Copepoda. In Schmidt-Rhaesa. "Guide Identification of Meiofauna"

Because of their size, their diversity, and their abundance, Copepoda have been regarded as “insects of the sea” (e. g. Huys & Boxshall 1991). However, as argued by Schminke (2007), the contrary was more appropriate: insects should be seen as “the terrestrial copepods”, due to the fact that copepods had to face much more impediments in their evolutionary history than the latter but notwithstanding reached the recent quite successful position within the aquatic realm. It is not possible to give an exact number of marine Copepoda, as a huge amount of species is still undescribed. The latest estimation revealed around 11 290 accepted marine species (Costello & Chaudhary 2017), including about 6500 marine benthic Copepoda (Table 27.1; Walter & Boxshall 2018a-f). The number of totally expected copepod species varies remarkably; while Humes (1994) estimated ~75 000 and Appeltans et al. (2012) attain to 50 125, Seifried (2004) speculates about even ~450 000 copepod species