LAMARCK’S RAZOR CLAM/ SHELL Solen lamarckii Chenu, 1843

Dorsal and Ventral views of Lamarck’s Razor Shell Solen lamarckii

 

Razor shells are beautiful rectangular shaped clams that look similar to old straight razors. A straight razor has a slot for the blade and it can fold up after use into its handle. They are also referred as Open razors or Cut-throat razors. Though the first appearance of old straight razors have been reported from a Sheffield manufacturer in England (1680), beautifully decorated handles and cast steel blades were invented in 1740 by Benjamin Huntsman. In French it is called as Couteau de Lamarck.

The shell of Lamarck’s razor clam is elongated, equivalve with only one peg-like cardinal tooth (the central teeth of bivalve shell) in each valve with a long and narrow body. Shells can grow up to 10 cm (8 cm is common). Umbones (Umbo- A knoblike protuberance arising near the hinge of a bivalve shell) are not very prominent and the foot is cylindrical. Conspicuous concentric growth marks are seen often changing abruptly in direction along a diagonal line running from the umbones to the posteroventral end of valves. There is a prominent, glossy periostracum (The periostracum is a thin organic coating or “skin” which is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods) while the interior part of the shell is porcelaneous. Anterior adductor muscle scar (Adductor muscles leave noticeable scars or marks on the interior of the shell’s valves) is commonly larger than the posterior. Siphons (Siphons in molluscs are tube-like structures in which water flows) are naked and fused at the base.

Lamarck’s razor clams are filter feeding animals that are well adapted to swift and deep burrowing in soft bottoms with their powerful foot. The rectangular and cylindrical two-part shell that is narrow and thin, aids the clam to slip easily through the sand. Its foot has the capacity to swell at the end and protrude anterior through the narrowly elongate shell. They dwell in the intertidal areas, littoral and sublittoral to a depth of 25 m, where the substratum is smooth.

The identical shape and appearance of the Lamarck’s razor shell with an old straight razor

Lamarck’s razor clams are rarely seen as they usually bury in the sand. They can be sighted if undisturbed close to sea grass habitats with the siphon pointing outside the substrata (entire shell is buried inside). The long siphons are used for breathing and feeding. Through the siphon, the clam sucks in water current and the internal enlarged gills aid in sieving the food particles brought in along with the water current.

Though reports exist that Lamarck’s razor clams are artisanlly exploited and marketed in India, there are no concrete research findings to support this claim. In Sarawak (Malaysia), the razor clam fishery started to grow way back in the 1970’s and is a well established fishing sector now. The clams are also exploited in Sri Lanka and many of the south-east Asian countries. Razor clams are affected sometimes by Red tides and HABs (Harmful Algal Blooms). The affected clams are harmful to eat causing shell fish poisoning in humans.

 

Taxonomic status

Kingdom: Animalia

Phylum: Mollusca

Class: Bivalvia

Subclass: Heterodonta

Infraclass: Euheterodonta

Superfamily: Solenoidea

Family: Solenidae

Genus: Solen

Species: S. lamarckii

Author: Chenu, 1843

 

IUCN Status

Not Assessed (NA)

 

References

IMAGE source – Old Straight Razor – http://forums.roadbikereview.com/lounge/old-school-shave-246175-2.html

 

©Deepak Samuel March, 2014