Crinoids, commonly known as sea lilies and feather stars, are abundant and diverse in many marine environments. Yet, because they are difficult to maintain and have never been bred in aquaria, and because many species are known from few specimens, they remain among the least understood of marine animals. Recognition of crinoid species is particularly ambiguous. Yet, accurate identification of these animals is critical for understanding their extensive fossil record and their roles in marine ecosystems, where some may signal environmental change, and collecting specimens as potential sources of new pharmaceuticals. Building on previous award results, we will focus on three named species of Comaster and on the highly variable Phanogenia gracilis, to clarify what constitutes a crinoid species using additional data provided by Greg Rouse (South Australian Museum). Both are widespread Pacific reef-dwellers. We will compare how DNA sequences in two genes vary relative to currently used physical diagnostic traits. Much of a crinoid is plankton-feeding apparatus, which varies with growth and environmental conditions. Sequences should be similar within a species and differ between species. We also propose to analyze larger numbers of specimens from different geographic areas in order to identify genetic populations, which have not been investigated for any crinoid. We thus hope to reconstruct their geographic evolutionary history, and assess levels of genetic biodiversity. Analytical methods will follow protocols already used successfully by us to study crinoids and other organisms. We expect to produce at least two peer-reviewed scientific journal articles and two conference presentations. The collaborative component consists of a lecture series and hands-on laboratory for University School science students covering 1) taxonomy, evolution and the species concept, 2) crinoid ecology, 3) crinoids in the history of deep-sea exploration, and laboratory exercises in analysis of deep-sea skeletal remains using crinoids as a model.