Galeocerdo cuvierLeopard shark(Also: Tiger Shark)

Geographic Range

Tiger sharks are found in many subtropical and tropical waters, primarily from 45°N to 32°S. Tiger sharks have been sighted from the eastern coast of North America to the eastern coast of Brazil. This includes the coasts of southern North America, Mexico, and Latin America along the Gulf of Mexico. Tiger sharks also populate the coasts of China, India, Africa, Japan, and many islands of the Pacific Ocean. (Driggers III, et al., 2008; Kneebone, et al., 2008; Simpfendorfer, 2005; Wirsing, et al., 2007)

Habitat

Tiger sharks are a saltwater species. Although they prefer the sea grass ecosystems of the costal areas, they occasionally inhabit other areas due to prey availability. Tiger sharks spend approximately 36 % of their time in shallow coastlne habitats (Heithaus et al., 2002), generally at depths of 2.5 to 145 m. This species, however, has been documented several kilometers from the shallow areas and at depths up to 350 m. Females are observed in shallow areas more often than males. Tiger sharks have also been documented in river estuaries and harbors ("Tiger Shark (Galeocerdo cuvier)", 2010; Heithaus, et al., 2002; Heithaus, et al., 2006; Simpfendorfer, 2005)

  • Range depth
    2.5 to 350 m
    8.20 to 1148.29 ft

Physical Description

Tiger sharks are one of the largest carnivores in the ocean. Juveniles have tiger-like stripes, which fade as they grow older. Tiger sharks are blue or green in color with a light yellow or white under-belly. This speices has a large blunt nose on the end of a wedge-shaped head. Tiger sharks have serrated teeth, making it easy to tear flesh and crack the bones and shells of their prey. They have a heterocercal tail, meaning the dorsal lobe of the caudal fin is longer than the ventral lobe. Adults range from 3.25 to 4.25 m in length, although tiger sharks of 6 to 7.5 m in length have been documented. Female tiger sharks are on average 2.92 m in length and are smaller than males, which are on average 3.20 m in length. Adult tiger sharks typically weigh 385 to 635 kg, with largest sharks reaching 862 kg. ("Tiger Shark: Galeocerdo Cuvier", 2010; Heithaus, et al., 2007; Pratt, Jr., 1988; Read, 2010)

  • Sexual Dimorphism
  • male larger
  • Range mass
    385 to 862 kg
    848.02 to 1898.68 lb
  • Range length
    3.25 to 7.5 m
    10.66 to 24.61 ft
  • Average length
    females 2.92 m; males 3.20 m
    ft

Development

Embryos of tiger sharks are fertilized internally. A yolk sac forms around the embryos to provide necessary nutrients during the 13 to 16 month gestation period. As the yolk begins to run out near the end of the gestation period, the embryo draws nutrients directly from the mother. At birth, tiger sharks are fully developed and independent. They are born with tiger-like stripes on their back and a lightly colored yellow or white belly which allows them to blend in with the environment. These stripes fade as the juveniles reach adulthood, which is around 6 to 8 years. Males reach maturity earlier than females. ("Tiger Shark (Galeocerdo cuvier)", 2010)

Reproduction

Tiger sharks are polygynandrous, meaning males and females have multiple mates; they do not pair-bond at any time. Not much is known regarding the the behaviors of finding, attracting, and defending mates of tiger sharks. (Gruber and Myrberg, Jr., 1977; Pratt, Jr., 1988; Whitney and Crow, 2007)

Male tiger sharks reach sexual maturity when they reach an average length of 292 cm, whereas females reach sexual maturity when 330 to 345 cm in length. Females mate once every three years. Breeding seasons differ in the northern and southern hemispheres. In the northern hemisphere, females delay fertilization until March or May in order to give birth between May and June of the following year. In the southern hemisphere, females delay mating until November or January in order to give birth between February and March of the following year. Tiger sharks are one of the few species that are ovoviviparous. Females give birth to 10 to 80 pups per litter after a gestation period of 16 months. Many of these pups will not survive to adulthood. Pups weigh 3 to 6 kg at birth. (Pratt, Jr., 1988; Whitney and Crow, 2007)

