Dive deep deep down into the ocean, long past the point where the sun’s rays can penetrate, and you will enter the realm of the ghost sharks. 
 
 Also called chimaeras, ghost sharks are dead-eyed, wing-finned fish rarely seen by people. 
 
 Relatives of sharks and rays, these deep-sea denizens split off from these other groups some 300 million years ago. Even though ghost sharks have been gliding through the depths since long before the dinosaurs, we still know very little about them. Now, video recently released by the Monterey Bay Aquarium Research Institute in California has shined new light on these mysterious creatures. 
 
 In 2009, the institute sent a remotely operated vehicle, or ROV, on several dives to depths of up to 6,700 feet in waters off California and Hawaii. They weren’t looking for ghost sharks: “The guys doing the video were actually geologists,” says Dave Ebert, program director for the Pacific Shark Research Center at Moss Landing Marine Laboratories. (See more amazing shark pictures.) 
 
 “Normally, people probably wouldn’t have been looking around in this area, so it’s a little bit of dumb luck,” he says. 
 
 One fish the ROV kept running into looked like a new ghost shark, since it did not resemble ghost shark species known to frequent either of these regions. 
 
 To find out its identity, the institute reached out to Ebert and other chimaera experts. The team analyzed the video and now believe it's a pointy-nosed blue chimaera (Hydrolagus trolli), a species usually found near Australia and New Zealand, according to a recent study in the journal Marine Biodiversity Records. 
 
 Though the ghost shark is not new to science, it's still exciting: The video is the first time the pointy-nosed blue chimaera has been seen alive in its natural habitat. 
 
 Uncovering Lost Sharks 
 
 If Ebert and colleagues are correct, the video is also the first discovery of this species in the Northern Hemisphere. 
 
 But they can't be sure unless they get DNA from an actual specimen, which is not easy. Ebert will scour local fish markets for new specimens, but one of the best—and only—ways is to use a trawling boat to scrape the depths. (The fish is usually dead by the time it makes it back up to the surface.) 
 
 Unexpected Shark Gives Explorer Shock of His Life A National Geographic researcher is startled to see a Greenland shark where none has ever been seen before: off Russia's Franz Josef Land. 
 
 Even without a physical specimen, the video has provided a wealth of information. First, unlike many creatures of the deep, pointy nosed blue chimaera seemed to be a ham for the ROV's camera and its bright lights. (See more pictures of odd deep-sea animals.) 
 
 “It’s almost a little comical,” says Ebert. “It would come up and bounce its nose off the lens and swim around and come back.” 
 
 In addition, rocky outcrops in the background of the video suggest that pointy-nosed blue chimaeras prefer this habitat to the flat, soft-bottom terrain that's usually the domain of other ghost shark species, says Ebert, a specialist in what he calls lost sharks, or species that don’t tend to garner the attention of great white sharks and hammerheads. 
 
 Unlike those more well-known sharks, chimaeras don’t have rows of ragged teeth, but instead munch up their prey—mollusks, worms, and other bottom-dwellers—with mineralized tooth plates. 
 
 A pattern of open channels on their heads and faces, called lateral line canals, contain sensory cells that sense movement in the water and help the ghost sharks locate lunch. 
 
 And perhaps most fascinating, male chimaeras sport retractable sex organs on their foreheads. (Also see "Two-Headed Sharks Keep Popping Up—No One Knows Why.") 
 
 "Water Bunnies" 
 
 At least three other species of chimaera likely live across the world's oceans, so it's not that surprising that the pointy-nosed blue would as well, says Dominique Didier, a marine biologist and chimaera expert at Millersville University in Pennsylvania. 
 
 “The only way we can collect these species is by trawling,” she says. “So, it's like a snapshot. Imagine trying to understand species distribution in Lake Michigan and you sample the lake using a Dixie cup. Trawling the ocean is like that.” 
 
