Ontogeny and organization of acoustic lipids in jaw fats of the bottlenose dolphin (Tursiops truncatus)
- UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
- Zoey Patricia Zahorodny (Creator)
- Institution
- The University of North Carolina Wilmington (UNCW )
- Web Site: http://library.uncw.edu/
- Advisor
- Heather Koopman
Abstract: Specialized acoustic fat bodies located around the mandibles of odontocetes
have the proposed role of focusing received sound towards the ear. Previous
studies have suggested that the distribution of lipids in these fat bodies may form
a waveguide for incoming sound. In bottlenose dolphins (Tursiops truncatus)
these fat bodies are comprised of triacylglycerols (TAG) and wax esters (WE).
Fine-scale topographic distribution and rapid ontogenetic accumulation of
branched-chain (iso) fatty acids (FA) in jaw fat and cranial blubber of bottlenose
dolphins (n=10) are described here. Iso-acids are unusual endogenous lipids
formed as byproducts of amino acid breakdown and have a hypothesized role in
sound transmission. Isovaleric acid (i-5:0) is toxic to most mammals, so the
considerable presence of this FA in dolphin acoustic tissues represents an
unusual physiological trait. Iso-acids were the dominant FA constituents in jaw
fat, often comprising up to 80 wt%. Fetal concentration of i-5:0 was extremely
low (<3 wt%) compared to adults (up to 52 wt%), and calves and subadults
exhibited intermediate values. Little FA variation was found in adult inner jaw fat
except for reduced values of iso-acids at the dorsal-most region along the length
of the fat body. Adult outer jaw fat had highest iso-acid accumulation over the
thinnest region (pan bone) of the mandible, with low iso-acid values at the dorsalmost
regions sampled. In all animals, blubber contained very low levels of isoacids.
The notable exception was a small area of blubber on the lateral
mandibular region overlying Norris’ “acoustic window”. Blubber here exhibited up
to a 10-fold increase in iso-acids compared to adjacent blubber. This acoustic window blubber is thus more chemically similar to acoustic mandibular fat, than
to body blubber, and likely confers less impedance to sound waves. Young
animals showed rapid accumulation of i-5:0 and i-15:0 in acoustic tissues and
variation in iso-acid accumulation across age classes was described by
logarithmic curves which accounted for upwards of 68% of variation. Patterns of
lipid distribution of inner and outer jaw fat were apparent in animals as young as
calves, while patterns were apparent in cranial tissues even earlier; at the fetal
stage.
Ontogeny and organization of acoustic lipids in jaw fats of the bottlenose dolphin (Tursiops truncatus)
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Additional Information
- Publication
- Thesis
- A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
- Language: English
- Date: 2009
- Keywords
- Bottlenose dolphin--Morphology, Bottlenose dolphin--Physiology, Lipids--Research
- Subjects
- Bottlenose dolphin -- Physiology
- Bottlenose dolphin -- Morphology
- Lipids -- Research