Barbatia cancellaria (Lamarck, 1819)
Family Arcidae (Ark Clams)
The Red-brown Ark attaches to hard surfaces in shallow water, such as at the base of sea fans or under rocks, using a strong byssus produced by the foot. This is one of the most common species in the Florida Keys, and ranges from North Carolina to Brazil. Its hairy periostracum (the outer organic layer on the shell) is thick and fibrous, with extensions that often project beyond the shell margins. Ark Clams are well-known for their taxodont dentition — many small hinge teeth along a linear hinge plate along one inner edge of the shell — firmly aligning the shells together when they close. Hemoglobin is present in their blood in red blood cells unknown elsewhere in Mollusca. Arks are identifiable in the fossil record back to the Jurassic Period (200-150 million years ago). Some species are raised in aquaculture for human consumption in Asia .
Evolution on the Half Shell...
The Assembling the Tree of Life: Bivalvia project (BivAToL) is a part of the Assembling the Tree of Life initiative, a large research effort sponsored by the National Science Foundation. Its goal is to reconstruct the evolutionary origins of all living things.
Jetsam & Flotsam
Some of the BivATOL team met in early May at the Mote Marine Laboratory’s Tropical Research Station at Summerland Key, FL for a combined collecting trip and coding workshop. Both activities are essential to our project’s goal of determining the phylogenetic relationships among the bivalve families.
After collection, many of the species’ visible and molecular characteristics must be compared and “coded,” after which the phylogenetic computer analyses will be run to produce the final “tree” from which a hypothesis of relationships can be made. Below is an example of a portion of such a phylogenetic tree. Families that are on nearby branches are more closely related to each other than those further away.