dimorphic

Dimorphism varies greatly in the animal kingdom. Among mammals, the male is generally larger than the female, but other differences in appearance tend to be modest. But birds are usually noticeably dimorphic, with the male being the more colorful sex; when we imagine a pheasant, a mallard, a cardinal, or a peacock, we're almost always picturing the male rather than the female. Among spiders the situation is often reversed. The golden orb-weaver spider, for example, is spectacularly dimorphic: the female may be 20 times the size of the male, and she usually ends up eating him, sometimes even while he's mating with her. Many sea creatures, including many fish, take care of gender problems by simply changing from one sex into the other.