 “I suspect many species are wide-ranging—we just don't have the data.” 
 
 Whether you call them chimaeras, ghost sharks, ratfish, or even “water bunnies”—which is what Hydrolagus roughly means in Greek—the fish “are just one of the many beautiful and poorly studied species that shares this planet with us," Didier says. 

 Currently there are 38 recognized species of short-nosed chimaeras (family Chimaeridae), making it the most species rich family in the order Chimaeriformes (Kemper et al. 2015). The family has two recognized genera that are separated by the presence (Chimaera) or absence (Hydrolagus) of an anal fin. The genus Hydrolagus is the more diverse of the two genera with 22 species (Didier et al., 2012). Fifteen of these species are recognized as occurring in the Pacific Ocean, but only five species are known in the eastern Pacific (James et al. 2009). These five Hydrolagus species are geographically dispersed around the Galapagos Island, the southeastern Pacific along the coasts of Chile and Peru, and lastly in the northeastern Pacific (James et al. 2009). Until recently Hydrolagus colliei (Lay and Bennett, 1839) and Hydrolagus melanophasma (James, Ebert, Long, and Didier, 2009) were the only species confirmed to occur in the northeastern Pacific. Hydrolagus colliei is found from Alaska to Costa Rica, while H. melanophasma occurs off southern California, USA to northern Chile (Angulo et al., 2014; Aguirre-Villaseñor et al. 2013). However, a third species of Hydrolagus, first noted but not identified by Ebert (2003), had been observed by remotely operated vehicle (ROV) at Davidson Seamount off central California at a depth greater than 2000 m. Lundsten et al. 2009 identify Hydrolagus trolli from the Davidson Seamount, however provide no descriptive information. Central North Pacific records of chimaeras are few, with only the purple chimaera, Hydrolagus purpurescens (Gilbert 1905), being reported from the Hawaiian Islands. 
 
 The pointy nosed blue chimaera, Hydrolagus trolli (Didier and Séret 2002), was described from 23 specimens. The holotype is a male specimen measuring 1030 mm (TL) that was captured by bottom trawl off New Caledonia (20°44.90’S, 167°43.10’E) at a bottom depth of 1246 m. Hydrolagus trolli is a little known chimaera species usually found at depths ranging 610–2000 m (Last and Stevens 2009). To date, this species has only been confirmed from the southwestern Pacific, off Australia, New Zealand, New Caledonia, the Lord Howe Rise and Norfolk Ridge (Last and Stevens 2009). This species, or a similar looking species, is known to occur over a much broader geographical range in the Southern Hemisphere, e.g. South Africa (Ebert and van Hees, 2015), but to date there are no descriptions of this species from the Northern Hemisphere. A specimen of H. cf. trolli was recorded off Chile (as H. pallidus in Andrade & Pequeño, 2006), (Bustamante et al. 2012). A potential specimen of H. trolli was collected off St. Paul Island in the Southern Indian Ocean but identification could not be confirmed due to poor condition (Didier and Séret 2002). 
 
 During a series of remotely operated vehicle (ROV) deep-sea surveys off the California coast and west of the Hawaiian Islands conducted by the Monterey Bay Aquarium Research Institute (MBARI), a large, bluish, short-nosed Hydrolagus species was observed on several occasions. Here we report on the occurrence of these Hydrolagus specimens that we have identified as Hydrolagus cf. trolli. 

 November 4, 2016 
 
 The deep sea is the largest contiguous habitat on the earth, covering two thirds of the earth’s surface and averaging over 3.5 kilometers deep. Because most deep-ocean waters are connected, many species of deep-sea animals have huge geographic ranges. For example, one deep-sea fish that was previously identified in the Southeastern Pacific has recently been found around the Hawaiian Islands and off the coast of Central California, according to a new paper by MBARI researcher Lonny Lundsten and his colleagues. 
 
