The face that sank the Essex: potential function of the spermaceti organ in aggression

2002 ◽  
Vol 205 (12) ◽  
pp. 1755-1763
Author(s):  
David R. Carrier ◽  
Stephen M. Deban ◽  
Jason Otterstrom
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Potential Function ◽  
Body Mass ◽  
Sperm Whale ◽  
Sperm Whales ◽  
Male Aggression ◽  
Moby Dick ◽  
The Face

SUMMARY `Forehead to forehead I meet thee, this third time, Moby Dick!' [Ahab (Melville, 1851)] Herman Melville's fictional portrayal of the sinking of the Pequodwas inspired by instances in which large sperm whales sank whaling ships by ramming the ships with their heads. Observations of aggression in species of the four major clades of cetacean 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, 3-5 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 between relative melon size and the level of sexual dimorphism in body size among cetaceans. We also modeled impacts between two equal-sized sperm whales to determine whether it is physically possible for the spermaceti organ to function as an effective battering ram. We found (i) that the evolution of relative melon size in cetaceans is positively correlated with the evolution of sexual dimorphism in body size and (ii) 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.

scholarly journals An Unparalleled Sexual Dimorphism of Sperm Whale Encephalization

2016 ◽  
Vol 29 ◽  
Author(s):  
Bruno Cozzi ◽  
Sandro Mazzariol ◽  
Michela Podestà ◽  
Alessandro Zotti ◽  
Stefan Huggenberger
Keyword(s):  
Sexual Dimorphism ◽  
Body Mass ◽  
Social Evolution ◽  
Brain Size ◽  
Mammalian Species ◽  
Large Body ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Adult Males ◽  
Sperm Whales

The sperm whale Physeter macrocephalus (Linnaeus, 1758) is the largest toothed whales and possesses the highest absolute values for brain weight on the planet (together with the killer whale Orcinus orca). Former calculations of the encephalization quotient (EQ), which is used to compare brain size of different mammalian species, showed that the sperm whale brain is smaller than expected for its body mass. However, the data reported in the literature and formerly used to calculate the sperm whale EQ suffered from a potential bias due to the tendency to measure mostly larger males of this extreme sexually dimorphic species. Accordingly, we found that the brains of female sperm whales are close to the absolute weight range of the males, but, given the much lower body mass of females, their EQ results more than double of what reported before for the whole species, and is thus nearly into the primate range (female EQ = 1.28, male EQ = 0.56). This sexual dimorphism is unique among mammals. Female sperm whales live in large families in which social interactions and inter-individual communication are essential, while adult males live solitarily. Thus the particular sex-specific behavior of SWs may have led to a maternally-driven social evolution, and eventually contributed to achieve female EQ values (but not male EQs) among the highest ever calculated for mammals with respect to their large body mass.

scholarly journals Architecture of the sperm whale forehead facilitates ramming combat

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1895 ◽  
Author(s):  
Olga Panagiotopoulou ◽  
Panagiotis Spyridis ◽  
Hyab Mehari Abraha ◽  
David R. Carrier ◽  
Todd C. Pataky
Keyword(s):  
Connective Tissue ◽  
Structural Engineering ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Moby Dick ◽  
Unique Structure ◽  
Complex Structural ◽  
Von Mises ◽  
Von Mises Stresses

Herman Melville’s novelMoby Dickwas 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 in the junk reduce von Mises stresses across the skull and that the load-redistribution functionality of the former is insensitive to moderate variation in tissue material parameters, the thickness of the partitions, and variations in the location and angle of the applied load. Absence of the connective tissue partitions increases skull stresses, particularly in the rostral aspect of the upper jaw, further hinting of the important role the architecture of the junk may play in ramming events. Our study also found that impact loads on the spermaceti organ generate lower skull stresses than an impact on the junk. Nevertheless, whilst an impact on the spermaceti organ would reduce skull stresses, it would also cause high compressive stresses on the anterior aspect of the organ and the connective tissue case, possibly making these structures more prone to failure. This outcome, coupled with the facts that the spermaceti organ houses sensitive and essential sonar producing structures and the rostral portion of junk, rather than the spermaceti organ, is frequently a site of significant scarring in mature males suggest that whales avoid impact with the spermaceti organ. 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.

scholarly journals Architecture of the sperm whale forehead facilitates ramming combat

2015 ◽  
Author(s):  
Olga Panagiotopoulou ◽  
Panagiotis Spyridis ◽  
Hyab Mehari Abraha ◽  
David R Carrier ◽  
Todd C Pataky
Keyword(s):  
Connective Tissue ◽  
Stress Reduction ◽  
Structural Engineering ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Stress Concentrations ◽  
Moby Dick ◽  
Unique Structure ◽  
Complex Structural

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.

