the elephant seals enter the "twilight zone" -- also known as the mesopelagic zone -- a layer of the ocean that extends from about 656 feet to 3,280 feet below the ocean's surface that is abundant ...

By Spoorthy Raman Rhythmic clicks, grunts and roars fill the Año Nuevo Island Reserve in California, home to a large breeding ...

To estimate the biomass of fish in the twilight zone – the area of ocean at 200-1000m below sea level – scientists used acoustic instruments called echo-sounders.