The Crangon allmanni and Crangon crangon are generally sandy towards grey,
but the Pontophilus spp and Philocheras spp - which may well be undergoing
name changes always feature turquoise/green patches - it was our best way of
seperating them when studying trawls.  The small spines on the carapace
(which distinguish the animals) do not show up on photographs and are very
difficult to see with the naked eye.

Regards

Marie Pendle

From: Marie Pendle EM CEFAS <M.A.Pendle@cefas.co.uk>

Crangon crangon

Norwegian Shrimps (Link)


To add to Marie's comments. At sea, in my experience, freshly caught
Crangon allmanni are usually notably more ginger in colour as compared to
the sandy grey of the common shrimp C. crangon. Mixed catches do not happen
very often as they separate by depth, but the two can be quickly split on
the deck of the boat on the basis of colour. By holding C. allmanni to the
light, end on, the diagnostic dorsal groove on the last pleon segment can
be seen with the naked eye even in quite small individuals. The colour
difference between the two Crangon species can sometimes be detected even
in shrimps in fish stomach contents if digestion has not advanced too far.

Ivor Rees
 

E.I.S.Rees         oss058@bangor.ac.uk

On Mon, 24 Sep 2001 21:04:25 -0400, you wrote:

>Shrimps
>http://www.student.uib.no/~st00502/images/gall3/macronor/mac2.html
>
>I have never seen Crangon with colours other than brown changing to sandy
>colour depending on the colour of the substrate or whether it is night or
>day.

I've never seen any Crangon (or Pontophilus) with anything even
resembling that coloration either. Also the habit, sitting on what
appear to be an urchin test, and body shape, to me suggests that this
isn't Crangon. If I was to hazard a guess... Philocheras?

If whomever posted that pic could post more pics of the shrimp that'd
help - it's a nice pic, but I can't make out much detail.

Philocheras, if that's what it is, seem quite rare here in Sweden.
It'd be interesting to know if they really are common in Norway.
 
 

Michael Norén, Doctoral student,
Stockholm University and                      Tel: Int +46 (0)8 5195 5163
Swedish Museum of Natural History,     Fax: Int +46 (0)8 5195 5181
                        "Nihil umquam facile" 

Mike,

I participated in a study of the southern North Sea, English Channel and
Celtic Seas - there is a paper on this study if anyone is really really
interested - surveying epifauna and infauna from marine sites, ranging from
realtively close inshore to quite a way offshore (SW Approaches and central
North Sea)  We found Crangonidae at most sites - including some with almost
50/50 Crangon allmanni/crangon.  All the other species were given the genus
Pontophilus at that time and we found
Pontophilus bispinosus (also Philocheras bispinosus) now Crangon bispinosus
neglectus
Pontophilus echinulatus (also Philocheras echinulatus) now Crangon
echinulatus
Pontophilus fasciatus (also Philocheras fasciata) now Crangon fasciatus
Pontophilus sculptus (also Philocheras sculptus) now Crangon sculptus
Pontophilus spinosus - no name change
Pontophilus trispinosus - no name change
Both of Pontophilus species were present in moderate numbers in the North
Sea, along with occasional C. fasciatus.  C. fasciatus was absent from the
English Channel and Celtic Seas, but all others were found in these areas.
I would infer from this that C. fasciatus may indeed be present up in
Norwegian waters - Smaldon, 1979 gives a distribution from Iceland to the
Mediterranean and Azores and mentions the "blue spots".

Regards

Marie Pendle


  mentions the "blue spots".

Regards

Marie Pendle