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Author Koopman, Heather Natalie
Title The structure and function of the blubber of odontocetes
book jacket
Descript 408 p
Note Source: Dissertation Abstracts International, Volume: 63-09, Section: B, page: 4001
Supervisor: Andrew J. Read
Thesis (Ph.D.)--Duke University, 2001
Blubber is a unique adaptation for energy storage, thermoregulation, and mechanics in marine mammals, but little is known about its structure and specific functions for most species. I examined the morphology, ultrastructure, and biochemical composition of blubber and used these data to infer the function of this tissue in a range of odontocete species. Harbour porpoises ( Phocoena phocoena) are an interesting model for studying blubber structure and function in odontocetes, because their small size and demanding annual reproductive schedule, combined with the thermoregulatory challenges of a cold water habitat, place them on one end of the cetacean size/temperature/energy demand continuum. The characteristics of blubber were compared between juvenile porpoises in normal body condition with those known to have starved to death. In porpoises, starvation affects only the innermost layer of the blubber of the thorax, leaving the tailstock blubber and that of the outer layer of the thorax intact, in terms of blubber thickness, adipocyte size, and lipid composition. Therefore, less than 50% of the blubber is potentially mobilisable energy in harbour porpoises, and probably also in other small odontocetes. In female harbour porpoises, milk lipids are derived from dietary intake, rather than maternal blubber. Examination of levels of isovaleric acid in blubber across 30 species of toothed whales revealed that this unusual, toxic fatty acid accumulates in higher concentrations in the outer (superficial) layer of the blubber, and does so in an ontogenetic fashion. The presence of isovaleric acid may represent an adaptation that confers some advantage to odontocetes inhabiting cold water. Overall, the blubber structure of odontocetes is influenced by phylogeny, ontogeny and habitat. In all species examined, blubber is stratified so that dietary fatty acids are more abundant in the inner layer, and endogenously synthesised compounds dominate the outer layer. In beaked and sperm whales, triglycerides in blubber are gradually replaced by wax esters as animals grow, possible reflecting an adaptation to pressure and temperature. The blubber of odontocetes exhibits a high degree of variability in its composition and functions, reflecting the diversity in habitat, body size and life history of this suborder
School code: 0066
DDC
Host Item Dissertation Abstracts International 63-09B
Subject Biology, Animal Physiology
Biology, Zoology
0433
0472
Alt Author Duke University
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