What Are The Most Common Shark Species?
Sharks. Big? Check. Cold-blooded? Check. Toothy? Check!
Although these are the attributes most commonly associated with sharks, not all of them were created equal. Did you know that there are more than 1000 species of shark in the earth’s waters, with more being discovered each year? In fact, sharks vary enormously from one species to the next.
If you’re curious to find out more about the different types of sharks, read on to get the lowdown on everything from the Tiger Shark to the Hammerhead!
Great White Shark
If you’ve seen Jaws, you’ll recognise this shark. Found in cool, coastal waters around the world, great whites are one of the largest predatory fish on Earth.
Great white sharks grow to an average of 15 feet in length, although specimens exceeding 20 feet and weighing up to 5,000 pounds have been recorded!
They have white underbellies - hence the name - while their upper bodies are slate-gray to blend in with the rocky coastal sea floor.
Great whites are streamlined, torpedo-shaped swimmers with powerful tails that can propel them through the water at speeds of up to 15 miles per hour. They can even leave the water completely, breaching like whales when attacking prey from underneath.
Great white sharks are known to be highly migratory, with individuals making long migrations every year. In the eastern Pacific Ocean, great whites regularly migrate between Mexico and Hawaii. Like in many highly migratory species, the very largest individuals are female.
Highly adapted predators, great whites are probably most easily recognised by their mouths, lined with up to 300 serrated, triangular teeth arranged in several rows. They also have an exceptional sense of smell to detect prey and some of their organs can even sense the tiny electromagnetic fields generated by animals.
The novel Jaws by Peter Benchley and its subsequent film adaptation by Steven Spielberg depicted the great white shark as a ferocious, blood-thirsty man-eater. However, humans are not the preferred prey of the great white shark...
In reality, they feed on other sharks, crustaceans, molluscs, and sea birds. Larger white sharks will also prey on sea lions, seals, and small toothed whales like orcas. The species has even been seen feeding on dead whales.
That being said, great whites are nevertheless responsible for the largest number of reported and identified fatal unprovoked shark attacks on humans - so if you come across one, it’s probably best to make a swift getaway!
Whale Shark
Now for a much friendlier and, frankly, cooler looking species.
The whale shark is easy to recognise thanks to its “spots and stripes” design! Yep, this species sports a grey or brown upper body covered in white spots dispersed evenly across interlocking horizontal and vertical white stripes.
The whale shark's flattened head sports a blunt snout above its mouth with short barbels protruding from its nostrils. Its belly is white and it has two dorsal fins set rearward on its body, which ends in a large dual-lobbed caudal fin (or tail).
A slow-moving, filter-feeding carpet shark, the whale shark is found in open waters of the tropical oceans and is rarely found in water below 21 °C (70 °F).
Studies looking at vertebral growth bands and the growth rates of free-swimming sharks have estimated whale shark lifespans at 80–130 years!
In order to eat, this beast juts out its formidably sized jaws and passively filters everything in its path. The mechanism is theorized to be a technique called “cross-flow filtration,” similar to some bony fish and baleen whales. They feed almost exclusively on plankton and small fish, and pose no threat to humans.
Although massive, whale sharks are docile fish and sometimes even allow swimmers to hitch a ride! They are currently listed as a vulnerable species; however, they continue to be hunted in parts of Asia, such as the Philippines.
Tiger Shark
How to make a shark sound more scary? Name it after another sharp-toothed predator!
Tiger sharks are so named because of the dark, vertical stripes that are found on the young. As these sharks mature, the lines begin to fade and almost disappear.
The tiger shark is a solitary, mostly nocturnal hunter. It is notable for having the widest food spectrum of all sharks, with a range of prey that includes crustaceans, fish, seals, birds, squid, turtles, sea snakes, dolphins, and even other smaller sharks.
It also has a reputation as a "garbage eater", consuming a variety of inedible, man-made objects that linger in its stomach. Although they are apex predators (aka predators at the top of the food chain), tiger sharks are sometimes taken as prey by groups of killer whales.
Like great whites, tiger sharks also have a reputation as man-eaters - probably because of their formidable set of teeth! Admittedly, they are second only to great whites in attacking people but because they have an almost completely undiscerning palate, they are not likely to swim away after biting a human, as great whites frequently do.
Unfortunately, tiger sharks are regularly hunted—mainly for their fins, but also for their liver oil. Since they have a low reproduction rate, overfishing is a major threat to tiger shark populations. Juveniles are often caught unintentionally as bycatch, which is detrimental to the next generation. The decreasing population of tiger sharks has led the IUCN to list the species as near threatened.
