|The teeth of Ensis arcuatus|
Ensis is a taxonomic genus of clams, best known for their unusual elongated body shape causing species in this genus to be commonly known as razor clams or jackknife clams. They are specialized for digging rapidly, which helps them to escape from predators. They also have a very high reproduction rate, causing them to become a dominant species on many beaches. Ensis is also well known as a good source for food.
Ensis is a genus of specially shaped mollusca. Ensis species look like curved sticks, being mostly colored brown and white in layers. They grow to be 15 inches long (40 cm) at the most, and at least 1 inch long for the smallest. Their shells are smooth. They use feet to move around. Also they are specialized to dig into the sand to the point that they can dig faster than a man can dig. 
Ensis has separate sexes. The perfect temperature for mating is 55F, so normally they mate in spring and autumn. Males release the sperm into water. Later on, the sperm flow into the female's gill. After fertilization, the female releases one-thousand to 100 million eggs at a time.
There are two stages of development after the fertilization. The first stage is the trocophore. These are small, free swimming, larvae. They look like pears that are translucent and have cilia. The second stage is called the plankton stage which is also a free swimming stage. Free swimming allows the larvae to spread out through the ocean. After a time of swimming, they settle down in safe places and become adults. As soon as they become adult, they only move up and down in the sand, not side to side.
Ensis species are filter feeders, which filter plankton from the water and consume it. Ensis species are found throughout the world, and mostly live on beaches. At high tide the Ensis come out from the sand and filter feed, but at low tide the clams burrow into sand for safety.
Ensis species can live up to 18 years, but on average they live about 5 years. When they bury themselves in the sand, they can rapidly move the sand with their feet. It only takes 15 seconds for them to bury themselves, but they can dig up to 20 meters. In areas where these species are common, the burrows that they make affect the character of the sand that they live in.
For humans, Ensis species can be sources of food. These clams can be caught, sold, and eaten during July to September. 
Ensis species are also great sources for food. Not only the taste, but their long shape and good smell attracts customers. Ensis species are easy to harvest.
Mostly they are harvested in Alaska, In Alaska they harvest 600,000 pounds annually in just at Cordova area. They have been harvested from 1916 and the area is still active. Ensis species can also be found in Belgium, Netherlands, Germany, Britain and Denmark. They are also popular at east Pacific Ocean areas, such as Korea, Japan and China.
Rarely they contain roundworms, which are parasitic creatures that can live in Ensis species. If the clams are washed before cooking, they will easily fall out from Ensis. Even though they are still inside of Ensis, they have no harm for humans if well cooked.
-  Dave nelson, 1994.
-  unknown, 6 August 2006.
-  Camponelli, K, December 10, 2010
-  NOAA, July 16, 2004
-  Alaska Department of Fish and Game, 2010
-  Unknown
-  StasoSphere
Oct 22 2010