Kingdom Animalia, phylum Cnidaria (corals, medusae, anemones, hydroids, staurozoans, & myxozoans).

The total number of described, and known but undescribed, extant marine cnidarian species, from the Aotearoa New Zealand region, is 1420 (Table 6.1; Figs 6.1–6.3). In their first major inventory of the cnidarian fauna of New Zealand, Cairns et al. (2009) recorded 1112 marine species, of which 323 were undescribed or unidentified. Over the last decade there has been a considerable increase in our overall knowledge of cnidarian diversity for New Zealand waters. Described cnidarian species have increased to 1020 and undescribed cnidarians to 400 species. The discovery rate and rate of description of new taxa has increased primarily due to significant new taxa descriptions for black corals (Antipatharia) and primnoids (Scleralcyonacea; Primnoidae). The inventory of New Zealand Cnidaria has been updated here and a checklist of extant taxa is included. No updates have been made to the checklist of fossil Cnidaria of New Zealand except for the addition of Bensonularia spatulata (Hamilton 1958).