Male tiger sharks have diametric testes, which are capable of synthesizing a larger amount of sperm than radial or compound testes. The females have external ovaries that appear on the epigonal organ, which is a primary lymphoid tissue in elasmobranchs. (Pratt, Jr., 1988; Whitney and Crow, 2007)

  • Breeding interval
    every three years
  • Breeding season
    Northern Hemisphere: March-May to April-June of following year. Southern Hemisphere: November-December
  • Range number of offspring
    3 to 80
  • Average number of offspring
    35-55
  • Range gestation period
    13 to 16 months
  • Range time to independence
    1 (low) minutes
  • Average age at sexual or reproductive maturity (female)
    8 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    2555 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    7 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1825 days
    AnAge

Female tiger sharks typically gives birth in a nursery, which provides protection during birth and to the young directly after birth. Tiger sharks are born independent, and mothers do not help their pups to find food, shelter or to survive. Males play no role in the lives of their offspring. Pups, however, are born with traits that help them survive without parents, including camouflage patterning, teeth to help capture prey, and speed to avoid predators. (Driggers III, et al., 2008)

  • Parental Investment
  • no parental involvement
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

The average lifespan of tiger sharks in the wild is 27 years, though some may live to 50 years of age. Tiger sharks in captivity do not live as long, a maximum of 17 to 20 years. In captivity, this species tends to die of starvation rather than old age, as food that is already dead is less appealing to tiger sharks. (Branstetter, et al., 1987; Garcia, et al., 2008; Kneebone, et al., 2008)

  • Range lifespan
    Status: wild
    50 (high) years
  • Range lifespan
    Status: captivity
    20 (high) years
  • Average lifespan
    Status: wild
    27 years
  • Typical lifespan
    Status: captivity
    17 (high) years

Behavior

Tiger sharks are a nocturnal predators and are solitary except during the mating seasons or while communally feeding on large carcasses. During these group feedings, tiger sharks have a loose social hierarchy where larger sharks feed first. Smaller sharks circle around the carcass until the larger sharks are full, then move in to feed. Violence is minimal during these scavenging feasts. In tiger sharks, the heterocercal tail, or caudal fin, is the primary source of propulsion. The caudal fin produces a downward thrust of water behind the center of balance in a shark, which should cause its head to turn upwards. However, because the tail also moves side to side, it keeps the head from turning upwards. Because of this, tiger sharks move in an S-shaped fashion. (Essapian, 1962; Gruber and Myrberg, Jr., 1977; Heithaus, 2001; Tang and Newbound, 2004; Thomson and Simanek, 1977)

  • Range territory size
    23 (high) km^2

Home Range

Tiger sharks have very large home ranges. Individuals attached with transmitters swam up to 16 km in a single day and did not return to that area for close to a year. Tiger sharks have large territories of about 23 square kilometers. (Gruber and Myrberg, Jr., 1977; Holland, et al., 1999; Thomson and Simanek, 1977)

Communication and Perception

Tiger sharks rely on electromagnetic receptors to perceive their environment and to hunt prey. Sensing organs called Ampullae of Lorenzini, located on the end of their nose, are filled with a jelly-like substance that reads electromagnetic signals. These signals are sent from the pores to the sensory nerve, and then to the brain. While hunting, tiger sharks uses this ability to detect electromagnetic signals given off by fish. Tiger sharks also use these organs to sense changes in water pressure and temperature (Plessis, 2010). Members of this species also have a lateral line on both sides of the body that runs from the gill line to the base of the tail. The lateral line reads the vibrations in the water from the movement of other animals nearby. Ampullae of Lorenzini and lateral lines also help detect electromagnetic signals from other sharks. While communally feeding on carcasses, sharks give off signals signifying dominance and thus the order in which they feed. (Kalmijn, 2000; Kneebone, et al., 2008; Plessis, 2010; Tang and Newbound, 2004)

