The elusive “ghost shark”, also known as the pointy-nosed blue ratfish, had recently made its video début as footage caught by the ROV (remotely operated underwater vehicle) Tiburon, operated by MBARI (the Monterey Bay Aquarium Research Institute) was published alongside a new study in the journal Marine Biodiversity Records.
“It’s a bizarre-looking fish with a pointed snout,” said Lonny Lundsten, a senior research technician at MBARI in California. “It has a long, pointed, tapering tail, relatively large eyes, [and] it’s almost entirely greyish-blue.”
The videos, six in all, originally taken between 2000 and 2007, provide the first evidence that this species of ratfish lives in the Northern Hemisphere.
Dominique Didier, Professor of Biology at Millersville University in Pennsylvania, who named the species in 2002 (after the first three videos had already been taken) in a paper published in the journal Cybium, where it was officially named Hydrolagus trolli, in honour of the Alaskan science illustrator Ray Troll, had never even seen it with her own eyes.
Instead, the discovery was made by studying 23 dead H. trolli specimens captured as by-catch by trawlers (deep sea fishing boats that catch marine animals with large nets) in the south-western Pacific Ocean.
After seeing the MBARI videos, Didier confirmed that the deep sea creature, which looks stitched-together not unlike Frankenstein’s monster, is likely “ghost fish”.
The videos are helping scientists understand more about this mysterious species of fish, which lives 1.6 to 2 metres under the surface and measure between 0.6 and 0.9 metres long.
One finding has to do with habitat: “[Ratfishes] are typically found above soft sediment, and the fact that these live in a rocky habitat is unique to this group.”
Lundsten also explained that the strange stitch-like lines on the bodies of H. trolli are actually sensory organs that cover the fish’s entire body, helping it sense minute movements and vibrations in surrounding water, which helps it hunt prey.
In addition, male ratfish “have a strange sexual-related organ that’s on the top of their head,” Lundsten said. “It’s a club-shaped thing that has spines on it, and it’s used for grasping and better positioning the female during copulation.”
Just like their relatives, such as rays and sharks, ratfishes have skeletons made of cartillage, and date as far back as 350 to 370 million years, indicating they have been around well before the dinosaur age.