Vulsella vulsella (Linnaeus, 1758)
Family Malleidae (Hammer Oysters and Sponge Fingers)
The bivalve known as “Sponge Fingers” is a type of oyster that lives embedded in large sponges. Other members of this family settle on coral reefs, nestling in crevices, and, as they grow, become effectively embedded in the algae and rock that form the surface of the reef. Only the free edges of the bivalve remain exposed, like protruding fingers, to allow water to enter for feeding and respiration. Because the sponge is a living, growing animal too, Sponge Fingers need to grow in pace with the sponge to maintain water contact. Because of their embedded habitat, these bivalves are irregular in shape and thin-shelled. The foot of a malleid is divided into two parts: a small portion that produces the byssus threads, and a longer “accessory foot” that is used for cleaning debris from the mantle cavity. These individuals were collected for the BivAToL project by Gonzalo Giribet, during a scuba dive off Amity Point, North Stradbroke Island, Queensland, Australia, at 12 m depth.
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.