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This shell is not your ordinary turkey wing

By Staff | Jun 4, 2009

Certain species of shells have such unique features that identification loses all of its challenge. The rectangular wing shape of the turkey wing (Arca zebra) definitely falls into this category. The striking brown zebra stripes contrasted against a creamy white background erase any feelings of indecision. The length of this rectangular shell is twice as long as the width. They can grow to a length of four inches. On live shell the color pattern is covered up by a dark brown periostracum that wears off as shell ages. This provides the perfect camouflage when the shell is amongst the sea grass.

Shallow-water rocky reefs from North Carolina to Brazil provide the perfect home for this species. They frequently are found in the crevices of the rock. The turkey wing is one of the bivalves that hang onto rocks with an anchor called a byssus but instead of being a series of sticky threads like jingle shells are tethered by, the foot of the turkey wing secretes a soft leathery cord.

Sometimes this species is referred to as a Noah’s ark because of the shape displayed when the two valves are connected. It also is referred to as a zebra ark obviously related to the prominent stripes that may run the length of the shell.

The sculpture of the turkey wing is intriguing. It is a sturdy, thick shell with 20 to 30 radial ribs as well as very fine concentric threads that cross both the ribs and the spaces between the ribs. The hinge is straight and long. The umbones, or elevations on each side of the hinge are prominent and the anterior end of the shell slopes downward. If you are lucky enough to find a pair, you will notice that the long side of the opening doesn’t fit together very well. This is because there is a hole called the byssal notch through which the byssus is secreted by the foot.

The external ligament of a turkey wing is a dark chestnut-brown color. Arks don’t have siphons (flexible tubes that water is sucked in through) but they have a pair of gills. As the water passes over the gills, oxygen is extracted but the gills also trap small particles of food. For most bivalves this food is plankton which is free floating organisms. Although plankton moves, they can’t swim against currents but they can move vertically in the water column.

As a child I found the perfect use for ark shells. They were just the right size and shape for digging. After all, it wouldn’t be the perfect trip to the beach without a castle complete with a moat and a drawbridge. In some parts of the world arks are used for bait and in Bermuda the turkey wing is used to make seafood pies.

This week at the Museum:

Monday, June 8th Time: 2 p.m. Live Tank Demonstration Cost: Museum Entrance Fee

Tuesday, June 9th, 9:00 a.m. Free guided beach walk sponsored by The Shell Museum and J.N. Ding Darling Wildlife Refuge. Walk led by Dotty DeVasure and Pam Burt. Participants will meet at Gulfside Park, Algiers Road, Sanibel at 9:00 am. The walk will last about an hour. . Bug spray, water, hat, and sunscreen suggested. Sanibel Parking fee- $2/hour.

Tuesday, June 9th, 11:30 a.m. Workshop: How to Find, Clean, and Pack Shells For Safe Travel Cost: Museum entrance fee.

Wednesday, June 10th, 11:30 a.m. Workshop: How to Find, Clean, and Pack Shells For Safe Travel Cost: Museum entrance fee.

Friday, June 12th, 10 a.m.-11 a.m. Story Time At The Museum Ages: 3 & Up with parents. Cost: free Join us for a special story about the sea, tidal pools, what’s under the sea and much more. Story time will be followed by a visit to the Museum’s live tank to view the animals that make shells.