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STARFISH EATING A CRINOID
Starfish: Onychaster flexilis
Crinoid: Actinocrinites gibsoni
Edwardsville Formation, Montgomery County, Indiana In this exhibit the ancient struggle of life and death is here preserved in the form of a Starfish feeding on the anal pouch of a crinoid. While Starfish are regularly found in association with Crinoids, scientists are not sure whether this was a symbiotic, i.e., mutually beneficial, relation or a predator-prey relation. As is illustrated by the detail image below, amputated members of the calyx can be seen where the Starfish would have gained his now-permanent position. In other words, this fossil could be the "smoking gun" that seems to show conclusively that the relation between these creatures was indeed predatory. This would also explain the relative dearth of Crinoids today. Cactocrinus sp. Edwardsville Formation, Crawfordsville, Indiana Histocrinites sp. Edwardsville Formation, Crawfordsville, Indiana Onychocrinus ulrichi Edwardsville Formation, Crawfordsville, Indiana Crinoids Edwardsville Formation, Crawfordsville, Indiana Ascetocrinus rusticellus Edwardsville Formation, Crawfordsville, Indiana
Mississippian, about 380 million years old.
Matrix is about 130 mm (5 inches) across. 
Mississippian, about 310 million years old.
Matrix is about 52 mm (2.5 inches) long.
Mississippian, about 310 million years old.
Matrix is about 230 mm (9 inches) long.
Mississippian, about 310 million years old.
Matrix is about 100 mm (4 inches) across.
Mississippian, about 310 million years old.
Matrix is about 100 mm (4 inches) across.
Mississippian, about 310 million years old.
Matrix is about 100 mm (4 inches) across.
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