Meeting Abstract
Most generalist predators are faced with an assortment of preparation and handling decisions to make prior to consuming their prey. Octopuses commonly preying on mollusk and gastropod species that are protected by a calcified exoskeleton (shell), attempt to pull the shells apart or drill into the shell. This study was conducted to determine which feature of bivalve shells, shell thickness or adductor muscle strength, influenced the red octopus’ penetration techniques the most. Red octopuses (Octopus rubescens) were fed a single species of clam once a day over the course of 11 days and the handling time of each feeding trial was measured. Octopus rubescens presented with thin shelled (Nuttalia obscurata) vs. thick shelled (Venerupis philippinarum) bivalves, utilized different mechanisms for processing them. Octopuses used their tentacles and suckers to pull apart the thin shelled bivalves, but thick shelled bivalves, with nearly three times the pulling resistance of thin shelled bivalves, were more commonly drilled, presumably to inject paralyzing venom. Consequently, octopuses that drilled bivalve shells took 6.8 times longer to consume their prey than those that physically pulled the shells apart. Regardless of shell thickness, bivalve handling times continually decreased from day 1 to day 11 which suggests that O. rubescens uses a sophisticated working memory to learn and adjust their bivalve prey handling behavior. By using the “ideal” method for opening different types of bivalves, O. rubescens may be utilizing optimal foraging strategies when manipulating and processing bivalve prey.
