Darkest animals

The darkest animals currently known to science are deepsea anglerfishes belonging to the genus Oneirodes. In September 2020, a study of ultra-black deepsea fishes published in the journal Current Biology revealed that these particular anglerfishes exhibit a reflectance as low as 0.044% at 480 nanometres (nm), with a 0.051% average reflectance from 350–700 nm. Put another way, their skin absorbs as much as 99.95% of all light hitting it. Sunlight does not penetrate the depths of sea where they live, but there are bioluminescent creatures, whose light could hit and therefore illuminate the anglerfishes, betraying their presence to potential prey animals. Consequently, in order to camouflage themselves effectively and thus remain concealed from prey, these anglerfishes' skin possesses such closely packed layers of melanosomes containing black pigment (melanin) that they scarcely reflect any external light at all, thereby rendering themselves virtually invisible. Their skin colour is thus termed "ultra-black".

Prior to this discovery, the blackest-known animals were various predominantly black-plumed bird-of-paradise species from New Guinea, whose velvety ultra-black feathers exhibit 0.05–0.31% reflectance. There are also a number of ultra-black butterflies, whose wing scales exhibit 0.06–0.5% reflectance. In these animal types, it is hypothesized that the ultra-black feathers and scales serve to enhance the perceived brilliance of adjacent colour patches during courtship displays.