Most people can name at least a few shark species, such as the famous great white, tiger sharks, and perhaps the biggest fish in the ocean—whale sharks. However, that is only the tip of the iceberg.
Sharks come in many different shapes and sizes, with roughly 440 species in the world today. And that number only continues to grow, with the latest species, named “Genie’s Dogfish,” discovered in July 2018.
Here are some of the most unusual shark species discovered so far.
Zebra sharks can be found in the western Pacific and Indian Oceans as well as the Red Sea. Divers often mistake this species for the leopard shark due to its similar black dots on a tan body. But the resemblance can only be seen on mature sharks, which have shed the yellow stripes they are born with.
With a flexible body that easily wriggles into tight spaces and whisker-like sensory organs called barbels at the front of its snout, the zebra shark has a body perfectly adapted for hunting in areas that other predators struggle to reach.
These sharks prefer to live in tropical waters and shallow reef habitats. There, they feed on crabs, sea urchins, small fish, snails, and other small invertebrates that like to hide in caves and narrow crevices.
In the absence of suitable partners, zebra sharks have been observed to reproduce through parthenogenesis (aka “virgin birth”). Scientists are still not sure why some sharks, snakes, and other creatures, which usually require a mate to reproduce, sometimes get pregnant spontaneously. For example, in 2017, a zebra shark named Leonie laid eggs that hatched three pups despite not being around a male shark in three years.
Due to its prized meat, zebra sharks are under threat of extinction in many of their endemic territories. They are sold fresh or salt-dried in markets across Malaysia, Indonesia, the Philippines, and Thailand. Zebra shark liver is processed for vitamins, while its fins are often used in shark fin soup, the traditional Chinese delicacy. Meanwhile, the species is considered abundant in Australia, where it’s widely distributed and not overfished.
Only around 60 confirmed sightings of megamouth sharks have been recorded since the species was first discovered off the coast of Hawaii in 1976. The shark was so bizarre that classifying it required an entirely new genus and family. Since then, megamouth sharks are still the only member of the Megachasma genus. It is the smallest and most primitive of the only three sharks known to feed on plankton. The other two are the basking shark and whale shark.
Megamouth sharks are “vertical migrants,” constantly changing their depth according to the day-night cycle. They spend daytime in deep waters between 120–160 meters (390–525 ft) below the surface and ascend to mid-depth waters of 12–25 meters (40–82 ft) during the night.
Due to the megamouth sharks’ elusive nature, very little is known about their population and distribution. Most of the sightings have been registered in areas of the Pacific, Indian, and Atlantic Oceans in countries such as Senegal, Indonesia, Brazil, and the Philippines. Some of the first discoveries were also on the coasts of Japan, Australia, and California.
With a much larger mouth and jaws than the rest of its body, the megamouth is not a great swimmer. To make up for it, the shark has bioluminescent lips which glow in the dark and attract prey in the deep waters where it spends most of its time. According to the Western Australian Museum, megamouth sharks also have flabby muscles, soft bodies, and poorly calcified skeletons that prevent the shark from sinking.
Horn sharks got their name from the high ridges above their eyes and the spines on their dorsal fins. They are also identified by their wide heads, blunt snouts, and dark gray to light brown coloration covered in dark brown or black spots all over. Horn sharks live in subtropical regions of the eastern Pacific, especially along the shores of California, Mexico, and the Gulf of California.
Due to their relatively small size, slow movement, and nocturnal hunting habits, horn sharks are considered to pose little to no threat to humans. But they may still bite if harassed. According to the International Shark Attack File, there is one recorded instance of a horn shark biting a human.
The horn shark population is not currently considered to be under threat. Humans do not regularly consume these sharks and usually discard them when caught as bycatch at the bottom of trawls. However, that may change in the case of significant expansion of gillnet fishery in Mexico. Due to ease of maintenance, horn sharks are also commonly kept in public and private aquariums.
In one bizarre incident, a horn shark was stolen from a Texas aquarium in July 2018. A surveillance camera captured the video of three people stealing the shark by using a stroller and disguising the animal as a baby. Later, an ad selling the shark for $300 was posted online.
Two days later, police found the truck used in the shark heist and arrested one of the three culprits. He was charged with theft, and his bond was set at $10,000. The shark was found alive and well and was returned to the aquarium.
The spotted wobbegong is one of the 12 species of carpet sharks in the Orectolobidae family. The name “wobbegong” is considered to be interchangeable with “carpet shark.”
This shark gets its name from its flat and broad body which is perfectly adapted to live camouflaged on the seabed. It is distinguished from other wobbegongs by a golden sandy to light green color and an irregular white ring pattern. Spotted wobbegongs also have 6–10 dermal lobes on each side of the head and nasal barbels which are used for sensing their surroundings.
