Cross barred venus

Taxobox
name = Cross barred venus

---

regnum = Animalia
phylum = Mollusca
classis = Bivalvia
ordo = Veneroida
familia = Veneridae
genus = "Chione"
species = "C. cancellata"
binomial = "Chione cancellata"
binomial_authority = Linnaeus, 1767

The cross barred venus, "Chione cancellata", is a medium-sized saltwater clam, a marine bivalve mollusc in the family Veneridae.

It grows to be 1 3/4 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 coloration varies, but in the northern part of its range, it usually has a grayish yellow-white exterior, occasionally with a few lavender radial stripes. The shell interior is usually purple.

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. Its habitat was, until recently, thought to range from New Jersey to Brazil. Although it is sweeter in taste than the northern quahog, "Mercenaria mercenaria", it is much 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.

ee also

* Veneridae

References

* [http://mollus.oxfordjournals.org/cgi/content/short/66/4/517 Phylogenetic Analysis of Chione]
* [http://www.edwardtbabinski.us/beach_kids/sea_shells/cross_barred_venus/ Cross Barred Venus Clam] and [http://www.ncseagrant.org/ NC Sea Grant]

External links

* [http://www.blackwell-synergy.com/doi/abs/10.1111/j.1744-7410.2006.00036.x Embryonic development and shell differentiation in Chione cancellata]