Anatomic geometry of sound transmission and reception in Cuvier's beaked whale (Ziphius cavirostris).
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.
Cranford
Ted W
TW
Department of Biology, San Diego State University, San Diego, California, USA. tcranfor@mail.sdsu.edu
McKenna
Megan F
MF
Soldevilla
Melissa S
MS
Wiggins
Sean M
SM
Goldbogen
Jeremy A
JA
Shadwick
Robert E
RE
Krysl
Petr
P
St Leger
Judy A
JA
Hildebrand
John A
JA
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