Meeting Abstract

101.3  Thursday, Jan. 7  Discrete odor sampling of the Oregon shore crab Hemigrapsus oregonensis during ontogeny WALDROP, LD; Univ. of California, Berkeley lwaldrop@berkeley.edu

Crabs, like many malacostracan crustaceans, sense chemical signals in their fluid surroundings using chemosensory hair arrays on antennules to discretely sample odor-laden fluid (sniffing). Sniffing occurs when a quick downstroke of the antennule forces water to flow in between the hairs of the array and a slower return stroke traps fluid within the array. Sniffing is a critical part of olfaction for not only adult crabs but for juvenile crabs which can be up to two orders of magnitude smaller than adults. Since sniffing in crabs relies heavily on a narrow range of antennule velocities and dimensions in order to effectively capture and hold fluid, are juvenile crabs that are significantly smaller able to sniff during ontogeny? To address this question, antennule kinematics were recorded using high speed videography and antennule morphologies were examined using scanning electron micrographs from Oregon shore crabs Hemigrapsus oregonensis ranging in size from 4 to 28 mm carapace width. These data were used to both characterize allometric growth patterns from juveniles to adults and to construct dynamically-scaled physical models of antennules representing animals at different stages of growth. Particle image velocimetry (PIV) was used to visualize fluid flow in the hair array of each model during realistic antennule movement to determine if each stage could discretely sample odors. The scaling relationships of antennule kinematics and morphology and PIV results will be presented.