Unique biochemical and mineral composition of whale ear bones.

Title

Unique biochemical and mineral composition of whale ear bones.

Creator

Kim Sora L; Thewissen J G M; Churchill Morgan M; Suydam Robert S; Ketten Darlene R; Clementz Mark T

Publisher

Physiological and biochemical zoology : PBZ

Date

2014
2014-08

Description

Abstract Cetaceans are obligate aquatic mammals derived from terrestrial artiodactyls. The defining characteristic of cetaceans is a thick and dense lip (pachyosteosclerotic involucrum) of an ear bone (the tympanic). This unique feature is absent in modern terrestrial artiodactyls and is suggested to be important in underwater hearing. Here, we investigate the mineralogical and biochemical properties of the involucrum, as these may hold clues to the aquatic adaptations of cetaceans. We compared bioapatites (enamel, dentine, cementum, and skeletal bone) of cetaceans with those of terrestrial artiodactyls and pachyosteosclerotic ribs of manatees (Sirenia). We investigated organic, carbonate, and mineral composition as well as crystal size and crystallinity index. In all studied variables, bioapatites of the cetacean involucrum were intermediate in composition and structure between those of tooth enamel on the one hand and those of dentine, cementum, and skeletal bone on the other. We also studied the amino acid composition of the cetacean involucrum relative to that of other skeletal bone. The central involucrum had low glycine and hydroxyproline concentrations but high concentrations of nonessential amino acids, unlike most bone samples but similar to the tympanic of hippos and the (pachyosteosclerotic) ribs of manatees. These amino acid results are evidence of rapid bone development. We hypothesize that the mineralogical and amino acid composition of cetacean bullae differs from that of other bone because of (1) functional modifications for underwater sound reception and (2) structural adaptations related to rapid ossification.

Subject

Amino Acids; Animals; Apatites; Artiodactyla/*anatomy & histology/*physiology; Bone and Bones/*chemistry; Ear/*anatomy & histology/*physiology; Minerals; Phylogeny; Trichechus/*anatomy & histology/*physiology; Whales/*anatomy & histology/*physiology

Identifier

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

576–584

Issue

4

Volume

87

Citation

Kim Sora L; Thewissen J G M; Churchill Morgan M; Suydam Robert S; Ketten Darlene R; Clementz Mark T, “Unique biochemical and mineral composition of whale ear bones.,” NEOMED Bibliography Database, accessed September 28, 2021, https://neomed.omeka.net/items/show/4147.

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