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  • José H. Leal

The Northern Quahog

The Northern Quahog, Mercenaria mercenaria (Linnaeus, 1758), measures up to 120 mm (about five inches). Its shell is trigonal to rounded, with commarginal ("concentric") ridges on the outer surface. It differs from its closest relative (and local native species), the Southern Quahog, Mercenaria campechiensis, by smaller maximum size, lack of commarginal ridges on central part of the external shell surface, and, most of all, by the violet-color tinges on the internal surface of its valves (absent in the Southern Quahog). Originally from the Eastern Seaboard of the US, the Northern Quahog has been introduced to the bays and protected waters of Southwest Florida originally via scientific experiments and the seafood aquaculture industry: the species was chosen over the native Southern Quahog because of the very short shelf life in this latter species. Both species can be found in the local areas invaded by the Northern Quahog, and hybrids are not uncommon.

The Northern Quahog, Mercenaria mercenaria, from the area between the Sanibel Causeway and Bunche Beach. Collected and photographed by José H. Leal.

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