The Tiger shark (Galeocerdo cuvier) is an aggressive predator popular for its incredibly diverse diet. That is to say, they feed on virtually anything that comes their way.
These sharks are among the largest shark species belonging to the family Carcharhinidae. They are part of the requiem sharks. Their populations occur in most tropical and temperate waters of the world, with particular emphasis on waters around the central Pacific islands.
The Tiger shark has dark stripes running across its body resembling the body pattern found on tigers. Thus, this is the origin of its common name. These stripes are most prominent in juveniles as they fade upon attaining adulthood.
Tiger sharks are interesting species with amazing features. They are nocturnal, solitary, apex predators with a reputation for eating garbage.
The first scientific description of the tiger shark was in 1822 with Peron and Lesueur identifying it as Squalus cuvier. Later Müller and Henle renamed this species in 1937 as Galeocerdo tigrinus. They got the genus name fro the Greek words galeos meaning “shark”, and kerdo meaning “fox”. Informally, this shark is often to as the man-eater shark.
Currently, the scientific name of the tiger shark is Galeocerdo cuvier. This shark is of the order Carcharhiniformes, family Carcharhinidae, and the only extant species in the genus Galeocerdo.
The Appearance of Tiger Sharks
The tiger shark is a member of the order Carcharhiniformes consisting of sharks with two dorsal fins, an anal fin, five gill slits, and the presence of nictitating membrane (third eyelid) over the eyes. Also, as a typical requiem shark from the family Carcharhinidae, this shark has a slender shape, yet large, and powerful. In fact, it is the largest member of its family.
On average, tiger sharks attain a length of 10.6 to 13.9 feet (3.25 to 4.25 m), while weighing around 850 to 1,400 pounds (385 to 635 kg). This species exhibits sexual dimorphism with the females growing exceptionally larger in size than males.
Large recorded females measure over 16.4 feet (5 m), meanwhile, the largest male on record measure 13.08 feet (4 m). Typically large female tiger sharks can exceed 2,000 pounds (900 kg) in weight. A pregnant female caught off Australia measuring 18.08 feet (5.5 m) in length, reportedly weighed 3,360 pounds (1,524 kg).
Surprisingly, there are still reports of tiger sharks growing to an outrageous length. However, since they are not observed by researchers, there is a need to exercise caution while accepting such reports.
Note that the tiger shark is the fourth-largest extant shark species. It is behind only the whale shark (Rhincodon typus), the basking shark (Cetorhinus maximus), and the great white shark (Carcharodon carcharias).
Dispute on Size with Other Large Sharks
As for the tiger shark holding the position of the fourth-largest extant shark species, note that there are other large sharks overlapping in size with this species. For example, there is the megamouth shark (Megachasma pelagios), the greenland shark (Somniosus microcephalus), the Pacific sleeper sharks (Somniosus pacificus), and the bluntnose sixgill sharks (Hexanchus griseus).
However, the size overlapping is usually the maximum size of others compared to the average size of the tiger shark. Moreover, the study on the growth of these other sharks compared to that of the tiger shark is poor. Hence, the unclarity that leads to disagreements.
The great hammerhead shark (Sphyrna mokarran) which is in the same order as the tiger shark also overlaps in length with the tiger shark. However, they are less bulky and weigh less.
As an apex predator, tiger sharks have dentition adapted to slicing through flesh and bones. It can also crush other tough substances such as turtle shells. This shark has a unique set of teeth with prominent and very sharp serrations. The tip of the teeth points sideways particular to this species.
Tiger sharks just like most other sharks replace their teeth with new rows of teeth from time to time throughout their life. When compared to the size of the shark, the teeth are considerably shorter than that of its relatives such as the great white shark. However, the root is almost as wide as that of the great white shark. Though, the tiger shark’s teeth are arguably better adapted to slicing through prey with hard surfaces.
