Face-Down, Tail-Up: Unusual In Situ Behavior of the Blackchins Neoscopelus macrolepidotus, Neoscopelus microchir, and Scopelengys tristis (Myctophiformes: Neoscopelidae)

Abstract

Orienting vertically with the head facing upward allows fish to look for the shadow of their prey against ambient light, while also making their own shadow smaller to predators beneath them. Here, we describe the in situ behavior of three midwater fish in the family Neoscopelidae, Neoscopelus macrolepidotus, Neoscopelus microchir, and Scopelengys tristis, all of which were observed facing vertically with the head downward. This behavior allows the fish to diminish its shadow to hide from predators while hunting prey below. Assessing unique behaviors helps us better understand the role of these and other poorly studied deep-sea fishes.