Great Hammerhead
Next up, a shark with a blunt, heavy weapon fixed to its face! Just kidding...
The great hammerhead shark is the largest of all hammerhead species, reaching a maximum known length of 20 feet (6.1 m) and weight of 991 pounds (450 kg). The species is distinguished from other hammerheads by its nearly straight hammer-shaped head (known as a cephalofoil) that has a prominent indentation in the middle.
Great hammerhead sharks are apex predators and can be found worldwide in coastal, warm waters that are 68° F (20° C) or higher. Unlike scalloped hammerhead sharks, great hammerhead sharks are solitary and migrate long distances upward of 756 miles (1,200 km) alone.
Their wide-set eyes give them a rather strange appearance but actually make for a better visual range than most other sharks. Moreover, they have highly specialized sensory organs spread over their wide, mallet-shaped head, meaning they can thoroughly scan the ocean for food.
One group of these sensory organs is known as the ampullae of Lorenzini, which allows sharks to detect, among other things, the electrical fields created by prey animals. The hammerhead's increased ampullae sensitivity allows it to find its favorite meal, stingrays, which usually bury themselves under the sand.
Although potentially dangerous, the great hammerhead rarely attacks humans. It sometimes behaves inquisitively toward divers and should be treated with respect.
This shark is heavily fished for its large fins, which are extremely valuable on the Asian market as the main ingredient of shark fin soup. As a result, great hammerhead populations are declining substantially worldwide, and the species has been assessed as Critically Endangered by the International Union for Conservation of Nature (IUCN) as of 2019.
Blue Shark
Next up, one of the cutest shark species on our list...
Blue sharks are curious, open-ocean predators that can be found throughout the globe, from the tropics to cold temperate waters. They spend most of their lives far from the coast and are truly a pelagic species (that’s animals that live in the upper waters of the open sea, FYI).
The name comes from the shark’s blue skin, making this species stand out among sharks.
Blue sharks are known to be highly migratory, with individuals making several trips across entire ocean basins throughout their lifetimes. Experts believe that blue sharks use their large pectoral fins (horizontal fins growing out from either side of the body) to ride long currents, conserving energy as they migrate.
Blue sharks go on these long migrations for two reasons: to reach areas of dense food resources and to find potential mates. For most of the year, males and females of this species live in different places. Only during the mating season do they come together, briefly, and reproduce via internal fertilization.
Fun fact: baby sharks are called pups! Blue sharks have large litters - producing anything from 25 to over 100 pups. This species has a relatively short lifespan, too: around 20 years.
They feed primarily on small fish and squid, although they can take larger prey. The blue shark is relatively unaggressive but is very curious and will approach divers and spearfishers, especially if food is available. According to the ISAF, the blue shark is responsible for thirteen unprovoked shark bites worldwide.
Zebra Shark
Not to be confused with the similar-looking leopard shark, here’s another species named after a much less predatory animal!
The zebra shark’s distinctive appearance, which changes as the shark reaches maturity, frequently bamboozles divers who often mistake it for the leopard shark. While zebra sharks are born dark brown with yellowish stripes, as they reach adulthood, they shed their stripes for small black dots against a tan body, closely resembling the leopard species.
They are nocturnal and spend most of the day resting motionless on the seafloor. They live in shallow coral reefs in tropical waters and at night they wriggle into narrow crevices and caves in search of food - namely molluscs, crustaceans, small bony fishes, and possibly sea snakes.
The zebra shark is oviparous: females produce several dozen large egg capsules, which they anchor to underwater structures via adhesive tendrils.
They are generally harmless to humans but they may bite if provoked (don’t we all!). According to the International Shark Attack File, there has been one documented unprovoked attack on a human. This attack, however, resulted in no injuries.
The zebra shark is taken by a wide range of inshore fisheries and prized for its meat, which may be sold fresh or salt-dried in markets throughout Indonesia, Thailand, Malaysia, Philippines, and elsewhere. Its liver is also processed for vitamins and its fins are chopped off for use in shark fin soup, a traditional Chinese delicacy.
Although the practice of shark finning is illegal in U.S. waters, fins can still be bought and sold from unsustainable foreign fisheries that are lacking or have ineffective shark finning bans.
The combination of these practices is driving down zebra shark populations in most of their range, and they are considered endangered by the IUCN Red List. However, in Australia, the species is considered of Least Concern because it has a wide distribution and is not heavily fished.
