Meeting Abstract

P3.11  Jan. 6  INFORMATION ENCODED IN THE EARLY ONTOGENETIC SHELLS OF PLANKTONIC GASTROPOD LARVAE: KELLETIA KELLETII AS A MODEL FOR PALEOBIOLOGICAL INFERENCE VENDETTI, Jann; Univ. of California, Berkeley jannv@berkeley.edu

The developmental mode of extant and extinct gastropod taxa can be inferred from morphological characters of the gastropod larval shell. Planktotrophy, lecithotrophy, and direct modes of development are identified by larval shell size, shape, ornamentation, and microstructure. The sequence of onset of these characters and their extent during the life of gastropod larvae can be additionally informative and powerful in identifying life history traits in fossil gastropod faunas. In this study, larval characters in the buccinid gastropod Kelletia kelletii, a subtidal Pacific coast species with free-swimming planktonic veliger larvae, were observed using Scanning Electron Microscopy (SEM). Detailed images revealed the early ontogenetic characters of shell microstructure, calcification, changes in shell shape, and the appearance of distinctive features during ontogeny. The Buccinid family of gastropods, which includes K. kelletii, contains taxa with a variety of developmental modes. All buccinids begin development within a benthic egg capsule, which can house a single embryo or as many as one thousand. While encapsulated, larvae of some species consume intra-capsular albumen while others ingest nurse eggs. At hatching, buccinid embryos either emerge as crawl-away juveniles (direct development) or as swimming veligers. These distinct modes of development necessarily influence the morphology of embryonic and larval shells and impart on them characters that can be identified and recognized in related taxa and fossil larval shells.