VIDAL, A.G.; CAIN, S.D.; Friday Harbor Labs, Univ. of Washington; Friday Harbor Labs, Univ. of Washington: Isolation of magnetic particles from the tissue of the sea slug, Tritonia diomedea

Several animals have been shown to orient using the Earth’s magnetic field. The sensory mechanisms underlying this ability, however, have not been determined. One proposed theory is based on the presence of biogenic magnetite particles within the tissues of animals. Although many animals have been shown to contain magnetite, the role of permanently magnetic material in magnetic orientation behavior remains unresolved. The nudibranch mollusc Tritonia diomedea has been shown to orient to earth-strength magnetic fields. T. diomedea has proven to be an excellent model to investigate the neural control of behavior due to its large, re-identifiable neurons and relatively simple nervous system. If we could reliably identify magnetic particles in this animal, we might be able to finally use electrophysiological techniques to determine what role magnetic material plays (if any) in magnetoreception. The results of previous attempts to determine whether T. diomedea contains biogenic magnetite, however, were ambiguous. In this study, we used modifications of mineral extraction techniques to isolate magnetic material from T. diomedea. Preliminary results indicate that these animals do indeed contain permanently magnetic material. This material was further localized to the foot, lateral body wall, and oral veil. We are currently using TEM, EDX, and electron diffraction to identify the composition of the magnetic material. Although the presence of magnetic material itself doesn’t prove a role in magnetoreception, its presence and localization in a model neuro-ethological animal will allow us to design effective electrophysiological experiments to investigate whether magnetic material is involved in magnetic field transduction.