Produced by the Population Genetics and Evolution class, Furman University

The Ordovician: Brachiopods
Brachiopods (also known as lamp shells) were the first bilaterian animals to lose their adult mobility and encase themselves in an external shell. They became sessile, benthic suspension-feeders, and they are among the most abundant fossils in the geologic record (Kazlev 2002). The shell is made up of two parts (bivalved) and composed of calcium carbonate or calcium phosphate and chitinous organic substance. Although similar in appearance to clams, they belong to the group Lophophorata, related to Bryozoa and Phoronida. They use a fringe of tentacles, known as the lophophore, for feeding and respiration. Unlike mollusks their shell is unequal, with one side possessing the attachment for the pedicle, a muscular stalk, which attaches the organism to the substrate. In the past, brachiopods have been split into two groups, Articulata (with an articulating hinge) and Inarticulata (without), however it is now believed that these are unreliable classifications. It has been suggested that brachiopods may be polyphyletic, evolving from separate phoronid-like ancestors. Brachiopods still exist today, although in much less abundance, with only 300 to 500 species surviving from the 15,000 known species.

Page by Megan Aprill
Living brachipods. Photo from: www.palaeos.com

Waggoner B. 1995. Introduction to the Brachiopoda. University of California Museum of Paleontology (UCMP). Accessed Feb 6 2010.

Kazlev MA. 2002. Metazoa: Lophotrochozoa: Brachipoda. www.palaeos.com. Accessed Feb 6, 2010

Brosius L. 2008. Fossil Brachiopods. GeoKansas. Accessed Feb 6, 2010.