2004 Student Research Conference:
17th Annual Student Research Conference


Is Shell Shape a Valid Feature for Recognizing Physa halei as a Distinct Species of Snail?
Stephanie R. Toole
Dr. George L. Shinn, Faculty Mentor

In nature, shell shapes vary widely among freshwater snails, and traditionally, this has been the basis for distinquishing species. However, recent studies reveal that shell shape can be influenced by the presence of water-borne chemicals emanating from snail predators. Physa halei is reported by Wu et al., to be one of the most widespread freshwater snails in ponds and lakes of northern Missouri. It is easily recongized by the presence of a long broad aperture (very large body whorl) and a relatively short pointy spire (less then 1/4 of shell length). My breeding experiments with this species in the absence of predators show that it's offspring commonly have taller spires and narrower apertures than the parents, and would not be recognized as Physa halei. This indicates that Physa halei is not a valid species, but a morph of another Physa species.

Keywords: Physa halei, shell morphology, breeding experiments, freshwater snails


Presentation Type: Oral Paper

Session: 47-3
Location: VH 1010
Time: 4:15

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