The tiger shark is among the sharks with a nictitating membrane which is a protective third eyelid. This is a clear eyelid that can cover the eyes. Of course, sharks lack upper and lower eyelids that can move. Hence, the nictitating membrane serving to protect their eyes.
In low light conditions, tiger sharks can enhance their vision. This is possible through the presence of the tapetum lucidum, which is a reflective layer behind the retina of this shark. The layer allows a second chance for the light-sensing cells to capture photons of visible light.
The tiger shark’s fins are generally long which helps to provide lift as the shark navigates through the water. The upper lobe of the caudal fin (tail), provides the shark with a burst of speed.
Tiger sharks’ dorsal fins are situated distinctively toward the tail side. The dorsal fin and the high back of this shark act as a pivot. They enable the shark to spin around its axis quickly.
These sharks under normal circumstances swim using little movements of the body.
Tiger sharks generally have colors ranging from blue to light green on the upper side of their body. However, the color underbelly is usually white or cream-yellow. This coloration helps the shark to camouflage when hunting for prey.
Thus, the prey rarely detects their presence since from above the shark’s blue-green color blend in with the deep color of the ocean. While from below the white color appears like that of sunlight. This phenomenon is called countershading.
The dark stripes which gave this shark its name is most prominent in juveniles. And as the shark matures, it tends to fade.
Skin and Sensitivity
Tiger sharks have small pits on their snout containing the electroreceptors ampullae of Lorenzini. These help to detect weak electrical signals generated by prey enabling them to hunt more precisely.
On the sides of their body is an organ of sensitivity known as lateral line extending the most length of the body. This sensory organ plays a major role in detecting tiny vibrations in the water. With this level of sensitivity, tiger sharks can detect hidden prey and hunt comfortably in the dark.
Habitat and Distribution Range
Tiger sharks inhabit the tropical and subtropical waters all over the world. They tend to stay near the coastal areas. These sharks are always roaming, although, they follow warmer currents. During cold periods, they stay closer to the equator.
Tiger sharks swim the deep waters that line reefs. They also move into channels often in shallower waters pursuing prey.
This shark species occur in the western Pacific Ocean. Here, it ranges from Japan in the north toward New Zealand in the south. There is also a record of tiger sharks in the Mediterranean, one time off Spain and one time off Sicily.
The tiger shark is commonly sighted in the Caribbean Sea. They are also present in the Gulf of Mexico, North American beaches, and some regions of South America. Other places with records of tiger sharks are India, China, Indonesia, Australia, and off Africa.
At What Depths Do Tiger Sharks Occur?
A recent study showed that tiger sharks are more common at a depth of 1,100 feet (350 m). Although there are reports of tiger sharks in very shallow water, they are not common. In Hawaii, these sharks have been reported in shallow waters at about 10 feet (3.05 m) deep. Also, in coastal waters, there has been a regular observation of tiger sharks at depths of 20 to 40 feet (6 to 12 m).
These sharks also dive to great depths. They have been recorded at depths very close to 3,000 feet (900 m). In all, tiger sharks are more common in deeper waters than shallow waters.
Hunting and Food Sources
Tiger sharks are apex predators feeding on top of their food chain. They are notable for their huge appetite and eat nearly anything that comes their way.
These sharks tend to swim close to the shore to feed at night and swim out into the open sea during the day. When hunting, tiger sharks use their excellent vision and well-developed sense of smell to track faint traces of blood to their source. They can also pick up low-frequency vibrations through their lateral line. This enables them to charge toward their prey with confidence, even when in murky water.
The tiger shark will usually study its prey by circling and prodding it using its snout. They often attack and eat their prey whole. When it is a large prey, these sharks will continuously bite large chunks and over time finish the whole. Their heavily calcified jaws which are broad in a nearly terminal mouth combined with the very strong, serrated teeth help them to cut through thick skins and bones.
