00:00During a series of remotely operated vehicle surveys off California and Hawaii,
00:05six observations of a large, deep-sea chimera, identified as Hydrolagus troli, were documented.
00:13These records are the only images of this rare species in its natural habitat
00:19and reveal a significant range extension into the northern hemisphere.
00:23This species was named in honor of Alaskan artist Ray Troll,
00:27whose fascination and appreciation for this weird group of fish has inspired some of his artwork.
00:33Chimera skeletons are composed of cartilage, not bone,
00:37a characteristic that groups them together with sharks and rays.
00:40They are sometimes known, informally, as ratfish or ghost sharks.
00:45But unlike sharks, with their conveyor belt rows of teeth,
00:49chimeras have non-replaceable tooth plates,
00:52composed of dense minerals and an upper jaw that is fused to their skull.
00:57Chimera species are described using a combination of physical features,
01:02including coloration, lateral line canal pattern, fin shape, eye size, and snout shape.
01:10It can be difficult to distinguish between species due to subtle differences in these characteristics.
01:16Hydrolagus troli, the pointy-nosed blue chimera,
01:20was first described in 2002 from 23 specimens captured off New Caledonia
01:25at depths from 610 to 2,000 meters.
01:30This species had only been identified by specimens caught in the southwestern Pacific
01:35off Australia, New Zealand, and New Caledonia,
01:39until the Monterey Bay Aquarium Research Institute filmed them off the west coast of Hawaii,
01:44San Juan and Davidson Seamounts, and Monterey Canyon off California.
01:49These video observations show individuals occurring over rocky seafloor,
01:53suggesting that this species may prefer this habitat.
01:57This was unexpected because ghost sharks are usually found over sedimented seafloor.
02:02We refer to these video observations as Hydrolagus CF troli.
02:06The CF translates to compare with,
02:09indicating that these six observed specimens most closely resemble the species Hydrolagus troli.
02:16In order to confirm the identity of this animal,
02:19we need to collect specimens, analyze its physical characteristics,
02:22and conduct DNA analyses so we can compare it with other known species.
02:28These likely observations of Hydrolagus troli increase the number of known Hydrolagus species
02:34to three off California, and two off the Hawaiian Islands.
02:38If further analysis were to reveal that these fishes are not Hydrolagus troli,
02:43they most likely represent a new species.
02:46This is yet another example of how little we know about the deep sea,
02:50where opportunities for exploration and discovery still await.
02:53Are you sure you want to take a look at it today?
02:54Yes!
02:54Grazie a tutti.
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