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Latin molluscus = soft

Soft bodied animals with a hard external shell (mussels, winkles, snails), or an internal shell (sea hares, cuttlefish) or have lost their shell in the course of evolution (nudibranchs). Molluscs have a mantle that secretes the calcium carbonate that makes up the shell. They inhabit numerous different environments with a large number living in the sea.

Octopuses and squids have evolved to intelligent mobile forms with complex behaviour.

British species of molluscs found in the seas and estuaries around these islands

Oyster with Chiton (Photograph by Andy Horton)European OysterEuropean OysterEuropean OysterChiton

Class Polyplacophora



The commonest and most widespread chiton found on British rocky shores is Lepidochitona cinerea. On many shores it is the only species to be found.

Chitons Page

Class Scaphopoda

Tusk Shells

Class Gastropoda

Hardy's Internet Guide to Marine Gastropods 
Checklist of European Marine Mollusca
Mollusca of the NE Atlantic & NW Europe on facebook

It is in this class of animals that the typical spiral snail-like molluscs are classified. However, unlike land snails, the marine ones breathe through gills to obtain oxygen from sea water. Gastropods have a feeding organ called a radula.

Subclass Prosobranchia (Marine Snails)  front-gilled snails.
Most of this taxa contain a spirally-coiled shell and a prominent foot on which it crawls around. The foot can usually be retracted in the shell. The opening is called the aperture. They breathe through gills.

Winkles (External)
Mediterranean Topshells, Trochidae

Pages under construction:  Dogwhelks, Limpets, Whelks, Winkles, Topshells

12 January 2001
 Jim Hall discovered the curious lamellarid mollusc called Lamellaria perspicua on a bare boulder on the extreme lower shore (on a spring tide) of Lydstep beach, 3 miles from Tenby, SW Wales.

Order: Vetigastropoda

Family:  Halotidae  (Abalones)

1 May 1998:
Green Ormer Database file

Daniel L. Geigers Homepage  (Malacology)

Triton Whelk

12 March 2005
Stan Breban, a scallop fisherman brought me a Knobbed Triton, Charonia lampas, which he caught in his scallop dredge somewhere in the Little Russel to the east of Guernsey in the Channel Islands.

Knobbed Triton    Richard Lord

The whole animal weighed 541 grams (drained) and had a total shell length of 16.5 cm. It had a shell width of 10.5 cm and a shell height of 7.5 cm. This large gastropod mollusc is expected to find a home in Guernsey Public Aquarium at St. Peter Port.

Report and Photograph by Richard Lord (Guernsey)
on the Marine Wildlife of the North-east Atlantic Ocean Group

16 October 1999
John Shuker from Sark caught a Knobbed Triton, Charonia lampas (L.), to the west of Sark, north of Les Hautes Boues and south of Brehou Island.  (About 2 ° 23 minutes 30 West and 49 ° 25 minutes 30 North).  It measures 222 mm total length. Weight drained 1128 grams.  The specimen is alive.  I took the triton to the Guernsey Aquarium on Monday.  Since receiving the specimen I have spoken with some fishermen.  Maurice Downs, now a sand eel fisherman, says that in the late 1960's during the queen scallop fishery boom he and several other dredge fishermen caught a couple each. I was told that a scallop diver, Richard Keen, picked up a few in the late 1980's or early 1990s.  The Guernsey aquarium kept one for about eight years in one of their tanks.  They recently had two from local waters but they died within days of each other.  This specimen was caught in gill nets set for fish.
Report by Richard Lord (Guernsey)
Triton Whelk from Cornwall
Another one from Cornwall

31 January 1998:
Jon Makeham discovered the unusual gastropod mollusc Lameillaria latens under a rock at low water on Hannafore Beach, Looe. These gastropods were covered by a mantle that felt leathery. Two specimens were discovered, one was brown, the other a carmine red. The species was identified by the internal shell.

