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.
- Biogeographic Regions
- nearctic
- oriental
- ethiopian
- neotropical
- australian
- indian ocean
- atlantic ocean
- pacific ocean
- Other Geographic Terms
- cosmopolitan
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
- Habitat Regions
- temperate
- tropical
- saltwater or marine
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.
- Other Physical Features
- ectothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
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.
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.
- Mating System
- polygynandrous (promiscuous)
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.
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.
- Key Reproductive Features
- seasonal breeding
- sexual
- fertilization
- ovoviviparous
- delayed fertilization
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.
- Parental Investment
- no parental involvement
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
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.
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.
- Key Behaviors
- natatorial
- nocturnal
- motile
- nomadic
- solitary
- dominance hierarchies
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.
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.
- Perception Channels
- tactile
- vibrations
- electric
- magnetic
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.
- Primary Diet
-
carnivore
- eats non-insect arthropods
- molluscivore
- 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.
- 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.
- Remoras Echeneidae
- Sea louse Caligus oculicola
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.
- 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.
- 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).
Additional Links
Contributors
Kyah Draper (author), Radford University, Karen Powers (editor), Radford University, Gail McCormick (editor), Animal Diversity Web Staff.
- 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.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- oriental
-
found in the oriental region of the world. In other words, India and southeast Asia.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Australian
-
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- 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.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- 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.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- 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.
- 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.
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- pelagic
-
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
- 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.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- 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.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- 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
- fertilization
-
union of egg and spermatozoan
- internal fertilization
-
fertilization takes place within the female's body
- 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.
- 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.
- natatorial
-
specialized for swimming
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- nomadic
-
generally wanders from place to place, usually within a well-defined range.
- solitary
-
lives alone
- dominance hierarchies
-
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
- visual
-
uses sight to communicate
- electric
-
uses electric signals to communicate
- tactile
-
uses touch to communicate
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- electric
-
uses electric signals to communicate
- magnetic
-
(as perception channel keyword). This animal has a special ability to detect the Earth's magnetic fields.
- carrion
-
flesh of dead animals.
- 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.
- food
-
A substance that provides both nutrients and energy to a living thing.
- carnivore
-
an animal that mainly eats meat
- molluscivore
-
eats mollusks, members of Phylum Mollusca
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