Biodiversity & Conservation

White piddock - Barnea candida

Barnea candida

Image National Museum Wales - Barnea candida in situ. Image width ca XX cm.
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Distribution map

Barnea candida recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Why do the maps differ?

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Barnea candida is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Mollusca Snails, slugs, mussels, cockles, clams & squid
Class Bivalvia Clams, cockles, mussels, oysters, and scallops
Authority (Linnaeus, 1758)
Recent synonyms None
Map icon Recorded Distribution in Britain and Ireland Occurs around the southern half of Britain but almost entirely absent from the north of Britain and the coast of Ireland.
Habitat information icon Habitat information Burrows into wood, peat and soft rocks on the lower shore and sublittoral.
Text page icon Description Barnea candida has a white shell with a yellowish or light brown periostracum, and has pronounced sculpturing anteriorly composed of concentric ridges crossed by ribs with spines. The shell is fragile, narrowly elongate and oval, up to 6.5 cm in length. Barnea candida have large foot muscles and visceral mass, and are unable to retract completely within their shells. The anterior and posterior margins are rounded. The hinge line has a slender projection (apophysis) just below the beak of each valve which serves as the attachment area for the large foot muscles. The umbones are positioned in the anterior third of the shell with an accessory plate, the protoplax, placed dorsally in front of them. The margin is crenulate with spines about the posterior pedal gape, smooth elsewhere. The siphons of Barnea candida are of equal length and united. These can reach 4 to 5 times the length of the shell. The inhalent siphon has 10 to 12 large, and several small, hairs surrounding its opening whilst the exhalent siphon has none. Both siphons are pale brown in colour and minutely papillose, and are tipped with a narrow band of red brown.
Identifying features
  • Fragile, date-shaped shell up to 6.5 cm in length.
  • A single dorsal plate, the protoplax, lies in front of the umbones.
  • Anterior and posterior margins rounded.
  • Posterior margin gapes.
  • Radiating ribs bear spines anteriorly.
  • A slender calcareous projection (apophysis) below both beaks.
  • The siphons are united and may extend 4 to 5 times the length of the shell.
Additional information icon Additional information No text entered

This review can be cited as follows:

Susie Ballerstedt 2006. Barnea candida. White piddock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 28/11/2015]. Available from: <>