Cockles and Angelwings

Cockles

Cockles along the beach

Special to The Star
Published: Tuesday, December 24, 2013 at 09:59 AM.

By Tom Baird

 

Ever notice how the beach changes from summer to winter? We are now in the “winter beach” and this is the time when shelling is best.

Throughout the summer, sand is deposited on the beaches and the dunes build. The beach becomes higher and wider. In winter, changes in wave height and direction cause sand to be pulled offshore from the beach and deposited in protective offshore sandbars. The winter beach is narrower and lower. While this phenomenon is more extreme on the Atlantic and Pacific coasts, nevertheless our Panhandle beaches also go through this cycle.

Because sand is pulled off the beach in winter, shells that were buried all year are now exposed. Both tourists and residents can be seen carrying buckets or bags of shells to take home. The most commonly collected shells are the giant cockles and white angelwings, with the occasional empty shell of a large left-handed whelk.

The giant cockle or heart cockle (Dinocardium robustum) is familiar to most residents. It is that big – up to five inches long - tan or cream colored bivalve with parallel ribs with brown patches. It occurs around Florida wherever one finds their preferred habitat - sandy shallows off beaches. Therefore, the big bend area, with its lack of wave energy, and therefore lack of beaches, does not offer suitable habitat for the giant cockle. The giant cockles found on our Gulf beaches is a more colorful variety than their Atlantic cousin and is classified as a subspecies, Dinocardium robustum vanhyningi, often called Van Hyning’s cockle.

These bivalves are filter feeders that use their long muscular foot to dig down into the sand and extend their siphons into the water column to pump in suspended food particles. The cardium part of theirgenus name, Dinocardium, may remind you of heart. To see why they are sometimes called heart cockles, find two shells of about equal size and place their edges together. Now turn them to the side and look at the shells with their edge facing you. The profile from the side resembles a Valentine heart. The fully grown shells are also about the size of a human heart.



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