Architecture of the sperm whale forehead facilitates ramming combat

Panagiotopoulou, Olga, Spyridis, Panagiotis, Mehari Abraha, Hyab, Carrier, David R. and Pataky, Todd C. (2015) Architecture of the sperm whale forehead facilitates ramming combat. PeerJ PrePrints, . doi:10.7287/peerj.preprints.1590v1

Author Panagiotopoulou, Olga
Spyridis, Panagiotis
Mehari Abraha, Hyab
Carrier, David R.
Pataky, Todd C.
Title Architecture of the sperm whale forehead facilitates ramming combat
Journal name PeerJ PrePrints
Publication date 2015-12-17
Year available 2015
Sub-type Article (original research)
DOI 10.7287/peerj.preprints.1590v1
Open Access Status DOI
Place of publication London, United Kingdom
Publisher PeerJ
Language eng
Formatted abstract
Herman Melville’s novel Moby Dick was inspired by historical instances in which large sperm whales (Physeter macrocephalus L.) sank 19th century whaling ships by ramming them with their foreheads. The immense forehead of sperm whales is possibly the largest, and one of the strangest, anatomical structures in the animal kingdom. It contains two large oil-filled compartments, known as the “spermaceti organ” and “junk”, that constitute up to one-quarter of body mass and extend one-third of the total length of the whale. Recognized as playing an important role in echolocation, previous studies have also attributed the complex structural configuration of the spermaceti organ and junk to acoustic sexual selection, acoustic prey debilitation, buoyancy control, and aggressive ramming. Of these additional suggested functions, ramming remains the most controversial, and the potential mechanical roles of the structural components of the spermaceti organ and junk in ramming remain untested. Here we explore the aggressive ramming hypothesis using a novel combination of structural engineering principles and probabilistic simulation to determine if the unique structure of the junk significantly reduces stress in the skull during quasi-static impact. Our analyses indicate that the connective tissue partitions within the junk reduce stress across the skull during impact; stress reduction is greatest in the anterior aspect of the skull; and removal of the connective tissue partitions increases stress concentrations on the tip of the skull, possibly making it prone to fracture. Although the unique structure of the junk certainly serves multiple functions, our results are consistent with the hypothesis that the structure also evolved to function as a massive battering ram during male-male competition.
Q-Index Code CX
Q-Index Status Provisional Code
Institutional Status UQ
Additional Notes Article is a pre-print of UQ:384151, but has been published in a separate journal.

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biomedical Sciences Publications
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Created: Thu, 07 Apr 2016, 14:26:25 EST by Olga Panagiotopoulou on behalf of School of Biomedical Sciences