Although tiger sharks actively hunt for food, they also scavenge, feeding on dead whales and great white sharks. Their indiscriminate style of feeding makes them often eat objects that cannot digest. For example, inedible objects including tires, oil cans, license plates, baseballs, and others found within their reach.
Tiger sharks are notable for their immense appetite. This makes them feed on various prey items. When still young, tiger sharks tend to feed mostly on small fish, jellyfish, mollusks, and cephalopods. As they mature and become adults, these sharks expand their feeding menu. They would now feed on larger prey on a regular basis.
Therefore, tiger shark adults would feed on marine mammals, sea turtles, sea birds, sea lions, crustaceans, various fish, rays, and other sharks. These sharks also attack especially, injured whales. Dolphins very much avoid areas inhabited by tiger sharks in an attempt to escape predation. Tiger sharks also prey upon dugongs. Even adult dugongs are found with scars resulting from shark attacks that failed.
This shark species, on the other hand, scavenge on dead sea animals such as whales and the great white shark.
Typical Tiger Shark Behavior
Tiger sharks are typically sluggish swimmers and stealth hunters. Though with their slow swimming behavior, they are still among the strongest swimmers of the family of sharks Carcharhinidae.
During hunting, the tiger shark approaches its prey quietly and attacks with a speed burst once it is close enough. This enables it to reach the prey aimed at fast enough before it could escape.
Of course, these sharks are well camouflaged, especially against a dark background. Moreover, their cryptic coloration helps them move undetected by prey in certain habitats.
Life Cycle of Tiger Sharks
The mating ritual of tiger sharks involves noticeable violence. This occurs as the male tries to hold the female still using his strong teeth. Breeding occurs through internal fertilization. The male inserts one of his claspers into the female’s cloaca, a genital opening giving the sperm direction.
Female tiger sharks tend to mate only once in three years. Mating generally occurs between March and May in the Northern Hemisphere. However, in the Southern Hemisphere mating extends toward November, December, even early in January.
Gestation and Parturition
The tiger shark is ovoviviparous. This means that their eggs hatch internally while they give birth to their young alive when fully developed. Gestation lasts for up to 16 months. Litters may contain 10 to 80 pups.
Growth and Lifespan
At birth, the tiger shark pups generally measure 20 – 30 inches (51 – 76 cm) in length. The male tiger sharks reach sexual maturity at a length of 7.5 – 9.5 feet (2.3 – 2.9 m). Meanwhile, the females, on the other hand, reach sexual maturity at 8.2 – 11.5 feet (2.5 – 3.5 m).
At maturity, tiger sharks would typically weigh between 180 and 290 pounds (80 and 130 kg). Tiger sharks can live for more than 12 years, however, the maximum lifespan is not known.
Interaction With Humans
Threat to Humans
Tiger sharks are considered one of the most dangerous shark species toward humans. They are responsible for several fatal attacks on humans. Because these sharks often swim to harbors, canals, and shallow reefs, they are likely to encounter humans. They also inhabit river mouths and other run-off waters.
Sharks in general rarely attack humans, therefore, tiger sharks have a low bite rate.
Attacks on Humans
Being among the most dangerous shark species, the tiger shark ranks second in the list of sharks with the most number of attacks on humans. The highest being the great white shark (Carcharodon carcharias). There are typically 3 to 4 attacks on humans by tiger sharks recorded each year in Hawaii. Although most of these bites are rarely fatal.
Humans encounter tiger sharks more often between September and November. People believe that female tiger sharks migrate toward the islands to give birth during this time.
Importance to Humans
Humans fish tiger sharks for their fins, flesh, and liver. Where the fins serve for shark fin soup, the flesh for food, and the liver for oil. Tiger sharks are also targeted for their special skin and by big-game fisheries.
Tiger sharks are victims of shark culling which was an effort to secure the tourism industry; this practice led to a severe decrease in the population of these sharks between 1959 and 2000. In all, the “shark culling” proved unsuccessful in reducing the number of interactions between tiger sharks and humans.
