Atlantic jackknife clam
|Atlantic jackknife clam|
|Empty shell of Ensis directus|
The Atlantic jackknife clam, 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. It has also been introduced to 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 can cause injury) and the shape of the clam overall bearing 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: in coastal Massachusetts, they are sought after in the summer by locals to make home cooked clam strips and most towns insist upon regulations dictating how many can be taken at a time. 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.
The Atlantic jackknife clam has inspired a kind of biomimetic anchor in development by a team at the Massachusetts Institute of Technology, adapting the clam's digging method for use in keeping undersea cables and potentially watercraft anchored securely.
This clam is also found in the Pacific Ocean.
- "Town of Ipswich Massachusetts : Shellfish Rules & Regulations". Town.ipswich.ma.us. Retrieved 2014-02-24.
- "Predation of the Razor Clam Ensis directus by the Nemertean Worm Cerebratulus lacteus". JSTOR 1350520.
- Morgan, James. "'RoboClam' could anchor submarines". BBC News. Retrieved 17 April 2014.
- The Long Island Shell Club, 1988. The Seashells of Long Island, the Long Island Shell Club Inc, New York State
|Wikimedia Commons has media related to Ensis directus (Atlantic jackknife clam).|
- Animal Diversity Web: "Ensis directus" — Camponelli, K. 2001 . accessed August 27, 2006
- Early life history characteristics of the razor clam (Ensis directus) and the moonsnails (Euspira spp.) with applications to fisheries and aquaculture — Kenchington, E., R. Duggan and T. Riddell. 1998. Can. Tech. Rep. Fish. Aquat. Sci. 2223: vii + 32 pgs.
- Gollasch Consulting. Exotics Across the Ocean - EU Concerted Action. Ensis directus