Subclass Opisthobranchia (Sea Slugs)
Gastropods that have lost their protective hard shell during the evolution of the species.

Akera bullata
Video footage by Penny Martin (Orkneys)

This interesting study shows the Sea Hare (=Akeroidea), an opisthobranch gastropodmollusc, swimming rather awkwardly with their heavy (shelled) end hanging down, rather like a large heavy beetle flying. 

Nudibranchs (BMLSS Records)
Tylodina perversa
This sea slug featured as a discovery news item.

Berthella plumula

Grey Sea Slug, Aeolidia papillosa  (photograph)

Sea Hare (Photograph by Steve Potter)

Sea Hare, Aplysia fasciata

Aplysia, the size if which (between 30 & 35 cm) indicates that it is Aplysia fasciata. It was photographed swimming in Helford River, Cornwall. It was seen on 25 August 2007 by Steve Potter

Aplysia fasciata is the largest and the rarest of the three species of sea hare found in the British Isles. It is an Atlantic species, found from the Channel to Angola (South west Africa and to Brazil) and also throughout the Mediterranean. It appears to reach its northern limit in Ireland and along the Channel coast of England. 
It is one of the largest sea slugs in the world. The other two British species are the relatively common Aplysia punctata variable in colour and growing to 20 cm; and the uncommon Aplysia depilans with different shaped back lobes, brown or green and growing to a maximum of 30 cm.

Sea Hare, Aplysia depilans, News Report
Sea Hare, Aplysia punctata (photograph of juvenile)
Sea Hares, Aplysia punctata. Autumn report from Cornwall
Sea Hares, Aplysia punctata. May report from Cornwall

Bernard Picton's Nudibranch Site

Best Nudibranch Links

Sacoglossan Sea Slug     Elysia viridis

Photograph by Andy Horton
Specimen from Old Fort (Photograph by Andy Horton)This small sea slug occurs on the shore in the south and west of the British Isles. On juveniles the green or blue spots may be absent. It is reported to feed on the seaweed Codium, but it has been discovered where this weed is absent.

It has been recorded from the Old Fort (opposite Kingston Beach on the other side of the Adur estuary), Shoreham-by-Sea, Sussex, where the only weed immediately noticeable is Fucus serratus. If you search you will probably find Ulva and Enteromorpha, and I have discovered Cladophora growing on the Fucus.

I have also discovered this sea slug in whelk egg cases.                   Andy Horton

Subclass Pulmonata (Terrestrial and freshwater Snails)  lunged snails.

Class Bivalvia   (=Pelecypoda)
Amande Glycymeris glycymeris
Lamellibranchia or Bivalvia (Mussels, Cockles, Venerids, Piddocks, Scallops, Oysters etc.)

Bivalve Molluscs of Norway (Thumbnails by UW Photo)
Molluscs on the Lulworth Bank, Dorset Coast, English Channel
Oyster & the Slipper Limpet
Razorfish (News Item)
Teredo (Shipworm)

December 2012

Gaping File Shell
Photograph by Darryl Mayer (Dive Tramp)
Darry Mayer Photograph Gallery
Fife Powerboat Training Centre

A massive colony of the Gaping File Shell, Limaria hians, has been discovered in Loch Alsh, a sea inlet between the Isle of Skye and the western Scottish mainland. The reef habitat covers an astonishing  4.6 sq miles (7.5 sq km) and was discovered during a survey commissioned by Marine Scotland. It is the largest known colony of Gaping File Shells in seas around the British Isles and possibly the world. Numbers of the bivalve mollusc exceed 100 million and they create their own specialised habitat with unique fauna.

