Angel Shark
Until fairly recently, scientists attempting to establish the existence, health, or migration of marine life had to use nets, cameras, or other means to identify and count the number of animals involved. Now researchers have a new and powerful tool, environmental DNA, or eDNA, a revolutionary technology that is helping scientists detect in real time the genetic information that animals leave in their wake.
Scientists have refined ways of extracting strands of genetic material from salt water, soil, and air. Depending on conditions, DNA can last for days in the ocean after an animal has shed it. Using small water samples collected at differing depths researchers can track where a specific species has swum, by checking DNA samples against reference databases.
eDNA Search for the Angel Shark
This week an article in the Washington Post highlights the use of eDNA in the search for angel sharks, one of the world’s most elusive sharks, in the waters off Corsica. As the Post notes, “The angel shark does not want to be found.
“With a flattened body and eyes on top of its head, the common angel shark, or Squatina squatina, lies on the bottom of the ocean, burying its body in the sand. For hours it waits in shallow waters until — whoosh! — it pops its head up, opens its jaws, and sucks an unsuspecting fish into its mouth.”
The angel shark was once numerous and widespread but fell prey to modern fishing trawls. Slow to grow and reproduce, the fish’s population plummeted and the Mediterranean lost a key predator. Today, the common angel shark is no longer common, with the International Union for Conservation of Nature listing the species as critically endangered.
By 2015, its last stronghold appeared to be the Canary Islands off northwestern Africa. Nevertheless, locals in Corsica reported signs of the elusive fish until a series of photographs taken by divers in 2019 proved the point.
Now researchers have used eDNA to find at least seven spots along the Corsican coast where angel sharks were still patrolling, according to a paper the team published in May. But more may be lurking undetected, the Washington Post notes.
Searching for Nessie and Finding Eels with eDNA
In 2019, eDNA was used to search for “Nessie,” the mythical monster of Loch Ness. Sadly for “Nessie” aficionados, a scientific survey of the waters of Loch Ness found it contained no traces of “monster” DNA at all, adding weight to the prospect that “Nessie” doesn’t really exist.
Geneticist Neil Gemmell of Otago University in New Zealand, who led the survey, said “we did not find any giant reptiles; we didn’t find any reptiles at all,” Gemmell told Live Science. “We tested a variety of ideas about giant sturgeons or catfish that might be here from time to time, but we did not find those either.”
One thing the researchers did find is that Loch Ness contains a lot of eels. And the researchers say it is possible, although unlikely, that sightings of Nessie may actually be sightings of overgrown eels.
He admits that he was skeptical about the existence of the Loch Ness monster even before the survey was carried out, but said the result left a very slim chance that it could still be real.
Recent studies, however, confirm that if Nessie is indeed real, it isn’t likely a giant eel.