 |
Bivalve of the Day |
 |
Smith’s Tiny Condyl Clam
Carditopsis smithii (Dall, 1896)
Family Condylocardiidae (Condyl Clams)
The prodissoconch or larval shell (artificially colored green in this scanning electron micrograph) of diminutive Carditopsis smithi is relatively large and bordered by a strong ridge. Very little is understood about the anatomy of condylocardiids. The family is very young paleontologically, known only since the Tertiary, and is represented by at least 21 living genera and at least 65 species, distributed worldwide but mainly in the antiboreal regions. Some features of condylocardiids (such as an adult byssus, brooding larvae, absence of the outer demibranch of the gill) suggest that their evolution involves pedomorphosis, or the retention of larval characters in the reproductive adult.
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.
Here, Mya is more closely related to Dreissena (zebra mussels) than to Teredo (shipworm clams).
 |
 |
