THE LAST MEAL OF A MISSISSIPPIAN STARFISH

There is little information on food selection and feeding behavior of fossil asteroids. There is even less written about the prey species involved in predator-prey studies. The only studies found were starfish-clam, starfish-snail, somasteroid-detritus and starfish-sponge. This starfish-sponge relationship is the basis of this study.

A new genus and species of Mississippian starfish was recently reported from mid-Missouri. Identical monaxon sponge spicules were present within the body cavity and on the oral surface. The spicules were identified as Belemnospongia fascicularis Ulrich, 1890, a common sponge in the Mississippian of the Midwest. No whole specimens of sponges were found, but many examples of concentrated globs of spicules indicated entire organisms. Spicules were also found widely scattered, as well as in localized pockets of several thousand each. There is little doubt that this sponge was abundant at the site and could have been fed upon with regularity.

Feeding behavior of living asteroids is well documented. One method involves swallowing the prey whole, as was found in this starfish-sponge relationship. Today, food selection by asteroids indicates they feed on a variety of organisms, including sponges. Inspite of sponges having the unappetizing qualities of disagreeable taste, odor and spiculation, it is evident that at least one fossil starfish found the bristly meal too tempting to pass up.