Food Habits

The diet of tiger sharks includes mollusks, birds, snakes, crustaceans, sea turtles, and dugongs. Serrated teeth give this species the ability to penetrate the shells of sea turtles. Tiger sharks often scavenge dead or injured whales, and large tiger sharks can survive several weeks without feeding. This species most likely relies on stealth rather than strength and speed to catch prey. They are well camouflaged, allowing them to get within striking range of prey. If prey flee, tiger sharks may back off, not taking part in high-speed pursuits. However, tiger sharks are capable of short bursts of speed once their prey are within range. (Heithaus, et al., 2002; Heithaus, 2001)

  • Animal Foods
  • birds
  • mammals
  • reptiles
  • fish
  • carrion
  • mollusks
  • other marine invertebrates

Predation

Tiger sharks are some of the largest predators in the ocean and have few species feed on them. Some juvenile tiger sharks, however, fall prey to other sharks. Female tiger sharks gives birth in a nursery, which provides protection during the birthing process and to pups in the absence of parents. The coloration of tiger sharks provides camouflage against predators as well. Humans also fish for tiger sharks. (Cressey and Lachner, 1970; Driggers III, et al., 2008; Tang and Newbound, 2004)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

As top predators in their ecosystem, it is possible that tiger sharks control populations of prey species, although this has not been verified. Tiger sharks also serve as a host for remoras, which are small suckerfish. Tiger sharks and remoras share a commensal relationship: remoras attach to tiger sharks near the underbelly, and use the shark for transportation and protection. Remoras also feed on materials dropped by tiger sharks. Recently, copepods, specifically sea louse, have been discovered around the eyes of tiger sharks in Australia. (Dill, et al., 2003; Heithaus, et al., 2002; Heithaus, et al., 2006; Wirsing, et al., 2007)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Tiger sharks are a popular gamefish, which are typically captured and released for sport. They are very strong, fast and perform aerial acts when hooked. Fishing for these sharks is tiring, as tiger sharks are not quickly or easily exhausted. In some states, permits such as a saltwater fishing license allow fishermen to collect the shark as a trophy. ("Fishing for shark in the Florida Keys", 2010; "Recreational fishing regulations for Virginia's marine waters", 2010)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

Although very unlikely, tiger sharks enter shallow, populated areas of coast and attack humans on rare occasions. (Gruber and Myrberg, Jr., 1977; Heithaus, et al., 2006)

  • Negative Impacts
  • injures humans
    • bites or stings

Conservation Status

Currently, the total number of tiger sharks worldwide is unknown. However, they are listed as near threatened on the IUCN Red List. One major initiative to protect this species has been the limitation of the number of sharks taken by fisherman (i.e., one per vessel with a specific license). ("Recreational fishing regulations for Virginia's marine waters", 2010)

Contributors

Kyah Draper (author), Radford University, Karen Powers (editor), Radford University, Gail McCormick (editor), Animal Diversity Web Staff.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

delayed fertilization

a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

electric

uses electric signals to communicate

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

internal fertilization

fertilization takes place within the female's body

magnetic

(as perception channel keyword). This animal has a special ability to detect the Earth's magnetic fields.

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

nomadic

generally wanders from place to place, usually within a well-defined range.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

ovoviviparous

reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

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Branstetter, S., J. Musick, J. Colvocoresses. 1987. A comparison of the age and growth of the tiger shark, galeocerdo-cuvieri, from off virginia and from the northwestern Gulf-of-Mexico. Fishery Bulletin, 85/2: 269-279.

Cressey, R., . Lachner. 1970. The parasitic copepod diet and life history of diskfishes (Echeneidae). Copeia, 1970/2: 310-318.

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Heithaus, M. 2001. The Biology of Tiger Sharks, Galeocerdo Cuvier, in Shark Bay, Western Australia: Sex Ratio, Size Distribution, Diet, and Seasonal Changes in Catch Rates. Environmental Biology of Fishes, 61/1: 25-36.

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Plessis, A. 2010. "Sharks- Electroreception" (On-line). Accessed September 23, 2010 at http://www.sharks.org.za/electroreception.html.

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