Ever wonder why males and females of the same species can sometimes look radically different from each other? It's all thanks to a condition known as sexual dimorphism, which is generally triggered by the process of sexual selection through competitive mating. Sexual dimorphism can manifest in many fascinating ways — size, coloration, behavior and the presence of secondary sex characteristics liketail feathers, breasts or antlers.
其中的最好的例子是山魈，这被广泛认为是最有性别二态性哺乳类动物。当您检查雌雄山魈以上，你会的第一件事的图像注意到的是，男性表现出对他们的脸和屁股更具活力的色彩。但是，如果你遇到one of these majestic primatesup-close, you'd quickly realize that the most dramatic difference between their sexes is their size. While the average female mandrill weighs about 27 pounds, some male mandrills can weigh up to 82 pounds!
Mandrills have nothing on the triplewart seadevil, though. Living as deep as 6,600 feet below the ocean's surface, these令人毛骨悚然的前瞻性琵琶鱼可以说是世界上最极端的两性异形的彻头彻尾的怪异表现。如下面的图中显示出，该物种的雌性测量关于长的脚，而男性勉强达到半英寸。
This dramatic disparity in size is largely due to the species' parasitic mating practices. (That's right, it's love at first bite!)
由于MNN的布赖恩·纳尔逊explains, "The evolution of the male anglerfish has left them highly reduced. In some species, the males are not even capable of feeding themselves. Instead, they must quickly find a female to attach themselves to, or die. After attaching, their circulatory systems merge and she provides him with sustenance, while he provides her with sperm."
Continue below to learn about more animals that exhibit striking instances of sexual dimorphism.
These pinnipeds are named for the males' large proboscises that slightly resemble an elephant's trunk. The reason they've developed this bulbous schnoz has less to do with their appearance and more to do with proboscis' ability to emit incredibly loud roars during mating season.
Orange tip butterflies
The iconic bushy manes of African lions are highly linked to the process of sexual selection, and studies have shown that lionesses are more likely to pick a mate that boasts a dark, thick mane.
而两性的鸳鸯拥有博tiful plumage, the males of this species are especially striking with their red bills, pronounced crests and array of colorful feathers.
As they reach sexual maturity, male orangutans begin to develop enlarged cheek flaps that are meant to exhibit their dominance. When there is more than one male within a family, the more dominant male will exhibit more exaggerated cheek flaps.
Peafowl are among the most well-known and gorgeous examples of sexual dimorphism. While males (peacocks) sport a flamboyant and iridescent "train" of tail feathers that can open up in a grand display, females (peahens) possess a significantly more subdued appearance.