Meeting Abstract

48.6  Sunday, Jan. 5 11:15  Finger on the Pulse: Evidence for Magnetite-Based Magnetoreceptors in the Caribbean Spiny Lobster ERNST, D.A.*; GENTRY, K.; LOHMANN, K.J.; University of North Carolina at Chapel Hill dernst@live.unc.edu

The Earth’s magnetic field plays an important role in guiding diverse species by providing both directional (compass) and positional (map) information. However, the transduction mechanisms that underlie magnetic field detection have not been clearly established in any animal. One hypothesis proposes that crystals of the mineral magnetite function as receptors for the magnetic sense. By twisting into alignment with the geomagnetic field, single-domain magnetite crystals may activate secondary receptors or open ion channels. Magnetic material thought to be magnetite has been detected in the Caribbean spiny lobster (Panulirus argus), the only invertebrate known to possess both a magnetic compass and a magnetic map. To determine if these magnetic particles are associated with magnetoreception, lobsters were subjected to strong, pulsed magnetic fields capable of re-aligning the magnetic moment of biogenic magnetite crystals. Lobsters were subjected to a pulsed field directed from posterior to anterior and either parallel to the geomagnetic horizontal component (North pulse) or antiparallel to it (South pulse). An additional group of control lobsters was handled but not pulsed. The following morning, lobsters were tethered within a water-filled arena and allowed to walk for 30 minutes at the capture location. Control lobsters were not significantly oriented as a group. In contrast, lobsters subjected to the North pulse oriented approximately west (mean angle = 259°). The South pulse group oriented approximately northeast (mean angle = 47°). The distributions of the two pulsed groups were significantly different. These results strongly suggest that spiny lobsters possess magnetoreceptors based on magnetite.