[2] A total of 16 out of the 18 species caught in these trawls were found to have skin that reflected less than 0.5% of the light that hit it and that could thus be termed ultra-black.
[2][3] This ultra-black skin may serve several purposes depending on the biology, preferred food sources, and predators of each species.
While most of these species likely use this coloration as camouflage to hide from predators, some of them, including fish that attract prey using bioluminescent lures like Astronesthes micropogon and Oneirodes sp., could potentially use ultra-black skin to catch prey unawares and prevent them from being seen in the light from their own lures.
[2] What makes these fishes unique from other animals that have ultra-black coloration, like butterflies and birds-of-paradise, is that those animals have structures that capture light and direct it into the melanin in their skin, while the fishes do not have those structures and rely solely on the pigment in their melanosomes to absorb incoming light.
[4][5] Being able to reproduce the mechanism these fishes use to absorb light has industrial applications because the ultra-black products humans make use carbon nanotubes, which are very delicate, to trap light and being able to replace these nanotubes with a pigment-based system would improve the durability of current products and open the door for new applications.