The isolation of prey identification substances that are utilized by garter snakes

Garter snakes (Thamnophis sirtalis) identify food sources by chemical compounds obtained from prey. Analysis of garter snake prey chemicals was conducted on earthworms (Lumbricus terrestris), fathead minnows (Pimephaies promelas). and mosquito fish (Gambusia affina) in order to isolate and analyze these chemical substances. The substances were isolated from the prey by a variety of extraction techniques and chromatography methods in conjunction with a snake bioassay procedure. The snake bioassay procedure consisted of presenting prey derived chemicals to garter snakes on cotton swabs and observing tongue flicking and attacks. Sugar analysis was conducted by gas chromatography and gas chromatography mass spectrometry. Proton and carbon nuclear magnetic resonance, amino acid analysis, and molecular weight estimates were also implemented to analyze these chemical substances.

There were numerous similarities among the different substances isolated from each prey. The carbon and proton nuclear magnetic resonance spectra obtained from the isolated substances of the earthworm and fathead minnow resulted in very similar spectra. The earthworm and fathead minnow substances also resulted in similar sugar and amino acid contents with approximately the same molecular weight components. It was concluded that the active substances isolated from the fathead minnow and the earthworm had very similar chemical and physical properties even though the substances were isolated from different phyla found in different environments.