Its other nicknames — ratfish, rabbitfish, spookfish — hint at how bizarre chimaeras are in appearance.
And now, scientists believe they have captured on video a species of ghost shark that had never before been filmed live: the pointy-nosed blue chimaera.
The actual video was taken in 2009 but was only recently released by the Monterey Bay Aquarium Research Institute, along with a paper by researcher Lonny Lundsten and his colleagues at the institute.
Six years ago, researchers from the nonprofit sent an ROV, or remotely operated vehicle, on several dives off the waters of central California and Hawaii.
The ROVs captured footage from depths of up to 6,700 feet. What they returned with surprised researchers: On film was what appeared to be a species of ghost shark previously only caught in the southwestern Pacific Ocean.
According to his paper, Lundsten consulted with three chimaera experts who watched the video from the diving expeditions. All believed the fish was, in fact, a pointy-nosed blue chimaera.
Still, Lundsten and others from the Monterey Bay Aquarium institute can't be 100 percent certain that the fish captured on video is a pointy-nosed blue chimaera, despite their similar physical characteristics. Because of that, the paper refers to the fish they recorded as Hydrolagus cf. trolli, rather than its scientific name, Hydrolagus trolli.
To be absolutely sure, researchers would have to capture the ghost shark and bring it back to the surface, the institute said.
“This is much easier said than done, because these fish are generally too large, fast, and agile to be caught,” the institute notes. “If and when the researchers can get their hands on one of these fish, they will be able to make detailed measurements of its fins and other body parts and perform DNA analysis on its tissue.”
Doing so would either allow them to remove the “cf.” from the species description — or lead to perhaps an even more exciting alternative: that they discovered a new species of ghost shark.
“If these animals turn out to be the same species as the ghost sharks recently identified off California, it will be further evidence that, like many deep-sea animals, the pointy-nosed blue chimaera can really get around,” the institute said.
The pointy-nosed blue chimaera was first discovered by researcher Dominique Didier Dagit in 2002, in the deep waters around Australia, New Zealand and New Caledonia.
Dagit, then an assistant curator of ichthyology at the Academy of Natural Sciences in Philadelphia, told the Associated Press in 2002 that she named her discovery Hydrolagus trolli after Alaskan artist Ray Troll because they shared a love for ratfish.
''It's kind of nice to be able to name a species for someone,'' Dagit told the AP. ''I thought, 'Here's my chance to name a fish for someone who's really interested.' . . . It kind of looks like him, [but with] less facial hair.''