|Scientific name||Chlamydoselachus anguineus||Weight||90 kilograms (200 pounds)|
|Pronunciation||frild shahk.||Length||2.0 meters (6.6 feet)|
|Classification||Chondrichthyes, Hexanchiformes, Chlamydoselachidae||Location||Pacific, Atlantic and Indian Ocean|
The Frilled Shark
The frilled shark is a strange-looking, deep-water shark species that looks like it’s from a different time period — and that’s because it is.
This enigmatic shark evolved in the ancient seas of the Late Jurassic Period, about 150 million years ago, and has remained relatively unchanged since then.
The two species of frilled shark that are still living today inhabit the deep waters of the Pacific and Atlantic Oceans.
The shark’s common name references the row of six red-line gills on both sides of the shark’s body that have a frill-like appearance.
The frill shark spends most of its time feeding on cephalopods, smaller sharks, and fish near the bottom of the ocean.
But it occasionally swims to the surface for food, during which it may get caught accidentally in fishing nets and trawls.
The frilled shark is not commercially significant and rarely encountered in the wild.
Consequently, very little is known about their ecology and behavior.
In this article, we’ll explore some of the few facts we do know about this enigmatic shark species.
Taxonomy and Classification
The scientific name of the frilled shark is Chlamydoselachus anguineus.
This shark is also sometimes referred to as the lizard shark.
It belongs to the Chlamydoselachus genus along with Chlamydoselachus africana (also known as the southern African frilled shark).
Both species are the only living members of this genus, although they have several close relatives that are now extinct.
The Chlamydoselachus genus is classified in the family Chlamydoselachidae, and it’s the only genus in this family.
The frilled shark belongs to the order Hexanchiformes, a group of sharks that evolved several million years ago.
This order also includes the equally primitive cow sharks (family Hexanchidae).
The frilled shark has been around for at least 80 million years, which makes it one of the oldest living shark species.
It demonstrates a wide range of primitive features reminiscent of ancient shark species.
These traits suggest that the frilled shark has changed little despite being around for millions of years.
The frilled shark is an ancient-looking shark with a long, eel-like body.
Its body is cylindrical and slender, which allows it to move easily through the water and navigate the narrow crevices of the deep-sea environment where it lives.
In fact, the species name anguineus is from a Latin word that describes a snake or dragon.
This shark can grow to an average length of nearly two meters (6.6 feet).
The frilled shark has a broad and flat head, similar to the head of a lizard.
It also has a short, rounded snout with a large mouth that can open very wide and is lined with multiple rows of three-pronged teeth.
The teeth number up to 300 and are arranged in widely spaced rows in the shark’s mouth.
The upper jaw has about 19 to 28 tooth rows, while the lower jaw has 21 to 29 tooth rows.
One of the most notable features of this shark is the unique appearance of its gill slits.
The slits are located behind the shark’s head and extend down the side of its throat on both sides of its body, forming a sort of collar that almost meets on the underside of the shark’s body.
The gill slits are six in number, and they have a distinctive frilly margin, which earned the shark its name.
Most modern sharks have five pairs of gill slits, so the frilled shark’s additional gill slits are considered a primitive feature.
Frilled sharks typically have a dark brown or grayish-black coloration on their upper side, which helps them blend into the dark depths of the ocean.
Their ventral side is usually lighter, often a pale cream or beige color.
The shark’s dorsal and pelvic fins are positioned far back on its body, almost close to the anal fins.
They also have short and rounded pectoral fins.
The caudal fin forms a triangular tail without a lower lobe or ventral notch.
The tail has dermal denticles, which the shark can enlarge and help the shark’s locomotion.
There’s a pair of long folded skin on the underside of the frilled shark’s body.
The pair of thick skin are separated by a groove and run through the entire length of the shark’s belly.
The exact function of this ventral skin fold isn’t known.
Habitat and Distribution
The frilled shark is a deep-sea dweller found in the Atlantic, Indian, and Pacific oceans.
This shark is typically found at depths ranging from 200 meters (656 feet) to an astonishing 2,000 meters (6,561 feet) or more.
Frilled sharks are adapted to cold waters with temperatures ranging from about four to seven degrees Celsius (39 to 45 degrees Fahrenheit).
Frilled sharks have an almost worldwide distribution, but their populations are patchy and isolated to specific areas.
In the Atlantic Ocean, frilled shark populations are known to occur in the outer continental shelves and slopes of Norway, Western Ireland, Northern Scotland, and Northern Namibia.
