Spiriferidae Brachiopod Shell Structures Inducive for Filter Feeding

The fossil shows distinct pyritization in addition to the calcite preservation. The family Spiriferidae is known for its prominent ridges with the middle recession called the sulcus that divides the symmetrical sides of the shell.

Paraspirifer bownockeri brachiopod fossil (52mm), Paulding, Ohio, Silica Formation, Middle Devonian (393 to 383 million years ago)

Paraspirifer bownockeri Features and Habitat:

Paraspirifer bownockeri is a large species of brachiopod that lived during the Middle Devonian time period in a warm shallow seabed that displayed extraordinary biodiversity in the fauna found in the Silica Formation. Trilobites (Eldredgeops sp. among the most prominent), Brachiopods, Bryozoans, Horn Corals, and others made up most of the early reef bed. Brachiopods are another example of living fossils with nearly 300-400 living species that live in the depths of todays ocean’s. Unlike most other examples of living fossils, brachiopods have remained physiologically unchanged. The fossil displayed above represents the Spiriferidae family of brachiopods which were studied for the distinct, large sulcus (recession within one halve of the shell) and large fold (protusion on the other halve of the shell).

Summary of Study Done into the Shell Morphology that induced Filter Feeding:

In a fluid dynamics simulation in which Shiino, Kuwazaru, and Yoshikawa scanned a well preserved specimen of Paraspirifer bownockeri, the researchers put the model into several different flow-current simulations to see how the design of the shell’s sulcus and fold would react to different flow conditions (Shiino et al.). The conclusion was that the shell’s sulcus would create a high pressurized region of water flow in which the animal would be able to draw in the nutrient-rich water of its surroundings to feed (Shiino et. al.). Likely instead of any muscle movement, the shell’s construction itself helped passively draw in nutrients.

Works Cited:

Shiino Y, Kuwazuru O, Yoshikawa N. Computational fluid dynamics simulations on a Devonian spiriferid Paraspirifer bownockeri (Brachiopoda): generating mechanism of passive feeding flows. J Theor Biol. 2009 Jul 7;259(1):132-41. doi: 10.1016/j.jtbi.2009.02.018. Epub 2009 Mar 6. PMID: 19269296.