Guardian News Report

12 May 2009
A large native European Oyster, Ostrea edulis, weighing 1.36 kg,  width 180 mm, length 170 mm and depth 70 mm  was spotted on Plymouth fish market in a box of mixed fish bought by merchant, Peter Randall of Mevagissey, and is now in the Mevagissey Aquarium

Report by Doug Herdson (Fish Information Services)
on the Marine Wildlife of the NE Atlantic Ocean (Yahoo Group)

BMLSS Oyster & Slipper Limpet

28 October 2007
A Quahog Clam, Arctica islandica, dredged up off the coast of Iceland was thought to be between 405 and 410 years old and the oldest animal alive on Earth until it was killed. Researchers from Bangor University in north Wales said they calculated its age by counting rings on its shell. 

Bangor University Report

6 January 2005
A walk along the Sandwich Bay seafront revealed the first 2005 record of the pretty bivalve mollusc Moerella donacina, (pic) a type of tellin which was only discovered to be present at Sandwich in 2004.
Sandwich Bay (non-avian) Nature 2005

BMLSS Turtles

17 January 2004 
The pretty bivalve mollusc Moerella donacina (pic) was collected by the Kent Shoresearch group at Sandwich Bay. This is the first known record of the mollusc from this area. The record was submitted by F. Booth.
Kent & Medway Biological Records Centre Monthly Records 2004

Class Cephalopoda

Octopuses, Cuttlefishes, Squids etc.
Click on the image for a link to the Cuttlefish and Cuttlebones web page

Cuttlefish Sepia officinalis

BMLSS Octopus
Identification guide for shelf cephalopods in the UK waters (North Sea, the English Channel, Celtic and Irish Seas)

Message: 10
   Date: Mon, 16 Oct 2000 11:12:32 +0100
   From: "Stella Turk" <>
Subject: Spirula on the strandline

More beachcombing!

Yesterday Richard Driver (with Paul Gainey) found, amongst other items, the coiled shell of Spirula spirula.  This tiny cephalopod (more closely related to the cuttlefish than the octopus) is believed to live in the depths of the Sargasso sea.  Shells are occasionally cast up on the western coasts of Britain and various countries of mainland Europe, but never - so far - with the remains of the living animal. This one was found on Perranporth Beach, Cornwall, and was exceptionally large at 25 mm (one inch), as they are rarely more than half an inch. I must do some surfing to find out what the latest research has to offer about this small mollusc.

Stella Turk
Report on Vince Smith's One-List/Cornish Wildlife

Architeuthis: the Giant Squid
BMLSS Octopus
Cephalopod Page (NHM Host)
Cephalopod pages at the National Museum of Natural History, Washington DC
Colours of Shells, Why?
Conchological Society
Conchological Society EForum
Cuttlefish Page
Cuttlefish Pages (Matt Stribley)
Cuttlefish Report 2000 (Cornwall)
Common Octopus News Report
Curled Octopus
Seashells of Eigg
Sepiola (Little Cuttle)
Shellfish Poisoning (Harmful Algae Page)
Shell Pigments (Ref.)
Squids & Squid Eggs masses

Link to the Conchological Society web pages

 All About Seashells
 Checklist of European Marine Mollusca
 Conchological Society
 Conchological Society EForum
 DOMMIC (Distribution of Marine Molluscs in the Channel)
 European Seashells & Diving
 General Guides (useful for molluscs)
 Italiana di Malacologia
 Marine Mollusca Bibliography
 Marine Molluscs Photographic Gallery
 (Marine Wildlife of the North-east Atlantic Ocean Group)
 Mollusc Identification Books
 Mollusca eList
 Seashells of Eigg
 Seashells on the Seashore  (a collection)
 Strandline Quiz
 Zoological Record (BIOSIS):   Mollusca


21 July 1999
A new licensing scheme is being proposed by the Government to protect crustaceans and other shellfish from being over-exploited. Fisheries Minister Elliot Morley said that there has been "increasing concern about the rate of exploitation of shellfish stocks in UK waters. The current state of shellfish stocks requires us to make progress in conserving this vulnerable resource. The new scheme is likely to reduce the number of boats fishing for shellfish to around 3,000...."
The value of the shellfish industry in the UK is now £165 million, or one third of all UK fish landings.


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