Deep-sea creatures are infamously mysterious and bizarre-looking, so they tend to cause a bit of a stir when they show up on the surface. And that's exactly what happened when a dead ragfish washed up near a dock in the Alaskan city of Gustavus earlier this week. 

Reports say the six-foot (1.8 metre) animal was initially mistaken for a halibut when it was spotted by a local transportation worker – but a closer look revealed a strange fish he'd never seen before. And that's not surprising since the species is very rarely seen. In fact, it's rare and enigmatic enough to have earned a scientific name to match: Icosteus aenigmaticus.

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. 

This week's find comes hot on the heels of another ragfish appearance in the Glacier Bay area just last year, when a two-metre specimen washed up in a nearby cove.

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Another large ragfish washed ashore in the area back in July last year. Image: Glacier Bay National Park and Preserve/Facebook

While examinations of both fish found their stomachs to be empty, they did uncover something else: both were females that were carrying eggs, says the park in a Facebook update.

One ragfish sighting alone is a pretty unusual thing, so seeing two washed-up specimens in the same area in the space of just a few months is bound to spark some questions, state fisheries biologist Craig Murdoch tells Alaska Dispatch News. 

According to one local naturalist and long-time Gustavus resident, these are the only reported observations of these fish in the area in the past 40 years. But given how little we know about this elusive species, it's hard to tell what the significance of the sightings might be, Murdoch adds.