Meeting Abstract
S7-2.3 Saturday, Jan. 5 Does Form Follow Flow? Crayfish Aesthetasc Morphology, Arrangement, And Flow Environment. MEAD, K. S.; Denison Univ., Granville OH meadk@denison.edu
Crayfish sample their olfactory environment by flicking their antennules in a rapid down stroke followed by a slower return stroke. This motion thins the boundary layer surrounding chemosensory structures, facilitating encounter with odor molecules. Ambient current and the shape and arrangement of the sensors also affect the thickness of the boundary layer coating the sensors, and thus the sensors� ability to extract chemical information from the environment. Animals from different flow environments have chemical sensors that are shaped to capture odors efficiently in that particular habitat. Antennule and aesthetasc length, diameter, spacing, and insertion angle were compared among museum specimens from 43 distinct populations of the crayfish Orconectes virilis collected from river (n=21), creek (n=10) or lake (n=12) habitats. Structural parameters were measured from SEM micrographs and analyzed using ANOVAs. Although variation was high, the mean aesthetasc length was longer in lake O. virilis (113 ± 10 &mu m) than in creek (108 ± 8 &mu m) or river (105 ± 10 &mu m) crayfish. Lake animals had aesthetascs that were attached to the antennule at a larger angle relative to the supporting antennule (43 ± 4°) than animals from creeks (29 ± 4°) or rivers (33 ± 3°). Furthermore, aesthetascs from lake animals were more spaciously arranged than aesthetascs from creek or river populations. The greater aesthetasc length and insertion angle extend the receptor-laden portion of the sensor beyond the boundary layer of slow-moving fluid created by the antennule, allowing water containing odorant molecules to be accessed by the sensors. The more spacious arrangement of aesthetascs further enhances odor penetration into aesthetasc arrays of lake animals.