Populations in the eastern Pacific Ocean are found in Southern California and Western Chile.
In the West Pacific, frilled sharks live off southeast Japan, eastern Australia, and New Zealand.
Some populations may also exist in parts of the western Indian Ocean, but these are not very well-known.
Behavior and Social Structure
Frilled sharks live in deep-sea environments, so they’re rarely encountered in their natural habitat.
Consequently, very little is known about their behavior and how they live.
Although they have long, streamlined bodies, frilled sharks are known for their slow and sluggish swimming style.
This sort of energy-efficient movement is well-suited to the deep-sea environment where they live since prey is scarce, and sudden bursts of speed are not necessary.
Frilled sharks are opportunistic predators that primarily feed on deep-sea species such as fish, squid, and other marine organisms.
They mostly hunt by ambush, waiting for their prey to swim and lunging at prey when they’re within striking distance.
Since these sharks are rarely observed in their natural habitat, their exact social behavior is not known.
However, given their deep-sea habitat and relatively low population densities, frilled sharks likely lived solitary lifestyles.
Each individual roams over vast areas of the ocean in search of food and only interacts with other frilled sharks when mating.
Frilled sharks are thought to be primarily nocturnal, which means most of their feeding activities occur at night.
During the day, they tend to retreat to deeper, darker waters where they are less likely to encounter predators and competitors.
Diet and Feeding
Frilled sharks have a varied diet that depends on the food availability in their habitat.
They are known to consume various fish species, especially those found in their deep-sea habitat.
These may include smaller deep-sea fish species, sharks, and other cartilaginous fishes.
Squids also form a significant part of the frilled shark’s diet.
The sharp, backward-pointing teeth of the frilled shark are well-suited for grasping and holding onto these slippery cephalopods.
In addition to squid, frilled sharks may also prey on other cephalopods, such as octopuses and cuttlefish, which are abundant in deep-sea environments.
Interestingly, frilled sharks have been known to migrate vertically to higher levels of the water column (between 50 and 200 meters) to find prey.
Since they live close to the sea floor, frilled sharks may occasionally act as scavengers, feeding on carrion that sinks to the bottom of the sea.
Frilled sharks capture their prey by lunging and engulfing it with their wide gape.
Once a prey gets caught in the frilled shark’s jaws, it’s almost impossible for it to escape.
They hunt with their mouth open, and the dark and light contrast of the shark’s teeth may help them lure prey towards their gaping maw.
Reproduction and Life Cycle
Very little is known about the frilled shark’s life cycle and reproductive behavior.
However, they seem to have no predefined breeding season.
Male frilled sharks mature when they’re about 1.0 to 1.2 meters (3.3 to 3.9 feet) long.
Mature females are bigger, with an average length of about 1.3 to 1.5 meters (4.3 to 4.9 feet) at maturity.
Specific courtship displays or rituals in frilled sharks have not been observed or documented.
However, it is probably similar to that of other shark species, with males engaging in a wide range of behaviors to attract females, such as swimming alongside or nuzzling them.
Ovulation in female frilled sharks occurs fortnightly.
Like other shark species, frilled sharks are ovoviviparous.
This means females give birth to live young instead of laying eggs, but the developing fetus does not take nourishment from the mother as mammals do.
Instead, frilled shark babies develop in membranous egg sacs within the mother’s body and feed on yolk while they develop.
Frilled sharks have the longest gestation period of any known living animal.
They’re pregnant for up to 42 months — over three years!
About 2 to 15 pups are born at the end of the long gestation period, but an average of 6.0 pups is more common.
Each pup measures about 40 to 60 centimeters in length at birth.
The extended gestation period allows the juvenile frilled shark pups to develop all the specialized adaptations needed for deep sea life before birth.
This includes the development of gill slits, fully-formed jaws, and other features needed to survive in the deep-sea environment.
Juvenile frilled sharks are fully independent at birth, capable of hunting prey on their own.
Ecological Role and Interactions
Frilled sharks are top predators in their deep-sea habitat.
They prey on various organisms, including fish, squid, and other marine invertebrates.
This makes them an essential part of the deep-sea food web.
Frilled sharks are highly adapted to the extreme conditions of the deep sea environment, including cold temperatures, high pressure, and darkness.
However, they are also known to venture to higher levels of the water column in search of prey.
Frilled sharks may also act as scavengers.
They get rid of carrion and other animal matter that sinks to the bottom of the ocean, contributing to the cycle of nutrients within their ecosystem while also cleaning up the sea.
