Atlantic jackknife clam

Atlantic jackknife clam
Empty shell of Ensis directus
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Order:	Veneroida
Family:	Pharidae
Genus:	Ensis
Species:	E. directus
Binomial name
Ensis directus Conrad, 1843

Jackknife clam, cooked, valves open

The Atlantic jackknife , Ensis directus, also known as the bamboo clam, American jackknife clam or razor clam (but note that "razor clam" sometimes refers to different species), is a large species of edible marine bivalve mollusc, found on the North American Atlantic coast, from Canada to South Carolina as well as in Europe.

This clam lives in sand and mud and is found in intertidal or subtidal zones in bays and estuaries. Because of its streamlined shell and strong foot, it can burrow in wet sand very quickly, and is also able to swim. It gets its name from the rim of the shell being extremely sharp (stepping on one causes extreme pain and a trip to the doctor) and the shape of the clam overall baring a strong resemblance to an old fashioned straight razor.

At low tide the position of the Atlantic jackknife clam is revealed by a keyhole-shaped opening in the sand; when the clam is disturbed, a small jet of water squirts from this opening as the clam starts to dig. This species' remarkable speed in digging can easily outstrip a human digger, making the clam difficult to catch. Thus the species is not often commercially fished, even though it is widely regarded as a delicacy. The easiest way to catch jackknives is to pour salt on the characteristic breathing holes. The clam will try to escape the salt by coming up out of its hole, at which point you can gently grab the shell and pull it out of the ground.

Predators of Ensis directus other than humans include birds, such as the ring-billed gull (Larus delawarensis) in North America and the Eurasian oystercatcher (Haematopus ostralegus) in Europe, and the nemertean worm Cerebratulus lacteus[1].

The Atlantic jackknife clam is now also found in northwestern Europe, where it is regarded as a harmful exotic species. It was first recorded in Europe in 1978/79, in the Elbe estuary.

See also

• Jackknife clam

References

• The Long Island Shell Club, 1988. The Seashells of Long Island, the Long Island Shell Club Inc, New York State

External links

• Kenchington, E., R. Duggan and T. Riddell. 1998. Early life history characteristics of the razor clam (Ensis directus) and the moonsnails (Euspira spp.) with applications to fisheries and aquaculture Can. Tech. Rep. Fish. Aquat. Sci. 2223: vii + 32 p. [2]
• Camponelli, K. 2001. "Ensis directus" (On-line), Animal Diversity Web. Accessed August 27, 2006 [3].
• Gollasch Consulting. Exotics Across the Ocean - EU Concerted Action. Ensis directus