A fishing trawler, working to minimize unwanted bycatch and the impact of commercial fishing on untargeted species off the coast of Portugal, has caught a rare sample of a primitive shark that's often referred to as a living fossil. The frill shark isn't literally unknown, but it's uncommon to catch them. It's called a living fossil (a term also sometimes used to refer to species like the coelacanth, glypheoid lobsters, and the dawn redwood). The term refers to a species that was previously known from the fossil record, but is then discovered alive in the modern world. In the frill shark's case, it dates back to 80 million years ago.
The frill shark is distinctly different from other shark species that still exist today. While great white sharks appear in the fossil record as early as 66 million years ago, the frill shark looks more like a type of eel, albeit a finned eel with a great many multi-pointed teeth. It has a notochord rather than a cartilaginous spinal column.
The name of the shark appears open to debate. Multiple sources attest that the frill shark is called such because the arrangement of gills around its throat looks like a frilly collar. Such collars were more in-fashion in the past than today and the shark was first described by a German researcher in the late 1800s. The BBC, however, reports that the shark's name is because its teeth resemble a frill(Opens in a new window). If you can settle this debate for us one way or the other, sound off below.
The frill shark is considered to be a potential inspiration for mythical tales of sea serpents, though its relatively short length (6.6 feet) make it a poor candidate for the ship-crushing serpents of various myths. Then again, we're talking about groups of people who saw a creature we now nickname the "sea cow" and thought they'd actually seen beautiful mermaids luring sailors to their deaths.
Frill sharks have been caught around the world, but only rarely observed by humans. It's been reported around the world but never in large numbers, typically at depths above 3,300 feet (the 2,300-foot depth of this catch is within the normal range). It's an example of how poorly we understand the distribution and ecosystem role of many ocean-dwelling creatures -- we've barely scratched the surface of the underwater biosphere, in many cases, due to the intrinsic difficulty of taking underwater surveys or extensive studies over long periods of time.
The finned shark is not believe to be in any danger from fishing or harvesting and is classified as Least Concern by the IUCN.
Top image credit: SIC Noticas
