Meeting Abstract
The blue crab literature currently lacks a description of the ultrastructure, composition, and molt cycle dynamics of the medial tooth, a siliceous structure located within the gastric mill on the distal portion of the urocardiac ossicle. Examples of mineralization of siliceous structures in the Crustacea have been a largely understudied phenomenon, with exception to opal teeth of copepods (Michels et al. 2012, Miller et al. 1990) and the amphipods (Mekhanikova et al. 2012). Development of mineralized structures, and more specifically feeding structures, through the molt cycle is critical for acquisition of nutrients to aid in growth and development of the organism. Here we examine the dynamics of silicification of the medial tooth in the gastric mill of the blue crab, Callinectes sapidus. Scanning electron microscopy was utilized to examine surface structural features of the medial tooth, in tandem with energy dispersive x-ray analysis for compositional information. These data revealed degradation of the old tooth during the premolt stages, along with elaboration of the new siliceous layer through late premolt into post molt. Furthermore, conical projections are apparent on the outer surface of the exocuticle, and appear to contribute to deposition. A variety of histological preparations across various stages of the molt cycle were examined in order to compare the cellular changes and characteristic features of tissue surrounding the medial tooth to those features and changes that occur during calcification of the cuticle. These novel data provide the first description of the medial tooth of the blue crab, as well as a foundation for uncovering structural and cellular similarities and differences in two essential mineralization processes: calcification and silicification. The study was supported by grant 2014-1751 from North Carolina Sea Grant.
