In the vast and mysterious oceanic depths, a creature lurks, shrouded in mystery and wonder – the frilled shark. With a lineage that dates back to the depths of prehistoric times, this enigmatic creature continues to captivate marine enthusiasts and researchers alike. Join us as we delve into the depths of the ocean to reveal the hidden facts and untold tales of this living fossil.
1. They look like snakes
The frilled shark, also known as the scaffold shark, fringe shark, silk shark, or lizard shark, is a fascinating deep-sea creature that has remained relatively unchanged for thousands of years, earning it the title of a living fossil. This species has been around for more than 80 million years. The family Chlamydoselachidae comprises only two living shark species: this particular species and the southern African frilled shark (Chlamydoselachus africana).
These sharks are among the weirdest sea creatures in the world. They have a slender, eel-like appearance with a long, smooth body that is capable of flexing and bending. Resembling serpents beneath the waves, they propel themselves through the water using the strength of their tail.
The frilled sharks possess compact, circular pectoral fins, a diminutive dorsal fin, and expansive, broad anal and pelvic fins situated at the tail end of their bodies. Their caudal fin is substantial, forming a large, triangular shape and adorned with scales. Along their bodies, there is a lateral line, which supports their perception and allows them to sense alterations in their surroundings and detect electrical pulses produced by animal muscles.
Besides the movements, these sharks also have a snake-like face. They come with notable characteristics such as large deep-set eyes, vertical slits serving as noses, and blunt snouts culminating in jaws. Their most remarkable attribute lies in their collection of over 300 teeth, which resemble thin, spiky structures angled backward, akin to miniature tridents. The upper jaw contains about 19-28 rows of teeth, while the lower jaw has 21-29 rows.
Unlike most deep-water sharks, this eel shark stands out with an extraordinary trait. Instead of the typical five gills near its throat, it possesses an additional sixth gill. The first gill connects at the front of its throat, forming a distinctive collar, while the remaining five form a fleshy frill. This exceptional characteristic is what gives these sharks their name.
The frilled neck shark boasts a rich, chocolate-brown hue, with a slightly lighter shade on their ventral sides. These sharks often have a size of about 5,5 – 6,5 feet in length, with males being smaller than females. They weigh about 200-300 pounds (91-136 kg).
Discovered in the 19th century by German ichthyologist Ludwig H.P. Döderlein, the frilled shark continues to fascinate both scientists and enthusiasts to this day. With their ancient and prehistoric features and the absence of close relatives, these ancient creatures stand out as exceptionally extraordinary and unparalleled species.
2. Frilled shark Habitat
The distribution of the frilled shark is not extensively documented, but it can be found in different seas worldwide. Various regions in the Pacific Ocean have witnessed their presence, spanning Australia, southeast Japan, southern California, New Zealand, and Taiwan. Similarly, in the Atlantic Ocean, they have been documented in Norway, western Ireland, northern Scotland, Namibia, and Chile.
Although they live everywhere in the world, their distribution is somewhat irregular, with populations scattered across the oceans.
The sharks commonly inhabit the deep sea, usually ranging from depths of 100 to 1,000 feet. However, they are capable of going down even deeper, reaching depths of 4,900 feet or beyond. On rare occasions, have been discovered as far as 5,100 feet below the ocean’s surface.
Squids are frilled sharks’ favorite food. These cephalopods account for approximately 60% of their diet. Teleost fishes come in second place, making up about 11% of its food intake. Additionally, the sharks eat smaller sharks and sea slugs.
To hunt prey, the sharks use different hunting techniques. They can coil themselves into a small ball, and then use their posterior fins as propulsive surfaces to propel themselves towards prey to catch them. Their unique long jaws that extend to the back of their heads enable them to widely open their mouths. This allows the sharks to eat prey that is up to half the length of their own bodies.
Additionally, these carnivores use a passive hunting technique. Frilled sharks will move along the sea bed with an opened mouth, enticing smaller prey with their glistening white teeth. This tactic works pretty well in the depths of darkness. They also employ the suction generated by their gills to draw in their prey.
Scientists don’t know exactly about frilled sharks’ predators. However, larger sharks in their environment might prey on them, especially the great white sharks.
4. They can float easily
The frilled sharks are solitary creatures, they only interact during mating time. These creatures possess a striking resemblance to eels both in appearance and swimming style, gracefully maneuvering through the water in a sinuous manner. However, they move quite slowly. In fact, they’re among the slowest sharks in the deep seas.
Nevertheless, these species are really good at natural buoyancy, due to their cartilaginous skeletons and generously proportioned livers filled with lipids of low density. They can effortlessly float without any need for flapping or wriggling.
Because these species live in the deep sea, they seldom interact with humans. Despite their intimidating looks, they are not dangerous to humans, displaying no signs of aggression when encountered near the shore. There is no report about sharks attacking humans.
5. They have the longest gestation period
Frilled sharks have no specific mating season since fluctuations in surface weather have no impact on the deep-sea ecosystem they inhabit. Their reproductive behavior is distinct, involving internal fertilization. During reproduction, the male employs specialized organs called claspers to deliver sperm into the female’s cloaca.
The female undergoes an exceptionally lengthy gestation period lasting up to 3.5 years, making it one of the most extended periods among animals. As ovoviviparous creatures, they do not release eggs into the ocean. Instead, the eggs hatch internally within the mother’s body. Subsequently, the female gives birth to a litter of 2-15 offspring.
Once born, the young immediately become independent, sustaining gland secretions provided by the womb. After entering the open water, these young grow rapidly.
Frilled sharks differ from many other species in terms of their sexual maturity, as it is determined by their body length rather than a specific age. The females reach maturity at lengths of 4.3-4.9 feet, whereas the males mature at the size between 3.3-3.9 feet.
These fascinating creatures also enjoy a relatively lengthy lifespan, estimated to be around 25 years.
6. Conservation Status
In recent years, the frilled shark has been the subject of numerous conservation concerns. The classification of the frilled shark by the IUCN has recently been updated to “Least Concern.” Nevertheless, the New Zealand Threat Classification System designated this shark as an “At Risk” species owing to its rarity. Their population is still mysterious.
Human activities are the main factors affecting the decline in their populations. The overfishing practices prevalent in Asian regions have led to the depletion of the shark’s main food sources. Furthermore, these sharks often become entangled in fishing nets, affected by rising water temperatures and pollution. In some cases, they are unintentionally caught as by-catch in trawler nets.
Despite the obstacles encountered, there exist encouraging indications regarding the future of the frilled shark. The fact that they can persist in the icy, unlit abyss of the ocean for countless centuries instills a sense of optimism about their ability to withstand and adapt to ever-changing environments.