Ecological and evolutionary significance of sizes of giant extinct kangaroos

2006 ◽  
Vol 54 (4) ◽  
pp. 293 ◽  
Author(s):  
Kristofer M. Helgen ◽  
Rod T. Wells ◽  
Benjamin P. Kear ◽  
Wayne R. Gerdtz ◽  
Timothy F. Flannery
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Body Mass ◽  
Size Variation ◽  
Evolutionary Significance ◽  
Congeneric Species ◽  
Size Classes ◽  
Grey Kangaroo ◽  
Show Evidence

A method, based on femoral circumference, allowed us to develop body mass estimates for 11 extinct Pleistocene megafaunal species of macropodids (Protemnodon anak, P. brehus, P. hopei, P. roechus, Procoptodon goliah, ‘P.’ gilli, Simosthenurus maddocki, S. occidentalis, Sthenurus andersoni, S. stirlingi and S. tindalei) and three fossil populations of the extant eastern grey kangaroo (Macropus giganteus). With the possible exception of P. goliah, the extinct taxa were browsers, among which sympatric, congeneric species sort into size classes separated by body mass increments of 20–75%. None show evidence of size variation through time, and only the smallest (‘P.’ gilli) exhibits evidence suggestive of marked sexual dimorphism. The largest surviving macropodids (five species of Macropus) are grazers which, although sympatric, do not differ greatly in body mass today, but at least one species (M. giganteus) fluctuated markedly in body size over the course of the Pleistocene. Sexual dimorphism in these species is marked, and may have varied through time. There is some mass overlap between the extinct and surviving macropodid taxa. With a mean estimated body mass of 232 kg, Procoptodon goliah was the largest hopping mammal ever to exist.

scholarly journals Pelvic sexual dimorphism among species monomorphic in body size: relationship to relative newborn body mass

2015 ◽  
Vol 97 (2) ◽  
pp. 503-517 ◽  
Author(s):  
Robert G. Tague
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Body Mass ◽  
Castor Canadensis ◽  
Published Data ◽  
Sciurus Carolinensis ◽  
Sylvilagus Floridanus ◽  
Lower Prevalence ◽  
Joint Fusion ◽  
Pelvic Sexual Dimorphism

Abstract Females have larger pelves than males among eutherians to mitigate obstetrical difficulty. This study addresses 3 issues concerning pelvic sexual dimorphism using 8 species that are sexually monomorphic in nonpelvic size: Aotus azarae , Castor canadensis , Dasypus novemcinctus , Hylobates lar , Saguinus geoffroyi , Sciurus carolinensis , Sylvilagus floridanus , and Urocyon cinereoargenteus . Using published data to compute the index of relative newborn body mass (RNBM = [newborn body mass/adult female body mass]100%) for 266 eutherian species, A. azarae , H. lar , and S. geoffroyi are characterized as giving birth to relatively large newborns and the other 5 species as giving birth to relatively small newborns. The 3 issues are, compared to species giving birth to relatively small newborns, whether species that give birth to relatively large newborns have 1) higher magnitude of pelvic sexual size dimorphism (SSD), 2) lower prevalence of pelvic joint fusion, and 3) dissociation between pelvic and nonpelvic sizes. Nine measures of the pelvis were taken, and fusion of interpubic and sacroiliac joints was observed. Species grouped by high and low RNBM do not differ significantly in magnitude of SSD of pelvic inlet circumference. Species with high RNBM have significantly lower prevalence of interpubic joint fusion than those with low RNBM. Sexes do not differ in their multiple correlation coefficients between inlet circumference and nonpelvic body size in 7 of 8 species. Results suggest that 1) there are multiple anatomical pathways for pelvic obstetrical sufficiency, 2) an unfused interpubic joint is obstetrically advantageous, and 3) relative newborn size does not change the association between pelvic and nonpelvic size in females and males.

scholarly journals Architecture of the sperm whale forehead facilitates ramming combat

2015 ◽  
Author(s):  
Olga Panagiotopoulou ◽  
Panagiotis Spyridis ◽  
Hyab Mehari Abraha ◽  
David R Carrier ◽  
Todd C Pataky
Keyword(s):  
Connective Tissue ◽  
Stress Reduction ◽  
Structural Engineering ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Stress Concentrations ◽  
Moby Dick ◽  
Unique Structure ◽  
Complex Structural

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.