Endemic to the coastline of Australia, spotted wobbegongs can typically be found on algae-covered rocky reefs, coral reefs, and sandy expanses down to the depths of 110 meters (360 ft). These sharks have often been sighted in waters barely deep enough to cover their bodies.
Spotted wobbegongs spend most of the day lying motionless and become more active at night when they slowly sneak up on bottom-dwelling prey such as crabs, reef fishes, rock lobsters, and octopuses. They are often observed to return to the same resting site after a night of hunting.
Although sluggish and relatively small compared to other shark species, spotted wobbegongs can be highly aggressive. There have been four confirmed unprovoked spotted wobbegong attacks on humans and another 28 bites from undetermined wobbegong species. There are also several reports of wobbegongs biting people when these animals are stepped on. Once these sharks bite, they are reluctant to let go.
Wobbegongs are frequently caught both as a target species and as bycatch in commercial and recreational fisheries. Between 1990 and 2000, catches declined by more than 60 percent. The tough and attractively patterned skin is often used as decorative leather, while the flesh of spotted wobbegongs is considered excellent for eating.
Pyjama sharks can be identified by their unmistakable combination of stripes, prominent but short nasal barbels, and dorsal fins located far back on their body. Quite small for a shark, this species hatches at the length of 14–15 centimeters (5.5–5.9 in) and typically reaches maturity at around 58–76 centimeters (23–30 in).
As a nocturnal species, pyjama sharks tend to be sluggish during the day and can commonly be found resting in caves and crevices down to depths of 100 meters (328 ft). Their prey primarily consists of crustaceans and small fish, such as anchovies.
Due to their small size and feeding habits, pyjama sharks are considered harmless to humans. And humans are not harmful to them, either. These sharks are discarded when taken as bycatch and not used for consumption.
Predators of the pyjama shark include larger shark species. But pyjama sharks are not under any significant threat of extinction and can commonly be found in the southeast Atlantic Ocean and the western Indian Ocean. They are especially common in the Cape Province of South Africa, and there are older, unconfirmed records of the species in the waters of Mauritius and Madagascar.
The angular roughshark is named after the rough, toothlike scales, known as “denticles,” that cover its body and two large dorsal fins. This rare shark moves by gliding along the seabed and stops frequently while hovering over muddy or sandy surfaces. With a preference for remaining close to the seabed, angular roughsharks tend to live at depths of 60–660 meters (200-2,170 ft).
Angular roughsharks are believed to use a suction mechanism to feed on a diet of mollusks, crustaceans, and polychaete worms. Occasional feeding on egg cases of other shark species has also been recorded. Mainly distributed in the eastern Atlantic Ocean, angular roughsharks can be found along nearly the entire western coast of Africa and Europe as well as the Mediterranean Sea.
Due to increased frequency and efficiency of bottom trawling in the Mediterranean and the northeast Atlantic during the past 50 years, angular roughsharks have become extremely rare in many of their endemic habitats and are considered critically endangered in some areas. Although the species is not specifically targeted by fisheries, angular roughsharks are regularly taken as bycatch and used for oil, human consumption, and food for fish farms.
Goblin sharks are rarely seen by humans as they live up to 1,300 meters (4,265 ft) below the surface. However, some specimens have been spotted around the depths of 40–60 meters (130–200 ft). The majority of goblin sharks ever caught were off the shores of Japan. But the species is believed to be distributed globally, with larger populations concentrated in the waters of Japan, New Zealand, Australia, France, Portugal, South Africa, Suriname, and the US.
Elongated yet flattened snouts and exceptionally sharp, long, fang-like teeth are some of the goblin sharks’ most distinctive features. Their snouts are also sprinkled with tiny electro-sensitive receptors that pick up electric fields. Goblin sharks have translucent skin, which leads to visible oxygenated blood within their capillaries and a unique coloration that ranges from pinkish-gray to bubblegum pink.
Despite its unusual appearance, the goblin shark’s most bizarre feature is its slingshot jaws. The average human mouth opens at roughly 50 degrees, while these sharks can easily manage 111 degrees. The goblin shark’s jaws jut out at a speed of 3.1 meters (10.2 ft) per second when prey comes within its reach. Then the jaws bite down before reopening, just to close again.
Scientists are still uncertain about the reason why goblin sharks open their mouths for a second time after making a kill. But it is believed that this could help with locking down more slippery prey, like squid.
