MICROWEAR ANALYSIS OF CRAB CLAWS; A FUNCTIONAL MORPHOLOGICAL APPROACH

Traditionally, microwear analyses have focused on scratches, pits, and other scars on the surface of the teeth of vertebrates. These methods have proven effective in reconstructing the diet of extinct and extant taxa. Such studies have been completed on a wide range of vertebrates, including conodonts, fish, non-avian dinosaurs, and mammals, exhibiting the versatility of microwear analysis. This study applies the methods used in dental microwear analyses to study the potential functional and taphonomic significance of wear patterns on the claws of the Florida stone crab, Menippe mercenaria Say, 1818. Molds are made of the inner and outer claw surfaces, as well as the denticles using a high resolution polyvinylsiloxane compound, and casts are poured using epoxy resin. The study area was standardized by selecting the center of each claw finger molded. This procedure is used extensively in dental microwear studies. Scanning electron microscopy (SEM) in conjunction with the semi-automated software Microware 4.02 is used to quantify wear marks seen on cuticle. Patterns in wear are then determined and an attempt is made to relate them to functional morphology. Number of scratches, mean scratch length, and angular dispersion will be the primary factors used to make interpretations. Some differences are important to note, such as the varying hardness of decapod cuticle, as well as its softness in relation to enamel and dentine. Also, the function of claws is very different from the role teeth occupy in the life of vertebrates. Decapod claws function to capture food, to manipulate food toward the mouthparts, and to defend against predators; claws do not masticate the food. Taphonomic effects on wear marks are being investigated by tumbling a modern Menippe claw in sediment for set time intervals, which will be followed by an SEM investigation using modern crab claws and fossil specimens. This study is, to the author’s knowledge, the first of its kind attempted on an invertebrate taxon.