Social behavior and sexual dimorphism in the Bonaire whiptail, Cnemidophorus murinus (Squamata: Teiidae): the role of sexual selection

2003 ◽  
Vol 81 (11) ◽  
pp. 1781-1790 ◽  
Author(s):  
Troy A Baird ◽  
Laurie J Vitt ◽  
Teresa D Baird ◽  
William E Cooper, Jr. ◽  
Janalee P Caldwell ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Male Aggression ◽  
Body Dimensions ◽  
Light Blue ◽  
Ultimate Causation ◽  
Courtship Activity ◽  
Coloration Patterns

We measured body dimensions and coloration and quantified the behavior of females and males of two color phases in the Bonaire whiptail, Cnemidophorus murinus, to begin addressing the ultimate causation for sexual dimorphism in this species. Examination of size-adjusted body dimensions revealed that males have wider, longer, and deeper heads as well as somewhat longer forelegs and hind legs. Males were characterized by two distinct coloration patterns. Blue males displayed purple–blue dewlaps, blue–gray background coloration on the head and anterior torso, numerous light blue spots on the flanks, brown–orange coloration on the posterior torso, and a turquoise section on the proximal portion of the tail. By contrast, brown males were uniform olive–green to yellow–brown, with the exception of light blue spots on the lateral torso. Females were colored like brown males but lacked the blue spots. Testis length scaled with body size. Testes of only 26% of brown males were active, whereas all blue males had active testes. Blue males initiated aggressive encounters involving chases and displays directed toward other males much more frequently than females were aggressive with consexuals or with either type of male. Brown males were not observed to initiate aggression. Most blue male aggression was directed toward other blue males (70.6% of encounters), whereas 29.4% of encounters were with brown males. Blue males initiated 85.7% of the courtship encounters observed compared with only 7.1% initiated by brown males and 7.2% by females. Male-biased dimorphism in head and leg dimensions as well as coloration, together with higher rates of intrasexual aggression and courtship activity by blue males, are consistent with the hypothesis that sexual selection explains the evolution of sexual dimorphism in C. murinus.

scholarly journals Cetacean strandings along the Pacific and Caribbean coasts of Nicaragua from 2014 to 2021

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Joëlle De Weerdt ◽  
Eric Angel Ramos ◽  
Etienne Pouplard ◽  
Marc Kochzius ◽  
Phillip Clapham
Keyword(s):  
Marine Mammals ◽  
Sperm Whale ◽  
Distribution Patterns ◽  
Sperm Whales ◽  
The Pacific ◽  
Toothed Whale ◽  
Beaked Whales ◽  
Causes Of Mortality ◽  
Cuvier’S Beaked Whale ◽  
Stenella Attenuata

AbstractDocumenting marine mammal strandings provides important information needed to understand the occurrence and distribution patterns of species. Here, we report on strandings of cetaceans on the Pacific (n = 11) and Caribbean (n = 2) coasts of Nicaragua, documented opportunistically from 2014 to 2021. Strandings included three species of baleen whale (blue whale Balaenoptera musculus, Bryde’s whale Balaenoptera edeni, humpback whale Megaptera novaeangliae) and five species of toothed whale (dwarf sperm whale Kogia sima, Guiana dolphin Sotalia guianensis, pantropical spotted dolphin Stenella attenuata, spinner dolphin Stenella longirostris, Cuvier’s beaked whale Ziphius cavirostris). These are the first published accounts of blue whales, Bryde’s whales, dwarf sperm whales, and Cuvier’s beaked whales in Nicaraguan waters. Limited resources and the advanced decomposition of animals prevented necropsies in most cases, the identification of the causes of mortality in all cases, and the species identification of two dolphins. Information derived from these stranding events offers new insights into the occurrence of marine mammals on the Pacific and Caribbean coasts of Nicaragua and Central America.

scholarly journals Morphological determinants of jumping performance in the Iberian green frog

2019 ◽  
Vol 66 (4) ◽  
pp. 417-424
Author(s):  
Gregorio Moreno-Rueda ◽  
Abelardo Requena-Blanco ◽  
Francisco J Zamora-Camacho ◽  
Mar Comas ◽  
Guillem Pascual
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Fluctuating Asymmetry ◽  
Hind Limb ◽  
Limb Length ◽  
Age Classes ◽  
Jumping Performance ◽  
Hind Limbs ◽  
Selective Forces ◽  
Pelophylax Perezi

Abstract Predation is one of the main selective forces in nature, frequently selecting potential prey for developing escape strategies. Escape ability is typically influenced by several morphological parameters, such as morphology of the locomotor appendices, muscular capacity, body mass, or fluctuating asymmetry, and may differ between sexes and age classes. In this study, we tested the relationship among these variables and jumping performance in 712 Iberian green frogs Pelophylax perezi from an urban population. The results suggest that the main determinant of jumping capacity was body size (explaining 48% of variance). Larger frogs jumped farther, but jumping performance reached an asymptote for the largest frogs. Once controlled by structural body size, the heaviest frogs jumped shorter distances, suggesting a trade-off between fat storage and jumping performance. Relative hind limb length also determined a small but significant percentage of variance (2.4%) in jumping performance—that is, the longer the hind limbs, the greater the jumping capacity. Juveniles had relatively shorter and less muscular hind limbs than adults (for a given body size), and their jumping performance was poorer. In our study population, the hind limbs of the frogs were very symmetrical, and we found no effect of fluctuating asymmetry on jumping performance. Therefore, our study provides evidence that jumping performance in frogs is not only affected by body size, but also by body mass and hind limb length, and differ between age classes.

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