Little is known about the threats and predators faced by the frilled sharks itself.
However, given its size, this shark is probably perfect prey for larger sharks in the same region, especially when it ventures to shallower ocean depths where larger predators like the great white shark are more abundant.
Conservation Status and Threats
The frilled shark is currently classified as a species of least concern on the IUCN Red List of endangered animals.
Although this shark species’ exact population trend is unknown due to their elusive nature and deep-sea habitat, it is assumed that they have a relatively stable population.
There is generally minimal information available to determine the species’ risk of extinction with absolute certainty.
Human activities like deep-sea mining and bottom trawling put deep-sea species like the frilled shark at risk.
These activities disturb their habitat and affect this shark’s typical food sources.
Commercial fisheries do not target frilled sharks, but they may be incidentally caught by deep-sea fishing operations targeting other species.
Although there is limited information about how often this happens, it can still threaten their populations.
Frilled sharks also have a low reproductive rate.
A relatively small number of offspring are produced after a long gestation period.
This makes them particularly vulnerable to population decline due to these disruptive human activities.
Efforts aimed at protecting the frilled sharks specifically are limited.
However, conservation groups and governments worldwide are investing efforts into protecting deep-sea ecosystems’ overall health and integrity.
This includes preserving essential deep-sea habitats and regulating activities like deep-sea trawling and other activities that may indirectly affect frilled shark populations.
Unique Adaptations and Survival Strategies
The frilled shark is known for its elongated, eel-like body, which is highly efficient for a deep-sea species that needs to navigate narrow crevices and deep-sea canyons in its habitat.
This body shape allows it to move gracefully through the water while conserving energy.
As a predator, having a streamlined body also helps the frilled shark access tight spaces where prey may hide.
Another significant adaptation of this shark is its frilled gill slits.
Frilled sharks have six pairs of gill slits, compared to five for most modern sharks.
These frilly gill slits increase the surface area of the shark’s gills for oxygen absorption, enhancing the shark’s ability to extract dissolved oxygen from the deep-sea water, where oxygen levels tend to be very low.
Frilled sharks also have an exceptionally flexible jaw that can open very wide.
The jaw is lined with backward-pointing teeth, which are effective for elusive prey like squid, which can be challenging to capture.
Cultural Significance and Human Interactions
Frilled sharks are elusive and enigmatic shark species.
Their deep-sea habitat makes encounters with humans rare and unlikely.
The frilled shark is sometimes caught accidentally as a bycatch of commercial fisheries targeting other fish species such as sea bream and gnomefish.
The shark can be a nuisance to commercial fisheries, sometimes damaging fishing nets in search of food.
Captured frilled sharks can be used as fishmeal and processed as meat.
Although they have a scary, other-worldly appearance due to their primitive nature, frilled sharks pose no significant threat to humans.
They typically live thousands of feet below the surface, so encounters with humans are highly unlikely.
Future Prospects and Research
There’s still a lot we are yet to know about the frilled shark.
It was observed in its natural habitat for the first time in 2004 and was caught on video in 2007.
Although this shark has captured the interest of marine biologists, scientists, and deep-sea explorers due to its ancient lineage, the challenging nature of the frilled shark’s habitat makes studying them challenging.
Primitive species like the frilled sharks are significant to scientific research.
Learning more about their genetics and relationship to other species can help us understand how ancient shark species lived in the prehistoric past and the unique adaptations that aided their survival.
Research on frilled sharks can also contribute to our understanding of deep-sea ecosystems.
Fortunately, more recent advancements in deep-sea exploration technology may help provide more data about this elusive shark species in the future.
Advanced submersibles, remotely operated vehicles (ROVs), and other recent technological advancements will lead to more sightings and observations of frilled sharks in their natural habitat.
This will provide valuable insights into their behavior, distribution, and ecological interactions with other species in their ecosystem.
The frilled shark is a strange, primitive-looking shark species found in the deep waters of the Atlantic, Pacific, and Indian oceans.
The species gets its name from the row of grill-like red-lined gills on both sides of its body.
Frilled sharks are active predators of deep-sea habitats.
They prey mainly on small fish, squids, and other deep-sea species.
Currently, very little is known about this shark species because of how challenging it is to study them in their natural habitat.
We do know that this shark species reproduces very slowly, with a long gestation period that may last for up to 3 years.
This means they’re particularly at risk of extinction due to human activities such as deep-sea fishing.
Consequently, there’s a need to invest more effort into learning more about this ancient shark species and contribute towards protecting them.