Overview

Comprehensive Description

Description

 Pholas dactylus is a boring bivalve, approximately elliptical in outline with a beaked anterior end, up to 12 cm long. The shell is thin and brittle with a sculpture of concentric ridges and radiating lines. The shell is dull white or grey in colour, the periostracum yellowish and often discoloured. The siphons are joined and at least one to two times the length of the shell, white to light ivory in colour. Pholas dactylus has phosphorescent properties, the outlines of the animal glowing with a green-blue light in the dark.
  • The shell is often thicker in older individuals, up to 2 mm thick in 12 cm specimens (E. Pinn pers. comm.).
  •  
  • Although thin and brittle the shell of Pholas dactylus has a cross-lamellar design which efficiently deflects cracks away from the bulk of the shell which gives it the strength to burrow through soft rocks.
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©  The Marine Biological Association of the United Kingdom

Source: Marine Life Information Network

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Distribution

Range covers both subprovinces of Acadian and Virginian.
  • North-West Atlantic Ocean species (NWARMS)
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© WoRMS for SMEBD

Source: World Register of Marine Species

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Ecology

Habitat

Depth range based on 2 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 2.75 - 3.35

Graphical representation

Depth range (m): 2.75 - 3.35
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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 Pholas dactylus bores into a wide range of substrata including various soft rocks such as chalk and sandstone, clay, peat and very occasionally in waterlogged wood. Found from the lower shore to the shallow sublittoral.
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Source: Marine Life Information Network

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Associations

Plant / grows inside
animal of Pholas dactylus grows inside dead, submerged trunk of Trees

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Evolution and Systematics

Functional Adaptations

Functional adaptation

Shells grind through rock: piddock
 

The shell of the piddock grinds through rock using hard shell projections.

   
  "Some piddocks (e.g. Pholas dactylus) slowly bore themselves into solid rock. They use their foot as a lever by which they move their shells, which are provided with extremely hard surface projections, back and forth to scrape the rock and slowly hollow out a burrow." (Pallasmaa 1995:59)
  Learn more about this functional adaptation.
  • Pallasmaa, J. 1995. Animal architecture. Helsinki: Museum of Finnish Architecture. 126 p.
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© The Biomimicry Institute

Source: AskNature

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Molecular Biology and Genetics

Molecular Biology

Genomic DNA is available from 1 specimen with morphological vouchers housed at British Antarctic Survey
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© Ocean Genome Legacy

Source: Ocean Genome Resource

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Wikipedia

Pholas dactylus

Pholas dactylus is a luminescent clam-like species of marine mollusc found on the coasts of the North Atlantic and the Mediterranean Sea. It bores into gneiss. It was once a highly esteemed food in Europe.[2] [1]

Pholas dactylus: 1. Animal in the shell a) foot b) siphons c) inhalant orifice d) exhalant orifice. 2. shell e) accessory valves or plates

It is sensitive to light, retracting into its shell when exposed to it.[3]

Ancient history

Pliny spoke of luminescence in the mouths of people who ate Pholas, the rock-boring shell-fish, and of such importance is this phenomenon that it is even said to have gained the first king of Scotland his throne.[4]

References

  1. ^ a b Gofas, S. (2012). Pholas dactylus Linnaeus, 1758. Accessed through: World Register of Marine Species at on 2012-02-23
  2. ^ "Pholas dactylus (clam) - Britannica Online Encyclopedia". Britannica.com. Retrieved 2011-09-24. 
  3. ^ Selig Hecht (1927). "The kinetics of dark adapatation". The Journal of General Physiology 10 (5): 781–809. doi:10.1085/jgp.10.5.781. PMC 2140923. PMID 19872361. 
  4. ^ [1] Author: Field Naturalists' Club of Victoria, Volume: v.21, 1904-1905, Subject: Natural history; Natural history, Publisher: [Melbourne] Field Naturalists Club of Victoria, Year: 1884, Possible copyright status: NOT_IN_COPYRIGHT, page 93
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