Deepsea Loosejaw

Photostomias guernei are distributed worldwide. P. guernei has been reported in the Atlantic and Pacific oceans in temperate and subtropical waters. Following the life history of P. guernei, distribution is concentrated in the western and eastern Atlantic and the southeast Pacific. P. guernei is estimated to be the most abundant Stomiid of the eastern Gulf of Mexico.

Habitat. Photostomias guernei is a marine fish that occupies the bathypelagic zone, keeping within 1138 and 3100 meters of depth. It is classified as maintaining an asynchronous pattern of diel vertical migration, occupying different ranges within the water column at different times of the day. During the daytime, P. guernei occupies the lower regions of the mesopelagic zone. Caught specimens reveal that larger members of the P. guernei species occupy greater depths during the daytime. At night, trends show P. guernei residing in various locations, notably within clusters in the epipelagic and the mesopelagic.

Photostomias guernei is a hunting predator that ambushes prey with its improved sight. P. guernei primarily utilizes visual cues to find prey. Once suitable prey is within reaching distance, the rotating jaw will extend forwards to trap the prey. The gaping mouth and the distensible stomach of P. guernei allows it to consume large prey. The basibranchial teeth near the gill arches assist in keeping prey from escaping.

The name of the genera Photostomias is derived from Greek photos (light) and stoma (mouth). The eponymy of guernei follows French zoologist and geographer Jules Germain Maloteau de Guerne.