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Perception & Use of Magnetic Field Information in Navigation Behaviors in Elasmobranch Fishes.

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Title:Perception & Use of Magnetic Field Information in Navigation Behaviors in Elasmobranch Fishes.
Authors:Anderson, James M.
Contributors:Zoology (department)
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Date Issued:Aug 2018
Publisher:University of Hawaiʻi at Mānoa
Abstract:Three principal hypotheses prevail regarding the sensory means by which animals, including elasmobranchs, perceive and use magnetic field information. Of these three hypotheses, the iron (magnetite) based magnetoreceptor hypothesis is regarded as being the most basal, and is proposed to be conserved across taxa, from invertebrates through to high vertebrates. Magnetoreception via magnetic-electric induction and the radical pairs mechanism is considered more derived. Modern elasmobranch and teleost fish share a common ancestry. Although they evolved independently, the apparent evolutionary conservation of functional magnetite containing structures (as in teleosts and birds) might suggest such structures are also present in the elasmobranchs.
Elasmobranch fishes have been both hypothesized and empirically shown to respond to changes in magnetic fields. However, empirical evidence to support orientation and navigation via magnetic field information in elasmobranch fishes is scant; sensory acuity to magnetic stimuli is undescribed, and the physical mechanisms and sensory pathways by which sharks may perceive and use magnetic information continue to be the subject of debate.
The investigations detailed in the following chapters aim to examine the ability of sharks to perceive and use magnetic field information in navigation behaviors. Using conditioned behavior experiments as a proxy, these experiments confirm sharks’ ability to perceive magnetic stimuli, quantify sensory acuity, determine ability to discriminate contrasting magnetic stimuli, and provide insight into the possible mechanisms used. Morphological and physiological analyses aimed to identify critical structures required for an elasmobranch homologue to the iron/magnetite based olfactory magnetoreceptor described in teleost fish.
Sharks were able to perceive magnetic field changes as low as 0.03 microtesla (μT), and could repeatedly and reliably discriminate between contrasting but similar magnetic landmarks. This demonstrates sharks could not only perceive ecologically relevant magnetic stimuli, but could learn, internalize and organize that information – a key
component in the formation of a cognitive map, required in navigation. Sensory deprivation/impairment techniques incorporated suggested the likely use of at least two sensory mechanisms (magnetic-electric induction & a putative magnetite based magnetoreceptor). Finally, morphological and physiological investigations suggest sharks possess the critical structures required in a magnetite-based olfactory housed magnetoreceptor.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018.
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Zoology

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