What is "jackknife clam"

n. marine clam having a long narrow curved thin shell [syn: razor clam, knife-handle]

Jackknife clam is a common name which is used for several species in the genera Ensis and Solen within the family Solenidae, species which are found on Atlantic and Pacific beaches of temperate North America. Species in these families are also found elsewhere in the world, but in other English-speaking countries they usually have other common names. All the species in these genera have thin, highly elongate shells. Many of these bivalves are collected for food.

Species include:

• Ensis directus
• Ensis minor - Ensis minor can grow up to 17 cm. in length. It is white, sometimes with reddish-brown markings.
• Ensis myrae
• Solen viridis
• Solen sicarius