Cross-barred Venus, or, "Florida Cross Bar Venus"
Chione cancellata (Linnaeus 1767)
Family Veneridae
The Cross-Barred Venus is a bi-valve with a medium thick shell which grows to about 2" and is recognized by cross bar extending from its umbones. It's standard color is off white (gray). Some have brown color patterns that along the vertical lines as the shell below:
Cross barred Venus with broken brown bands (S. Hutchinson Island 2020)
The variety of color is displayed in the group of Cross-Barreed Venus below, the topmost shell is the standard color:
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Cross-Barred Venus:
Unusual Lines and Coloration
By Patricia B. Mitchell.
A sturdy and distinctive little clam shell, the Cross-Barred Venus is marked by radiating and concentric lines, giving it a miniature lattice-work appearance. The slightly inflated shell is whitish often with often brown markings. On the inside of the shell there is a central white area where the mantle of the mollusk was attached, and on each side of the mantle area there are two somewhat round areas to which were attached the adductor muscles. Offtimes the inner surface of the shell also displays a pretty purple color. On the hinge of the shell there are two “teeth.” The outer edge of the shell is finely ridged.
The clam feeds by filtering plankton from the seawater, using a siphon system to draw water over a mucus collecting net.
The preferred habitat of the Cross-Barred Venus is in the sand of eelgrass beds.
Incidentally, living Cross-Barred Venus clams are good human food. Collect enough of them, and you can make a tasty chowder. (The clams are seldom as large as 2 inches across.)
The beachcomber or shell collector will enjoy finding the shell halves washed ashore anywhere from North Carolina to the West Indies.
An alternate name for the attractive mollusk is the Dog Clam; why, I do not know.
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Chione cancellata
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Chione cancellata
Chione cancellata (Linnaeus, 1767) 2013 000.JPG
Scientific classification edit
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Heterodonta
Order: Venerida
Superfamily: Veneroidea
Family: Veneridae
Genus: Chione
Species: C. cancellata
Binomial name
Chione cancellata
Linnaeus, 1767
Chione cancellata, is a species of medium-sized saltwater clam, a marine bivalve mollusc in the family Veneridae, the venus clams.
The species is now understood to be strictly Caribbean in distribution. The more northern species which resembles this, which is usually called the "cross-barred venus" and which was considered to be C. cancellata for many years, is now known to be Chione elevata.
Contents
Shell description
This species grows to be 13⁄4 inches across, and has a rounded, triangular shell with both strong concentric ridges and strong radial ribbing, which together form a raised crisscross pattern of ridges, hence the specific name, cancellata or cancellate.
The interior of the shell possesses crenulations on its bottom edge, and like most Veneridae it has well-developed lateral and cardinal teeth on the hinge line.
The shell of C. cancellata sensu stricto is quite brightly colored and patterned. (This is in contrast to the species C. elevata which usually has a grayish yellow-white exterior, occasionally with a few lavender radial stripes. The shell interior of C. elevata is usually purple.)
Habitat
The species commonly lives on sandy bottoms of sounds and shallow offshore waters, and the shells are commonly found washed ashore on sound and ocean beaches.
Distribution
This species was, until recently, thought to range from New Jersey to Brazil. It is now known that the Caribbean Chione is in fact C. cancellata and the more northern clam is a different species, C. elevata.
Human use
Although this clam is sweeter in taste than the northern quahog, Mercenaria mercenaria, it is a lot smaller, and is rarely eaten.
Genetic evolution and anatomy
The taxonomic status of the common tropical western Atlantic venerid bivalve, Chione cancellata, was radically revised in 2000. What had previously been thought to be one species was discovered to be a "cryptic species pair" and as such it was divided into two separate species, on the basis of morphological, morphometric and phylogenetic analyses.
The more colorful Caribbean species is still called C. cancellata. However, specimens inhabiting waters off the United States and Central America south to Belize, are in fact a different species. This species was described originally by Thomas Say as Chione elevata. Examination of specimens of both species supported the separation, including difference in shell sculpture, hinge morphology, and size of the pallial cavity.
A phylogenetic analysis of extant species failed to define the exact evolutionary history of C. cancellata and C. elevata. Separation of the two species suggests an ancient faunal division in the western Atlantic between the northern Caloosahatchian Province and the southern Atlantic Gatunian Province. This hypothetical division has been dated back to the Early Pliocene.
See also
Veneridae
References
Phylogenetic Analysis of Chione
Cross Barred Venus Clam and NC Sea Grant
External links
Embryonic development and shell differentiation in Chione cancellata