Other Forms of Interaction with Humans
Divers also attempt to interact with the tiger shark in several ways. For example, shark feeding and cage diving; however, shark feeding is illegal in Hawaii while cage diving is discouraged.
Some divers swim with the tiger shark outside of a cage. They even go as far as handling them to demonstrate that humans can interact with them without a cage.
In areas where tiger sharks have been heavily fished, their populations have reduced greatly. Moreover, as much as they are target species, they also occur as bycatch. Due to continuous demand for shark fin, these sharks may witness a further decrease in population.
All these made the International Union for Conservation of Nature (IUCN) to assess the tiger shark (Galeocerdo cuvier) as a “Near Threatened (NT)” species.
There are currently no specific conservation actions targeting the tiger shark. However, the Western North Atlantic is developing an increasing interest to strengthen the protection of this species. There is also the regulation restricting the reckless catching of coastal sharks including the tiger shark as the Fisheries Management Program for the U.S. Atlantic and the Gulf of Mexico.
The Tiger Shark Myth
Some native Hawaiians believe that the eyeballs of tiger sharks possess special powers of visual perception. As a result, they consider this shark to be sacred naʻaumakua which means “ancestor spirits”.
Interesting Tiger Shark Facts at a Glance
1. The Tiger Sharks Got Its Name from the Dark Stripes Across the Body
These dark stripes running across the body of tiger sharks resemble the pattern on the body of a tiger. Hence, the name “tiger shark” originated from here.
2. Tiger Sharks are Great Hunters
These sharks have electroreceptors (ampullae of Lorenzini) on their blunt snout coupled with the lateral line that helps them to detect their prey easily. Also, they have powerful eyesight which enables them to see their prey even in low light. Their high back and dorsal allows for a quick turnaround in pursuit of prey. Then, the strong jaws with very sharp and serrated teeth help them to even crack through shells.
3. These Sharks are Warm Water Lovers
Tiger sharks frequent shallow waters, although they are more common in depths up to 1,100 feet (350 m). They occur in all warmer surface waters, murky waters, and estuaries close to the coast.
4. Female Tiger Sharks Mate Only Once in Three Years
While it takes longer for female tiger sharks to reach sexual maturity than the males, they also take longer to mate. In fact, they mate only once every three years.
5. Tiger Sharks are Dangerous to Humans
Being the shark with the second-highest number of attacks on humans, tiger sharks are considered very dangerous toward humans. They only rank behind the great white shark and can inflict fatal injuries. These sharks are also capable of eating their victim after an attack.
6. Tiger Sharks are Voracious Eaters
These sharks have a huge appetite and eat almost anything that comes in their way. Sometimes, they even consume objects unfit for food due to their insatiable appetite.
7. They are Migratory Species
Tiger sharks undergo seasonal migration. They travel thousands of miles every year during temperature drop toward warmer waters.
8. These Sharks are Mostly Solitary
Tiger sharks prefer to stay alone most of the time. Though, they gather together during mating season or group feeding. Group feeding usually involves large prey.
9. Tiger Sharks Abandon Their Pups After Birth
The tiger shark does not exhibit parental care. They just abandon their young ones after birth. Consequently, many serve as prey to larger shark species.
10. There is a Myth Considering Tiger Sharks as Spirit of Ancestors
Some native Hawaii practices consider the tiger shark to be naʻaumakua meaning ancestors spirits. Thus, they see them as sacred. Further, they believe that the eyeballs of this shark species have special powers of perception.
A legend in Hawaii presented the mother of Kamehameha a great king, who requested the eyeballs of the tiger shark as she was pregnant while hoping the son she was carrying makes a great leader.
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- “Tiger Shark, Galeocerdo cuvier“, IUCN Red List of Threatened Species.
- “Tiger Shark”, Wikipedia (accessed 05 May 2020).