It is also believed that goblin sharks may be found in British waters by 2050. There are 40 shark species living off the UK coast already, and the increase in water temperature from climate change is likely to bring new kinds of sharks from the Mediterranean and the African coast. Experts estimate that another 10 shark species, including goblin sharks, might be found in the UK in the future.
The frilled shark is one of the most primitive shark species alive today. It is believed to account for several “sea serpent” sightings because of its snakelike appearance that features a long body and tiny fins. The shark is named after the six pairs of gills which meet under its throat and create a frilly collar. But this shark’s most unique feature is its jaws, which contain 300 small, three-pronged teeth arranged in 25 rows.
Although typically found very deep below the surface, frilled sharks have also been observed at depths between 50–200 meters (160–660 ft) where they feed on squid and a variety of fish, including other sharks. The mouth and body shape of these sharks have led scientists to believe that they can consume prey more than one and a half times their own body length.
Frilled sharks have a patchy distribution across the globe. Specimens have been recorded in the waters of Scotland, Ireland, Australia, New Zealand, Japan, California, Chile, Namibia, and Norway. There have also been unconfirmed sightings in the Indian Ocean.
Due to a long gestation period and low reproductive output, frilled sharks may be under threat. Small losses of the species could have serious consequences, and individuals are regularly taken as bycatch from deep-set longlines, gillnets, and trawls. The meat is used as fish meal, eaten by humans, or discarded. So far, very little is known about the frilled shark global population size.
Despite rarely growing larger than 50 centimeters (20 in), the cigar-shaped cookiecutter shark is one of the most fearless predators on Earth. It has a brown top and a light underside, which glows to attract other fish.
However, unlike most predators, these sharks do not kill their prey. A cookiecutter shark uses the speed and movement of other fish against them and quickly turns around to take one golf-ball-sized bite out of its attacker.
This style of feeding allows the cookiecutter shark to feast on much larger creatures than itself, including seals, whales, and other sharks. The distinctive scars left by the cookiecutter’s specialized teeth scooping out a hemispherical plug of flesh allow scientists to identify what this shark’s diet consists of, and it seems like nothing is off-limits. There are even reports of this shark leaving crater marks on the sonar domes of nuclear submarines.
Cookiecutter sharks usually spend daytime around 1,000 meters (3,280 ft) below the surface and migrate upward to hunt at night. Human activities are believed to have little impact on this elusive species. It has a patchy distribution, with specimens reported in southern Brazil, Cape Verde, Guinea, Angola, South Africa, Mauritius, New Guinea, New Zealand, Japan, Hawaii, Australia, and the Bahamas.
For many years, cookiecutter sharks were considered harmless to humans because of their small size and habitat. Then came the first documented attack on a human in Hawaii in 2009. Roughly 90 minutes after sunset, one of these sharks took a bite out of a swimmer’s leg. The only two confirmed bites on humans up to that point were found on corpses.
The Greenland shark is one of the world’s largest shark species, reaching the length of 6.5 meters (21 ft) and the weight of 900 kilograms (2,000 lbs). However, its fins are small in comparison to its size. This shark’s upper jaw has slender, pointy teeth, while the bottom row consists of much larger and smoother teeth.
The coloration of the species has several variations, including gray, violet, brown, and black. Although Greenland sharks are occasionally cooked and consumed by Inuit hunters, the sharks’ skin is toxic to most other animals, including dogs. When fed the raw shark, dogs have been reported to behave drunkenly.
The majority of Greenland sharks are blind because of wormlike parasites that attach themselves to the sharks’ eyes. Luckily, these sharks live in almost complete darkness and under the ice of freezing cold waters where blindness does not make a lot of difference.
With the help of their excellent sense of smell, Greenland sharks do not struggle with finding food. Carcasses of narwhals and belugas are some of their favorite meals, but they also enjoy seals, sea lions, salmon, halibut, and herring. Sometimes, Greenland sharks participate in cannibalism.
Their life span is even more fascinating. Their eyes contain transparent, metabolically inactive tissue which has new layers added throughout the shark’s life. Analysis of the tissue of 28 Greenland sharks that were captured as bycatch has revealed them to be the longest-living vertebrates on Earth.
The estimated life span for the oldest specimen was 392 years. But accuracy may vary by 120 years, making the shark a minimum of 272 years old and a maximum of 512 years old.
Greenland sharks are mostly distributed along the coasts of countries such as Canada, Norway, Iceland, Ireland, the UK, and, of course, Greenland. Scientists are trying to discover the reason behind the long lives of Greenland sharks and what may dictate the life expectancy of other species, including humans. These sharks also appear to survive diseases that kill related species much earlier.
A lot remains unknown about these ancient predators.