ABOUT DRP
PEOPLE
CAREERS
PARTNERSHIPS
SCIENCE RESEARCH
 » I. Research System
 » II. Research Methods
 » A. Phylogenetics
 » B. Morphometrics
 » C. SEM
 » D. X-Radiology
 » E. Development Experiments
 » F. Field Research
 » III. Caribbean Biodiversity Research
SCIENCE EDUCATION
TEACHER WORKSHOPS
MULTIMEDIA RESOURCES

Our Scanning Electron Microscopy and Hard-Tissue Histology research is used to study shell composition (microstructure) and biomineralization patterns through ontogeny and phylogeny . Shell microstructural features provide species-diagnostic characters and are indicative of how shell form is assembled compositionally during growth (Hickman, 1996). Standard Scanning Electron Microscopy is used to examine the preserved record of shell growth (juvenile to adult) in both living and fossil shells. Hard tissue histology studies (shell thin-sections) complement SEM studies, determine the quantitative differences in the volume of shell materials among ancestors and descendents, and document patterns of shell deposition. Both approaches permit an analysis of constructional and compositional changes in development through geological time.

Multiple features of the Prunum shell are appropriate for developmental analysis via SEM and thin sectioning: the shell whorls, external varix, inner lip, posterior and dorsal lip callus, anterior aperture margin callus, and posterior aperture margin callus. Preliminary research (Nehm, 2001b) has indicated that the primary shell whorls are comprised of (from the exterior to the interior of the shell) simple prismatic, comarginal crossed lamellar, and radial crossed lamellar layers. In addition, a thick inner comarginal crossed lamellar layer may be present or absent depending on the species. Between species the number of shell layers is known to vary among shells of different sizes and shapes. We are currently using SEM and thin sectioning to investigate constructional and compositional patterns of shell evolution in the Dominican Republic Neogene (primarily in the Gurabo and Cana Rivers ).