Perhaps the most iconic and recognizable animal in the oceans today, it’s hard not to hear the name great white shark without a particular theme song from a certain 1976 film playing in your head.
But while Stephen Spielberg’s Jaws traumatized moviegoers for years, real great white sharks are little threat to human beings. Instead, these amazing and resourceful animals have persisted for millions of years and today subsist on a diverse diet of marine life while thriving in a variety of ocean conditions.
Appearance
Besides the plankton-eating species like the whale and basking shark, great whites are the largest of the sharks. Adult great whites can reach 20 feet in length and weigh up to 5,000 pounds. They can have up to 300 triangular teeth that are serrated to better help grip and rip. These teeth are aligned in rows so that when a tooth falls out, another can slide forward to replace it, somewhat like when we lose our baby teeth.
To help them blend into their environment, great white sharks have color-shaded coloration, a common adaptation for marine creatures no matter where they reside in the food chain. Great whites are dark gray on their backs and white on their bellies. This way, any prey looking down in the water will see the dark gray back blending in with the ocean floor. While if the shark is above its target, the white belly blends in better with the brighter water above it.
The iconic dorsal fin of the great white doesn’t cut through the surface of the water as often as television and film would lead us to believe. But it still makes an impressive sight. A fully mature great white can have a dorsal fin one meter (three feet) tall.
Diet
Great white sharks are capable of subsisting on several different prey species depending on their location and the time of year. They’re not considered picky eaters, but generalists that will go for whatever food source is available.
The majority of their diet is pinnipeds such as seals and sea lions. Fur seals are the primary food source for great white sharks off South Africa, where they will congregate in the shallow water shortly after the fur seal pups have been weaned. They’ve also been documented to feed on elephant seals and California sea lions off the west coast of North America.
If there aren’t any pinnipeds available, great white sharks will make do by hunting large ocean-going fish species like tuna and mackerel. Smaller cetaceans like dolphins and porpoises are other reliable food sources.
In very rare cases, these sharks have been documented hunting and successfully killing members of great whales such as humpbacks. This, however, doesn’t seem to be a very common food source and has only been seen on occasion.
To find food, sharks have specialized organs called Lorenzini that allow them to sense their prey’s electromagnetic field. Once they’ve located a food source, great whites use the element of surprise, usually attacking from below and sometimes flying out of the water with a seal clenched in their jaws.
Habitat
Great white sharks live in the shallowest part of the ocean, known as the epipelagic. This puts them near their favorite food sources, like seals and sea lions, that also spend the majority of their lives in these waters close to shore.
These sharks also undertake huge migrations throughout their lives. Radio-tagged great whites have been documented swimming up to 10,000 miles in a year. But while these tracks are wide-ranging, there doesn’t seem to be much of a pattern for when these sharks choose to migrate. They may move to an area with a reliable food source yearly, such as off the coast of South Africa when the fur seals pup, but there isn’t a consistent pattern like there is for most migratory species.
Great whites can be found in the Pacific, Indian, and Atlantic oceans. While they can survive in temperate waters such as the coast of Alaska, their home ranges center in more temperate and tropical waters.
Reproduction
There is still little known about the reproductive and mating habits of great white sharks. If these animals have any specific behaviors or courtships prior to mating, they have yet to be documented.
Sexual maturity occurs in males when they’re approximately ten years old or 11.5 to 13 feet long. Females mature at a slower rate and don’t hit sexual maturity until they’re between 12 and 18 years old and measure 15 to 16 feet.
Gestation is believed to be around a year long, but like a lot of our knowledge of these animals, this has not been confirmed. Great whites are viviparous, meaning they carry their fertilized eggs in the womb during gestation, similar to mammals. Birth takes place in warm water; the pups are a little over three feet long when they’re born.
Threats
As the biggest of the sharks that don’t subsist on plankton, there aren’t many animals that look at a great white as a potential food source. The one exception is the orca whale. Orcas are believed to prize great whites for their nutritionally rich livers, often moving on once they’ve consumed it. Orcas have found that by gripping the shark by the neck and turning it upside down, the shark will go into a state called tonic immobility, a form of paralysis.
Besides orcas, great white sharks don’t have any natural predators besides man. Great whites are under threat from a number of human impacts. Mainly overfishing or habitat depletion for their food sources. They are also caught in fishing nets, and the accumulation of toxins as they move up the food chain. As one of the more charismatic species, they’re subject to the sport fishing trade by those looking for fins and teeth as trophies.
Because of these threats, great whites are currently listed as vulnerable throughout most of their habitat. But their widespread migration patterns and our limited knowledge of how these populations interact leaves a lot of room for error when projecting how threatened they are.
Facts About Great White Sharks
- Great white sharks must constantly be moving to pass water over their gills
- Great white sharks a closely related to salmon sharks which are smaller version but shares several characteristics: they reside in the north pacific and eat, you guessed it, salmon.
- We don’t know how many great white sharks are left on earth, but estimates range as low as 3500.
- Great white sharks aren’t cold-blooded, instead utilizing a complex circulatory system called regional endothermy that allows them to live in colder water than other sharks.
- Scientists don’t believe great white sharks see humans as a food source. Incidental tasks are believed to be cases of mistaking a human being for a seal or curiosity. In most cases, a shark will bite only once, realize its mistake, and leave the area.
FAQs
Do sharks circle their prey?
This is one of the most common misconceptions about sharks. Just because a shark is circling doesn’t meant that it has identified food. Instead sharks may circle to get a better look at their surroundings as they have poor eyesight.
Why don’t zoos and aquariums have great white sharks?
Since great whites eat mainly warm blooded food like seals and sea lions, it would be difficult to supply a great white shark in captivity with enough of the proper food. This coupled with their long migration patterns makes them unsitable for life in an aquarium.
What is the largest great white shark on record?
The largest confirmed great white shark measured 20 feet long and was recorded in 2014.
How do great white sharks sleep?
Sharks cannot sleep in the traditional way like we do and lack eyelids altogether. Great whites have been documented “resting” in shallow water. In these cases they appear to be in a catatonic state with their bodies turned toward the current.
Can great white sharks live in freshwater?
A great white shark’s body has a very high salt content that makes them well adapted for salty waters. However, this prevents them from entering brackish or freshwater without dying.