 Scientists call this unusual fish Hydrolagus trolli, but its common name is the pointy-nosed blue chimaera. First named in 2002, it is known to live in deep waters around Australia, New Zealand, and New Caledonia. But until the recent paper, it had not been officially identified anywhere in the Northern Hemisphere. 
 
 Chimaeras are unusual fishes. Like sharks, their bodies are not stiffened by bones, but by plates and bone-like bits of cartilage. Like the chimaera from Greek mythology, which had a goat’s head, a serpent’s tail, and a lion’s body, chimaeras are pretty weird looking. Even the common names for this group—ghost sharks, rabbitfishes, and ratfishes—sound like creatures one might see at Halloween. However, chimaeras are relatively common and widespread in the deep sea, with 38 known species around the world. 
 
 In 2009, MBARI researchers worked with scientists at the California Academy of Sciences and Moss Landing Marine Laboratories (MLML) to identify a new species of ghost shark in the Gulf of California. Some of these same researchers had also seen ghost sharks during remotely operated vehicle (ROV) dives off Central California. They weren’t sure about the exact species, but they knew the fish did not look like either of the two species of ghost sharks previously identified from off the California coast. 
 
 In a recent paper in Marine Biodiversity Records, Lundsten and his colleagues presented evidence that the unidentified ghost shark they were seeing around Monterey Bay was, in fact the same species that had previously been identified only in the Southwestern Pacific. The paper cited three different chimaera experts who viewed the video from MBARI ROV dives and said that they believed the fish was a “pointy-nosed blue chimaera.” 
 
 In their paper, researchers refer to the fish as Hydrolagus cf. trolli. The letters cf. indicate that the researchers believe the physical characteristics of the fish they saw closely match the official species description for Hydrolagus trolli. Their alternative hypothesis is that the fish in MBARI’s videos are an entirely new species of ghost shark. 
 
 The researchers note that they can’t positively identify the ghost sharks in the ROV video without actually collecting one of them and bringing it back to the surface. This is much easier said than done, because these fish are generally too large, fast, and agile to be caught by MBARI’s ROVs. 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. This would allow them to either remove the cf. from their species description, or assign the fish to a new species altogether. 
 
 Similar looking, but as yet unidentified, ghost sharks have also been seen off the coasts of South America and Southern Africa, as well as in the Indian Ocean. 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. 
 
 Article by Kim Fulton-Bennett 
 
 Original journal article: 
 
 Reichert, A. N., Lundsten, L., & EBERT, D. A. (2016). First North Pacific records of the pointy nosed blue chimaera, Hydrolagus cf. trolli (Chondrichthyes: Chimaeriformes: Chimaeridae). Marine Biodiversity Records, 1–5. http://doi.org/10.1186/s41200-016-0095-5 
 
 Video about the newly expanded range for the pointy-nosed blue chimaera:
– Scientists using a remotely operated vehicle for geologic research instead spotted a g-g-ghost. National Geographic reports researchers recorded what is likely the first-ever video of a pointy-nosed blue chimaera in the wild more than 6,500 feet underwater off the coast of California. They published their findings in Marine Biodiversity Records. Chimaeras are better known as ghost sharks, "dead-eyed, wing-finned fish" that split off from other sharks and rays 300 million years ago and are rarely seen because of the ocean depths at which they live. (Interesting but unrelated: Male ghost sharks have retracting sex organs on their foreheads.) The program director for Pacific Shark Research Center says it was "a little bit of dumb luck" researchers got the footage of the ghost shark, which unlike other deep-water creatures appeared to actually like the remotely operated vehicle and its lights. Researchers at first believed the ghost shark was a new species before it was identified as likely a pointy-nosed blue chimaera. That particular species has only ever been seen near Australia and New Zealand, though MBARI notes most deep-water species have surprisingly wide-ranging habitats. It's still possible the ghost shark caught on video is a new species, but scientists won't know for sure until they catch one. (Some of these sharks may be older than the US.)