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Title: The anatomy and physiology of the crab balancing organ
Author: Findlay, Robin
ISNI:       0000 0001 3465 0608
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1985
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This thesis examines the way in which the crab balancing organ detects low frequency angular accelerations and vibrations. Anatomical studies using light and electron microscopy have confirmed that the statocyst comprises two fluid-filled orthogonal canals in which the sensory elements are long thin hairs (thread hairs) or short hooked hairs (free hook hairs and statolith hairs) which poke into the lumen of the canals. The thread hairs are innervated by two bipolar neurones which send their dendritic processes into modified chordotonal organs; these are characterised by the presence of scolopidial elements accompanied by chitinous strands which link scolopidia with thread hairs. A linear systems technique, namely sinusoidal oscillation of the statocyst was used to examine the frequency response of the statocyst hair receptors in the range 0.6-78Hz. The thread hair/statocyst system is shown to behave as a velocity transducer in the range 0.6-4Hz. Free hook hair receptors also respond to low frequency sinusoids but their output is non-linear. Other nonlinearities exhibited by both receptors include gain adaptation and rectification of the response. In addition a marked position sensitivity is shown by the thread hair receptors. It is concluded that both types of receptor contribute to the detection of low frequency angular accelerations. A response to vibration is demonstrated by both types of receptor although the thread hairs respond only in a very transient way to frequencies above 30Hz. By contrast the free hook hair receptors respond throughout the vibration range tested and are suited to the detection of substrate and water borne signals. They have a best frequency between 30 and 40Hz.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Zoology