shell is too
thick for the claws to crack.)
October 1999, a medium-sized Shore Crab was observed eating a young
(first year) 30 mm Rock Goby, which were frequent
under rocks on Kingston beach.
All British coasts.
Natural distribution further
afield: Norway to Mediterranean and tropical Atlantic coast of North Africa.
Naturalised: as expected
for such a hardy crab, it has spread across the Atantic to the American
side, and probably further afield. I would not be suprised to see it spread
to the southern hemisphere as an unwelcome addition. It could displace
native crabs in estuaries and the adjacent seas and coasts.
Temperature amplitude: 4
- 28° C (and greater).
maenas, or European Green Crab (Shore Crab??) has slowly been making
its way northward along the pacific coast of the US for the past decade
or so. C. Maenas was spotted in Washington state (northwest
corner of cont. US) just a few years ago, and the ecology of that area
is such that it could decimate Washington's mollusk and oyster populations
if it establishes itself.
David Scripps (Minnesota).
that can swallow it, depending on size and location.
In the English Channel they
are eaten by Bass and gulls, Laridae.
Not larger crabs usually.
In June, in the River
Adur estuary, Sussex, England, the juvenile crabs are at their maximum
They often get into fights
with its own kind. It may lose claws in these fights, and many (up to 5%)
adult crabs on the shore have missing claws or smaller claws regrowing.
do crabs walk sideways?
cycle in Crustacea
Only in fresh and brackish
water during the summer when the water temperature is warmer. Unable to
in the colder winter water and the crab returns to the fully saline sea.
In summer, the crab likes
to leave the water (rocks above the waterline in aquaria) and take in atmospheric
oxygen. It is a great escape artist in captivity.
of Oxygen at different temperatures (Ref.)
a high spring tide, a Little
Egret was observed fishing in the shallow
water and capturing a morsel every three minutes or so. At a distance itwas
difficult to see what it was actually capturing in its long black beak,
but on at least two occasions it looked like small Shore
Crabs, Carcinus maenas, that tried
to wriggle out of its beak without success.
maenas, were observed dying in isolated pools in Widewater
by Derek Neate (FOWL)
low level (0.27 metres) of the lagoon, the patch of water by the inlet
pipe became isolated from the main body of water. In this puddle the salinity
was recorded at a hypersaline 42.8‰ after two weeks of warm weather (air
temperatures over 24° C and over 27° C) and a water temperature
of 30.2° C. The main body of the lagoon registered a salinity of 37‰.
(The conditions were favourable for evaporation.)
by John Knight (WSCC)
two events are probably connected. In June (in Sussex) the Shore
Crab moves in estuaries and into lower salinity
water than the sea. In water temperatures of over 28°
C or with a salinity over and above natural
seawater at about 34.5‰
crab has been known to leave the water and perish if it is unable to find
a favourable niche. (The conditions are outside its natural amplitude for
Crabs, Cancer pagurus
will attack and kill Shore Crabs in aquaria
and they will occur together in the wild.
gammarus, will quickly kill and eat Shore Crabs in captivity. They
will meet occasionally in the wild, but not all that often.
Carcinus maenas were
present in small numbers at Goring (near
West Sussex, including a couple carrying the parasitic barnacle Sacculina
by Chris Everson
Hamblett at Adur World Oceans Day 2000
female Shore Crab in the picture called "Sandy"
weighed 78.81 grams alive on 20 June 2000. The carapace measured 70.61
mm wide. (Imperial 2.78 oz, 2.78 in.). It died about a year later without
year in the delightful coastal village of Walberswick in Suffolk, The British
Open Crabbing Championship is held.
The heaviest crab known was
the winner of the Walberswick
Crabbing competition in 1981 which weighed
in at 7.25 oz (205.5 grams).
Crabs of over 3 oz are caught every
year, crabs of over 4 oz are prize
winners and crabs of 5.25 oz have been
caught. The second heaviest Walberswick Shore Crab was caught on 6
August 2000 and weighed nearly 7 oz.
Mon, 27 Nov 2000 09:52:56 +0100
Per-Olav Moksnes <email@example.com>
[CRUST-L:561] Summary: Carcinus max-size
you to all who responded regarding the maximum size in Carcinus maenas.
not yet received any reply that confirms that a Carcinus larger
than 100 mm CW has been collected.
Jensen from University of Washington reported
that Carcinus close to 100 mm CW have been caught in Bodega Harbor,
California (the largest confirmed was 96 mm). Wim Vader from Tromsø
Museum in Norway believe
Carcinus grow larger than 100 mm in northern
Norway, but it has not been possible to confirm this yet. I also
heard some rumors
very large Carcinus in Southern Australia, but I have had no replies
from down under.
look through the literature produced the following list of unusually large
Reference Max CW
(Munch-Petersen 1982): 75 mm
England, USA (Ropes 1968): 80 mm
USA (Cohen 1995): 85 mm
(Zeidler 1988) 85 mm
the 100 mm CW beast caught in Sweden last month appear to be the largest
reported Carcinus maenas.
of Marine Ecology
Marine Research Station
quoted size = 86 mm carapace breadth [which doesn't sound very big
me, 3.4" in imperial units - Pete], but usually less. Terminal ecdysis
can be any time from ~60 mm. (from 'Biology
of the Shore Crab')
Studies Council Publications
The Field Studies Council
publish a special booklet on the Shore Crab.
They also publish an excellent
guide called "A Key to the Crabs and Crab-like Animals of British Inshore
Waters" by John & Marilyn Crothers.
ISBN 1 85153
of the Shore Crab Carcinus maenas (L)" by J.H.Crothers
The Background - Anatomy, Growth and Life History - reprinted from Field
vol 2, no.4, pp 407-34 (1967)
The Life of the Adult Crab - reprinted from Field Studies vol 2, no.5,
Studies Council, Preston Montford, Shrewsbury SY4 1HW
Information wanted: Please
send any unusual records of this crab, with location, date, who discovered
it, how it was identified, prevalence, size, whether 'in berry', common
name and any other details to
Project EMail Glaucus@hotmail.com.
All messages will receive
Thumb (Marine Aquaria)