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By Jessica Reum
Geographic Range
Zebra sharks (Stegostoma fasciatum) live in the central, western and Indian Pacific oceans. This species is abundant in Australian coastal waters. It lives mainly over continental and insular shelves and is very common around coral reefs and sandy bottoms. It generally resides around 62 m below the surface of the ocean, but it has occasionally been found in fresh water also. (MarineBio.org, 2005)
Biogeographic Regions:
indian ocean (native 
); pacific ocean (native ).
Habitat
Stegostoma fasciatum is commonly found around warm water reefs and sandy areas. It is common along the Australian coast. It usually resides at a depth of 62 m.
These animals are found in the following types of habitat:
saltwater or marine ; freshwater .
Physical Description
(6.56 to 11.48 ft; avg. 9.02 ft)
Zebra sharks range from about 2.5 m to 3.0 m in length. The largest zebra shark captured wasabout 3.5 m in length. The body is cylindrical with lateral ridges and a tail as long as the body. The head is broad with large eyes and a transverse mouth just below them. Five gill slits are present on the side of the head. The anterior dorsal fin is larger than the posterior and the gray body is covered in dark brown spots. (Kyne et al., 2005; MarineBio.org, 2005)
Some key physical features:
ectothermic ; bilateral symmetry .
Sexual dimorphism: male larger.
Development
Newly fertilized eggs are laid on rocks at the bottom of reefs. From the time they hatch they are independent of their parents. Individuals less than 70 cm in length are rarely seen, indicating that they spend the first months of their lives at depths that recreational divers do not reach. The young sharks are darker in base color and have light stripes and spots than do adult sharks. As they age, the young lose their stripes and gain spots as their base color lightens. (MarineBio.org, 2005)
Reproduction
The breeding frequency of this species is not known.
Breeding in this species occurs year- round.
Details on the mating system of this species are not available.
Stegostoma fasciatum is oviparous. Females lay eggs, and are suspected to lay more than one egg at a time. The eggs are large, about 17 cm in diameter and are fertilized externally. The eggs hatch at about 20 to 36 cm.
Breeding in captivity has been achieved, but the eggs are hard to incubate. At the Henry Doorly Zoo in Omaha, Nebraska, 3 eggs hatched out of a group of 46 laid. Of the 46, 7 were infertile and 31 did not develop entirely. Only eight developed to a full embryo. The incubation of these eggs took about 6.5 months, which is estimated to be the same as in the wild. ("Henry Doorly Zoo et al., 1999; MarineBio.org, 2005)
Key reproductive features:
iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (external ); oviparous .
Females produce very large eggs, which can be considered a form of parental investment. In spite of this early investment, however, there is no pronounced parental care in either eggs or newly hatched offspring.
Parental investment:
pre-fertilization (provisioning, protecting: female).
Lifespan/Longevity
When S. fasciatum is kept in small tanks, the expected life span is about 9 years. When held captive in large aquariums, the average lifespan of S. fasciatum is about 25 years. In the wild, it is suspected that the lifespan is about the same, although it could be closer to 30 years. (Kyne et al., 2005; MarineBio.org, 2005)
Behavior
Stegostoma fasciatum is mostly solitary. It is a nocturnal hunter, so most of its day is spent lazily swimming around the reef. Like other bottom dwelling sharks, it can pump water across its gills through its mouth, which allows the shark to respire while stationary. It is a powerful swimmer with a tail that is as long as, if not longer than, its body. (Cavanagh et al., 2003; Kyne et al., 2005; MarineBio.org, 2005; Stead, 1963)
Home Range
These sharks do not usually swim in open water, so their territories are limited mainly to the reef at which they were hatched or reefs that are closely connected to their natal area. (MarineBio.org, 2005; Stead, 1963)
Key behaviors:
natatorial ; nocturnal ; motile ; sedentary ; solitary .
Communication and Perception
Communication in these animals has not been studied extensively. However, it is likely that some visual cues are important, especially during mating, and that tactile and accoustic cues are used.
Other communication keywords:
vibrations .
Perception channels:
visual ; tactile ; acoustic ; vibrations ; chemical .
Food Habits
Natural foods include gastropod and bivalve mollusks with smaller amounts of crabs, shrimp, and small fish. (Cavanagh et al., 2003; Kyne et al., 2005; MarineBio.org, 2005)
Primary Diet:
carnivore (eats non-insect arthropods, molluscivore ).
Animal Foods:
fish; mollusks; aquatic or marine worms; aquatic crustaceans; other marine invertebrates.
Predation
- Humans
- other large sharks
Predators of zebra sharks are other large sharks and humans. (Cavanagh et al., 2003)
Anti-predator adaptations::
cryptic .
Ecosystem Roles
These sharks are predators on a number of invertebrate and vertebrate species. Because of this, they likely affect the popultion dynamics of those species that serve as their prey.
Economic Importance for Humans: Negative
Zebra sharks are not known to have a negative effect on human economies.
Economic Importance for Humans: Positive
Zebra sharks are seen in fish markets all around Indonesia, Thailand, Malaysia, the Philippines, and India. The liver of this species is used to make vitamins, and its fins are used in many soups. (Kyne et al., 2005)
Ways that people benefit from these animals:
food ; source of medicine or drug .
Conservation Status
IUCN Red List: [link]:
Vulnerable.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
The IUCN Red List considers S. fasciatum to be a vulnerable species. The population trend is on a decline, mostly because of human hunters.
Contributors
Organisms and Populations (BS 110) [01/05 - 05/05], Michigan State University. Pamela Rasmussen 
(editor, instructor), Michigan State University. Jessica Reum (author), Michigan State University.
Nancy Shefferly (editor), Animal Diversity Web Staff.
