Brief Overview of the Great White
Shark (Carcharodon carcharias)
Recognition |
- body heavy, spindle-shaped with conical snout and narrow tail stalk
supported by stout lateral keels
- long gill slits, extending about 2/3 the depth of the throat
- mouth armed with teeth that are relatively few but large, triangular
and serrated
- second dorsal and anal fins small with pivoting bases
- caudal fin lunate, with lower lobe nearly as large as the upper
- eyes small but conspicuous, black with inconspicuous pupil
- origin of first dorsal fin over rear base of pectoral fins
- sharp demarcation between dark upper surfaces and white lower
surfaces; trailing edge of pectoral fin white, underside of pectoral
tips black; a black spot occurs at the pectoral axil ('armpit') in
some individuals
|
Size |
- Pups are 39-59 in (100-150 cm) long at birth
- Most individuals encountered are 12-16 ft (3.7-4.9 m) long.
- Maximum known length is at least 20 ft (6.1 m) and maximum known
weight is more than 2,730 lb (1,240 kg), but individuals up to 23 feet
(7.1 m) in length and 5,070 lb (2,300 kg) are probable.
- On a per-length basis, individuals from California waters seem more
massive than those from other regions - a 17.6 ft (5.4 m) female
captured off Pt. Vincente in September 1986 weighed 4,140 lbs (1,878
kg).
|
Reproduction |
- Reproductive Mode: ovoviviparous, with oophagy
- Age at Maturity: males 9-10 yrs, females 14-16 yrs
- Gestation Period: 14 months
- Number of Pups:
2-10, possibly to 17
|
Diet |
- Juvenile: bottom-dwelling teleost fishes, small sharks and rays
- Adult: sharks, rays, teleost fishes, seals, sea lions, dolphins,
whale blubber (scavenged), squids, seabirds, marine turtles, crabs,
snails
|
Range |
- Cosmopolitan in cold temperate to tropical seas
- Perhaps the most widely distributed of living sharks,
rivalled only
by the Bluntnose Sixgill (Hexanchus griseus).
|
Habitat |
- Primarily a coastal and offshore inhabitant of continental and
insular shelves, but large individuals have been recorded off oceanic
islands; often occurs close inshore to the surfline and penetrates
shallow bays in continental waters but also frequents offshore
continental islands, especially those with pinniped colonies.
- Known depth range is from the surface to at least 6,150 ft (1,875
m).
- Seems to prefer waters with sea surface temperatures of 59-72 °F
(15-22 °C); known sea surface temperature range is 45-81 degrees F
(7-27 °C); probable bottom temperature at maximum recorded depth is
39 °F (4 °C).
|
Predators |
- Humans represent the greatest threat, but this species is
occasionally preyed upon by Killer Whales (Orcinus orca) and larger conspecifics.
|
Danger to Humans |
- Extreme; this species is responsible for the vast majority of
unprovoked attacks on humans (surfers, divers, swimmers, and kayakers)
along the Pacific Coast, many of them fatal
|
Utilization |
- Fishing: classed as a gamefish, this huge and powerful shark
requires specialized equipment and tactics, including fighting chair,
130-lb (60-kg) test line, 20-ft (6-m) wire leader, 12/0 reel, and
extensive use of chum to attract it to the boat.
- Curios: jaws and teeth are much sought-after, fetching high
prices.
- Eco-Tourism: thriving eco-tourism industries have developed in
scattered locations around the globe, including (most notably) off
South Australia, South Africa, and off California. There is
currently much conflict between tour operators, who argue that they
and their clients have a right to observe White Sharks in the wild,
and researchers who argue that tourism activities interferes with
their work.
|
Relative Abundance |
- Rare to sporadic compared with other sharks, but often seasonally
abundant near large pinniped rookeries on offshore islands
|
Conservation Status |
- A regionally protected species off South Africa, Namibia, Maldives,
Australia, California, the US Atlantic Seaboard and Gulf Coast
(including Florida), and in the Mediterranean (including off Malta),
where it is illegal to pursue, capture, or possess in whole or in
part.
- International protection under CITES has not yet been granted,
allowing a sizable Black Market network to perpetuate sales of White
Shark jaws and teeth.
|
The Great White Shark is one of the sea's paramount predators and a
creature of deep fascination to many people. As sharks go, the Great White
is huge and particularly beautiful, featuring bold pigmentation, dark eyes,
and a built-in 'smile'. It also gives an impression of having a charming
personality, a strange mix of curiosity and timidity that belies its
enormity and power.
The Great White is among the most widely distributed of sharks, owing -
in part - to its ability to maintain its body temperature up to 27°F
(15°C) warmer than the surrounding seawater.
Great White Sharks often prey upon seals and sea lions in areas where
they are locally abundant. Typically, a Great White stalks such prey from
near the rocky bottom - where, from above, its black back is almost
invisible against the dark substrate - and attacks in a sudden vertical
rush, often leaping from the water in a spectacular explosion of spray and
blood.
Young juveniles of this species (less than 5 feet or 1.5 metres in
length) possess relatively slender teeth with a small basal cusplet on
either side of the main blade. Such teeth are well suited to grasping the
bottom-dwelling fishes on which they predominantly feed.
Although adults of this species are best-known as predators of marine
mammals, Great Whites are predominantly fish-eaters throughout their lives -
but even large individuals will take small prey opportunistically.
Highly curious and exploratory, Great White Sharks often investigate
novel objects in their environment - first visually and, if nothing too
frightening occurs, eventually by gentle mouthing (a habit which can prove
fatal for humans) - and will scavenge whenever possible.
At whale carcasses, this generally solitary species often establishes
temporary social hierarchies which are based largely on size. Among
similar-sized individuals, the social hierarchy is maintained through a
subtle form of body language.
Recent research has demonstrated that Great Whites are socially complex,
featuring such behaviors as parallel swimming, jaw gaping, pectoral fin
depression, and even splash-fights.
The Great White is also unusual among sharks in that it sometimes raises
its head out of the water, apparently to observe activity above the surface.
Due to its curiosity about floating objects and predation upon marine
mammals (which are air-breathing and must surface to ventilate their lungs),
the Great White is more likely to be observed by surface-bound people than
are most sharks.
Divers occasionally encounter solitary Great Whites underwater. Usually,
the shark seems to check them out visually, becomes disinterested after a
few passes, and swims away. However, one must not count on it: this is a
potentially very dangerous wild animal and divers who encounter one while
diving would be wise to leave the water immediately.
Despite the enormous popular and scientific interest in the Great White,
it remains one of the least understood of the sea's creatures. It's highly
seductive combination of large size, charisma, menace and mystery, make the
Great White Shark a modern day 'monster' that many people find irresistible.