Crab Dentition Patterns and Impacts on Their Diet

Abstract

Morphological and mechanical features of crab claws reflect their functions and prey selections. This study focuses on the phylogenetic dentition patterns of crabs and the impacts it has on prey consumption. Pictures of crab carapace and the right claw were imported to Image J to measure aspect ratio, radius of curvature, propus length, and denticle position for each denticle as well as the carapace length. Generalist species such as Oregonia gracilis tend to have a smaller radius of curvature and a larger aspect ratio. The specialists’ species such as Pugettia richii, Pugettia gracilis, Pugettia producta, Metacarcinus magister, Cancer productus, Cancer oregonensis, Telmessus cheiragonus, Scyra acutifrons, and Hemigrapsus nudus have a larger radius of curvature and a smaller aspect ratio. Generalist species commonly eat small soft marine organisms and macro algae, while the specialist species consume hard-shelled prey, such as barnacles, clams, snails, etc. Most specialist species have wider, blunter denticles at the fulcrum and become narrower, sharper towards the tip. The mechanical advantages for these crab species comes from the tip of the claw; allowing them to crush their prey. Generalist species have sharper, narrower teeth from the fulcrum to the tip of the claw. These crabs do not use their claws for crushing, but more for shredding. Denticle position and mechanical advantages heavily impact the dietary and foraging behaviors of the crabs studied. The data collected from this research could potentially jump start research on crab dentition. By understanding the use of crab denticles, we will have a greater advantage to studying crab foraging behaviors and denticle morphologies.