So what do we know about it? Adults cruise across the North Pacific at depths of around 4,000 feet (over 1,200 metres), hunting squid, small fish, octopus and jellyfish. Ragfish in turn fall prey to another deep-sea denizen ... but a much bigger one: their remains have been found inside the stomachs of the world's largest toothed predators, the sperm whales.

"The [ragfish] species undergoes a bizarre transformation as it ages: it loses its pelvic fin and the dorsal fin shrinks. Juveniles have be found from the surface to more than 2,400 feet while adults have been caught as deep as 4,660 feet," explains the team at Glacier Bay National Park and Preserve, which has its headquarters in Gustavus.