Any scientist will tell you that dimorphism is extremely important. That's really cool to know, isn't it? Well, it would be... if only you knew what sexual dimorphism was.
Sexual dimorphism is the visible difference between the male and female of a certain species. Humans are a classic example - men look so different from women that they're easily distinguishable at first glance.
In many other species of the animal kingdom, there are huge differences in the appearance of the male and the female, too. These differences serve a lot of purposes; whether it's for protection from predators or helps with attracting a mate, males and females of some species need to stand out from the others.
SEXUAL DIMORPHISM IN THEORY
In some species, the male is the one with all the bright colors, the scary-sounding shriek, and big claws. Other species have dominant females who need to look a certain way to protect herself and her babies from predators. These are both examples of what's known to scientists as sexual dimorphism - in basic terms, this simply means that the males and females of a species look different from one another.
SEXUAL DIMORPHISM IN ACTION
When a male peacock struts his stuff, it's an inspiring show for the girls. He looks as if he can scare off predators, and that blue and green pattern is so in right now - he certainly knows how to dress. A female peacock will be more attracted to a male with an impressive display than one without, because he can protect her and their babies if she pairs up with him. Besides, he's cute!
Sometimes the female of a species is the bodyguard for her family. When that's the case, she'll often be bigger than her male counterpart, and may wear bright, commanding colors to scare predators away. The female Black Widow spider is usually twice the size of the average male - she needs to be, because she's responsible for laying eggs and finding a suitable home for them. And contrary to popular belief, she rarely eats her mate; she just sends him packing once her eggs have been fertilized.
Sexual dimorphism is extremely important in the animal kingdom, both for protection against predators looking for a fast-food dinner and for reproductive purposes. Without the important differences between males and females, it would be impossible to distinguish what's most significant to each creature.