Male birds and fish tend to have brighter colors than females, which are usually dull brown, in order to attract mates. Some vertebrates like sea lampreys feed by boring holes in other animals and consuming their blood and tissues, rather than ingesting food. The bonobo and earliest known bird, Archaeopteryx, were vertebrates that shared characteristics with both birds and non-birds. Vertebrates range greatly in size, from the world's largest animal, the blue whale, to the smallest fish, only 8.4 mm in length.