title: Anatomic geometry of sound transmission and reception in Cuvier's beaked whale (Ziphius cavirostris).
abstract: This study uses remote imaging technology to quantify, compare, and contrast the cephalic anatomy between a neonate female and a young adult male Cuvier's beaked whale. Primary results reveal details of anatomic geometry with implications for acoustic function and diving. Specifically, we describe the juxtaposition of the large pterygoid sinuses, a fibrous venous plexus, and a lipid-rich pathway that connects the acoustic environment to the bony ear complex. We surmise that the large pterygoid air sinuses are essential adaptations for maintaining acoustic isolation and auditory acuity of the ears at depth. In the adult male, an acoustic waveguide lined with pachyosteosclerotic bones is apparently part of a novel transmission pathway for outgoing biosonar signals. Substitution of dense tissue boundaries where we normally find air sacs in delphinoids appears to be a recurring theme in deep-diving beaked whales and sperm whales. The anatomic configuration of the adult male Ziphius forehead resembles an upside-down sperm whale nose and may be its functional equivalent, but the homologous relationships between forehead structures are equivocal.
authors.affiliation: Department of Biology, San Diego State University, San Diego, California, USA. tcranfor@mail.sdsu.edu
authors.forename: Ted W
authors.initials: TW
authors.lastname: Cranford
authors.forename: Megan F
authors.initials: MF
authors.lastname: McKenna
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Soldevilla
authors.forename: Sean M
authors.initials: SM
authors.lastname: Wiggins
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Goldbogen
authors.forename: Robert E
authors.initials: RE
authors.lastname: Shadwick
authors.forename: Petr
authors.initials: P
authors.lastname: Krysl
authors.forename: Judy A
authors.initials: JA
authors.lastname: St Leger
authors.forename: John A
authors.initials: JA
authors.lastname: Hildebrand
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000818:Animals; D001306:Auditory Pathways / Q000033:anatomy & histology; D002508:Cephalometry / Q000295:instrumentation; D005260:Female; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D008297:Male; D010256:Paranasal Sinuses / Q000033:anatomy & histology; D012727:Sex Characteristics; D012886:Skull / Q000033:anatomy & histology*; D019291:Skull Base / Q000033:anatomy & histology; D013018:Sound Spectrography; D013100:Sphenoid Bone / Q000033:anatomy & histology; D014828:Vocalization, Animal / Q000502:physiology*; D014907:Whales / Q000033:anatomy & histology* / Q000502:physiology