Fragile Surf Clam
Mactrotoma fragilis (Gmelin, 1791)
Family Mactridae (Surf or Trough Clams)
Bivalve siphons come in many shapes and sizes. Mactrid siphons are fused almost to the tip and are sometimes sheathed with periostracum (the outer organic layer of the shell), the yellow flaky material on the posterior (at right) slope of this juvenile from the Florida Keys. Mactrotoma fragilis ranges from North Carolina, through the Caribbean and Central America, and to Uruguay in South America. It’s larger cousin the Surf Clam (Spisula solidissima) supports a commercial fishery in North America (think fried clam strips!!). The shells of some larger species were used historically as food and scraping tools by native peoples in North America and Australia.
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.