When THAT Exception Persists Almost as THAT Exception

We present the counterpart to Chap. 4 in Chap. 5 , where we focus on the role of “permanent” exceptions and their importance in scientific knowledge and biology. These exceptions can be analyzed at any scale and are often not appreciated beyond anecdotal mentions. They can be aberrant or teratological groups, taxonomic groups unique for some features of their biology, “intermediate exceptions” with minorities of species or clades with certain characteristics compared to the majority, or organisms with exceptional distributions in space or time. In this chapter, we reviewed groups that have been difficult to classify because of their rarity, rarities that can be used for human benefit, exceptional groups that make us rethink phylogenetic relationships, rare and incredible biological phenomena, and evolutionary and ecological aspects of rare species. Our goal is to vindicate rarities and minorities, to highlight their importance for the understanding of evolution, and to begin to make these cases visible and treasured in the teaching of biology.