Ancient Eighty-million-year-old Shark Variety Remains Biological Enigma
In the depths of the ocean, where light is scarce and pressure is immense, resides a creature that has long intrigued scientists - the frilled shark. This unusual-looking shark, with its lacy collar of gill slits and trident-like teeth, has been slithering its snake-like body through the dark depths for tens of millions of years.
Frilled sharks are known for their distinctive features. Their first pair of gill slits connect together under their throats, resembling lacy collars, while inside the mouth, rows of three-pointed teeth, reminiscent of miniature tridents, await their prey. These sharks also have six large gill slits, one more than most sharks, and a 2m-long (6.5ft) brown or grey body with a dorsal fin near the trailing, ribbon-like tail.
When it comes to reproduction, frilled sharks are unique. Unlike many other sharks, they give birth to live young, typically bearing 4 to 6 pups every 2 to 3 years. However, their gestation period is exceptionally long, estimated at up to 42 months (3.5 years), possibly the longest of any shark species. This slow reproductive cycle and shorter lifespan, estimated at about 25 years, contribute to their vulnerability to environmental changes and fishing pressures.
Frilled sharks primarily feed on soft-bodied squid, smaller sharks, and bony fish. They exhibit diel vertical migration, meaning they move toward the surface at night to feed, likely taking advantage of prey availability during this time. In contrast, great white sharks, with a longer lifespan of 40 to 70 years, feed on seals, fish, and other ocean life and have a different hunting style, relying on powerful biting adapted for tearing flesh.
Comparatively, coelacanths, another deep-sea species sometimes compared in reproductive biology, have a gestation of about 5 years, while great white sharks have a shorter gestation (around 1 year) and produce 2 to 12 pups per litter.
In summary, frilled sharks share the characteristic slow reproduction common to many deep-sea species, which contributes to their vulnerability. For more mind-blowing science facts, check out our ultimate fun facts page.
Recent discoveries and rare footage have shed more light on these elusive creatures. In 2022, a viral video showed living frilled shark footage in Japan. Despite their ancient origins, dating back to the Late Cretaceous period, around 80 million years ago, frilled shark descendants are still present in the deep sea.
However, misconceptions about frilled sharks persist. News outlets had to clarify that the frilled shark is not an 80-million-year-old prehistoric shark. Instead, it is a fascinating and enigmatic deep-sea creature known as Chlamydoselachus anguineus.
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- The distinctive gill slits and trident-like teeth of frilled sharks, a deep-sea creature, make them a fascinating subject of study in both science and nature.
- As deep-sea dwellers, frilled sharks have a slow reproductive cycle, making them vulnerable to medical-conditions and technology-related changes in their environment, such as fishing pressures and climate change.
- Though sharing some reproductive traits with coelacanths, another deep-sea species, frilled sharks are not prehistoric, contrary to popular misconceptions; they are actually a type of shark scientifically known as Chlamydoselachus anguineus.
