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Anatomy and physiology of the elasmobranch olfactory system

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Date Issued:
2011
Summary:
The olfactory system is the most highly developed system for molecular sensing in vertebrates. Despite their reputation for being particularly olfactory driven, little is known about how this sense functions in elasmobranch fishes. The goal of this dissertation was to examine the morphology and physiology of elasmobranchs to compare their olfactory system with teleost fishes and more derived vertebrates. To test the hypotheses that elasmobranchs possess greater olfactory sensitivities than teleosts and that lamellar surface area is correlated to sensitivity, I compared the surface area of the olfactory lamellae and the olfactory sensitivities of five phylogenetically diverse elasmobranch species. The olfactory thresholds reported here (10-9 to 10-6 M) were comparable to those previously reported for teleosts and did not correlate with lamellar surface area. Since aquatic species are subject to similar environmental amino acid levels, they appear to have converged upon similar amino acid sensitivities. To test the hypothesis that elasmobranchs are able to detect bile salt odorants despite lacking ciliated olfactory receptor neurons (ORNs), the type of ORN that mediates bile salt detection in the teleosts, I quantified the olfactory specificity and sensitivity of two elasmobranch species to four, teleost-produced C24 bile salts. Both species responded to all four bile salts, but demonstrated smaller relative responses and less sensitivity compared to teleosts and agnathans. This may indicate that elasmobranchs don't rely on bile salts to detect teleost prey. Also, the olfactory system of elasmobranchs contains molecular olfactory receptors for bile salts independent of those that detect amino acids, similar to teleosts.
Title: Anatomy and physiology of the elasmobranch olfactory system.
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Name(s): Meredith, Tricia L.
Charles E. Schmidt College of Science
Department of Biological Sciences
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Date Issued: 2011
Publisher: Florida Atlantic University
Physical Form: electronic
Extent: xiv, 120 p. : ill.
Language(s): English
Summary: The olfactory system is the most highly developed system for molecular sensing in vertebrates. Despite their reputation for being particularly olfactory driven, little is known about how this sense functions in elasmobranch fishes. The goal of this dissertation was to examine the morphology and physiology of elasmobranchs to compare their olfactory system with teleost fishes and more derived vertebrates. To test the hypotheses that elasmobranchs possess greater olfactory sensitivities than teleosts and that lamellar surface area is correlated to sensitivity, I compared the surface area of the olfactory lamellae and the olfactory sensitivities of five phylogenetically diverse elasmobranch species. The olfactory thresholds reported here (10-9 to 10-6 M) were comparable to those previously reported for teleosts and did not correlate with lamellar surface area. Since aquatic species are subject to similar environmental amino acid levels, they appear to have converged upon similar amino acid sensitivities. To test the hypothesis that elasmobranchs are able to detect bile salt odorants despite lacking ciliated olfactory receptor neurons (ORNs), the type of ORN that mediates bile salt detection in the teleosts, I quantified the olfactory specificity and sensitivity of two elasmobranch species to four, teleost-produced C24 bile salts. Both species responded to all four bile salts, but demonstrated smaller relative responses and less sensitivity compared to teleosts and agnathans. This may indicate that elasmobranchs don't rely on bile salts to detect teleost prey. Also, the olfactory system of elasmobranchs contains molecular olfactory receptors for bile salts independent of those that detect amino acids, similar to teleosts.
Summary: In some elasmobranch species, each olfactory bulb (OB) is physically partitioned into two hemi-bulbs; however, the functional significance of this morphology is not fully understood. The organization of the OBs in three species with varying OB morphologies was examined to test the hypothesis that the elasmobranch OB is somatotopically arranged. Glomeruli in the OB received projections from ORNs in 3-4 olfactory lamellae situated immediately anterior. These results indicate a somatotopic arrangement of the elasmobranch OB, which may be unique among vertebrate olfactory systems and potentially led to the hemi-OB morphology.
Identifier: 775598880 (oclc), 3333058 (digitool), FADT3333058 (IID), fau:3801 (fedora)
Note(s): by Tricia L. Meredith.
Thesis (Ph.D.)--Florida Atlantic University, 2011.
Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.
Subject(s): Condrichthyes -- Sense organs
Condrichthyes -- Physiology
Sharks -- Physiology
Adaptation (Biology)
Aquatic animals -- Physiology
Persistent Link to This Record: http://purl.flvc.org/FAU/3333058
Use and Reproduction: http://rightsstatements.org/vocab/InC/1.0/
Host Institution: FAU