Mathematical Biology Program

University of Utah
Department of Mathematics

Mathematical Biology Program


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Mathematical Biology seminar

David Carrier
Biology Department, University of Utah
"The Face That Sunk the Essex: Potential Function of the Spermaceti Organ in Aggression"
October 8
3:05pm in LCB 225

Herman Melville?s fictional portrayal of the sinking of the Pequod was inspired by instances in which large sperm whales sunk whaling ships by ramming the ships with their heads. Observations of aggression in species of the four major clades of cetaceans and the artiodactyl outgroup suggest that head-butting during male-male aggression is a basal behavior for cetaceans. We hypothesize that the ability of sperm whales to destroy stout wooden ships, three to five times their body mass, is a product of specialization for male-male aggression. Specifically, we suggest that the greatly enlarged and derived melon of sperm whales, the spermaceti organ, evolved as a battering ram to injure an opponent. To address this hypothesis we examined the correlation of relative melon size with the level of sexual dimorphism in body size among species of cetaceans. We also modeled impacts between two equal-sized sperm whales to determine if it is physically possible for the spermaceti organ to function as an effective battering ram. We found (1) that the evolution of relative melon size in cetaceans is positively correlated with the evolution of sexual dimorphism in body size, and (2) that the spermaceti organ of a charging sperm whale has enough momentum to seriously injure an opponent. These observations are consistent with the hypothesis that the spermaceti organ has evolved to be a weapon used in male-male aggression.

For more information contact J. Keener, 1-6089