Scintillona cryptozoica (Hedley, 1917)
Family Galeommatidae (Galeommatid Clams)
This half-inch-long bivalve from Australian mudflats crawls like a snail and is covered with frilly tentacles, several of which are longer and red-tipped. Although this species is free-living, many species of the family Galeommatidae live in commensal relatiionships with other invertebrates, especially crustaceans (crabs, mantis shrimps, etc.) and echinoderms (sea urchins, sea stars, etc.). They are fragile bivalves, with thin, internal shells covered by mantle tissue bearing sensory tentacles. They protect themselves in other ways, usually by occupying a protective habitat such as on the body or in the burrow of another animal. The foot is modified for crawling, and produces byssal threads (like those of mussels, but unusual for most species of bivalves as adults) that secure it to its substrate or its host.
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.