Odd Couples: Extraordinary Differences between the Sexes in the Animal Kingdom
Daphne J. Fairbairn
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While we joke that men are from Mars and women are from Venus, our gender differences can't compare to those of many other animals. For instance, the male garden spider spontaneously dies after mating with a female more than fifty times his size. And male blanket octopuses employ a copulatory arm longer than their own bodies to mate with females that outweigh them by four orders of magnitude. Why do these gender gulfs exist?
Introducing readers to important discoveries in animal behavior and evolution, Odd Couples explores some of the most extraordinary sexual differences in the animal world. Daphne Fairbairn uncovers the unique and bizarre characteristics of these remarkable species and the special strategies they use to maximize reproductive success. Fairbairn also considers humans and explains that although we are keenly aware of our own sexual differences, they are unexceptional within the vast animal world.
Looking at some of the most amazing creatures on the planet, Odd Couples sheds astonishing light on what it means to be male or female in the animal kingdom.
Times longer than males (figure 6.1).5 Because of the massive size of the female abdomens, especially when full of eggs, the mass differential between sexes is much greater than these length differences would suggest: mature females can weigh as much as 1.5 g (0.05 oz), whereas males seldom exceed 20 mg (0.02 g), and at the height of the breeding season females weigh an average of fifty-three times more than males (table 6.1). Although certainly impressive, A. aurantia is neither the largest nor.
They cannot mate again whether they survive or not. Thus, strange as it may seem from a human perspective, the male spiders have nothing to gain by further survival, and so their death on second insertion in no way reduces their Darwinian fitness. The life of a male yellow garden spider is clearly fraught with daunting challenges. If he hopes to father any spiderlings he will have to contend with rival males, cannibalistic females (literally “femmes fatales”), or both, and his personal reward.
Animals, but not to us. Nevertheless, they are clearly not as pervasive as dimorphisms in size, shape, appendages, or primary sexual traits. That concludes my survey of the typical patterns of sexual dimorphism for various categories of sexually dimorphic traits, so it is time to step back and look once again at the overall picture across the animal kingdom. The main conclusion that emerges is that the division of reproductive function between males and females is almost always associated with.
Providing the wonderful photographs that illustrate chapter 3, he has been a sounding board and a source of encouragement throughout the project, and I am deeply grateful, as always, to have him by my side. APPENDIX A Scientific Names Corresponding to Common Names Used in the Text Common name Scientific name Acorn barnacles Crustacean arthropods in the class Maxillopoda, subclass Cirripedia and order Sessilia Anglerfishes Fish in the teleost order Lophiiformes Arrow worms.
Brown songlark Cincloramphus cruralis Burrowing barnacles Crustacean arthropods in the class Maxillopoda, subclass Cirripedia, and superorder Acrothoracica Cassowaries Large flightless birds (ratites) in the genus Casuarius Chimeras Marine fishes with cartillaginous skeletons in the Chordate class Holocephali Cichlid fishes Bony fishes in the Class Actinopterygii, order Perciformes, and family Cichlidae Cobweb spiders Spiders in the family Theridiidae; includes black widow.