12 Facts About Great White Sharks

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In 1974, Peter Benchley released Jaws, a horror novel that sold 20 million copies, spawned an iconic film—and catapulted the great white shark (Carcharodon carcharias) to infamy. Although the book brought him fame and fortune, Benchley came to rethink its negative portrayal of great whites: The author-turned-conservationist said in 1995 that if he was writing his book then, “The shark … could not be the villain; it would have to be written as the victim.” The great white is now classified as a vulnerable species. Read on to find out why the truth about Carcharodon carcharias is often stranger—and always more compelling—than the fiction that obscures it.

1. EYE-ROLLING IS A DEFENSE MECHANISM.

Many sharks protect their eyeballs with a pair of clear lid structures called nictitating membranes, which act like protective, transparent eyelids. But not great whites—they don't have the membranes. Instead, their eyeballs roll backwards into the skull reflexively when a shark bites into a thrashing victim [PDF]. This exposes the sclerotic coat, a fibrous tissue that surrounds the eye.

2. SOME REPORTS ON THEIR SIZE ARE KIND OF FISHY.

The great white is a huge fish, no question—but some claims about its maximum size are probably exaggerated. In 1870, one zoologist measured the disembodied jaws of a large adult and estimated that the whole shark must have been 36.5 feet long. But a modern reevaluation—in which the jaws were compared to those from other dead sharks—showed that the creature’s actual length was probably about 16.5 feet, and the reports of the giant shark were likely a printer’s error.

And then there's the Cojímar specimen, a great white captured and killed near Cuba in the early 1940s. Those who saw it in person said the fish was 21 feet long and weighed 7100 pounds. Since then, the claim has been disputed by fish experts who, using an available photo, calculated that the animal’s real length was also in the ballpark of 16 feet. According to biologist Jose Castro’s book The Sharks of North America, the largest great white “believed to have been measured reliably” stretched 19.6 feet long. When it comes to weight, big males have been measured weighing up to 2819 pounds while the largest female weighed 4343 pounds.

3. GREAT WHITES ARE CLOSELY RELATED TO MAKOS.

According to a 2016 paper, there are 509 species of shark divided into nine orders and 34 families. Great whites belong to the lamnidae family, which contains only four other species: the porbeagle, the salmon shark, the longfin mako, and the shortfin mako. All five sharks have conical snouts, eyes that look solid black, and lengthy gill openings. They share a couple of other things as well—including a method for trapping body heat.

4. THEY CAN STAY WARM IN FRIGID WATER.

Most shark species have no direct control over their body temperatures; they're about as hot or cold as the water they’re swimming in. But there are a handful of species—the entire lamnidae family included—that are endothermic, meaning they can consistently maintain high body temperatures even in cold water.

The great white and its relatives have their powerful muscles to thank for this talent. The muscles naturally produce heat as they contract, warming up blood in that area, which is then redistributed to other parts of the body. This allows great whites to keep their core body temperature as high as 25 degrees (Fahrenheit) warmer than the ambient water, which means they can thrive in bitterly cold places. And when muscles are kept warm, they work more efficiently, so great whites can swim faster and farther than many other sharks. On the flip side, great whites need to consume a huge amount of calories in order to keep their body temperatures up.

5. NOT ALL GREAT WHITES GO AFTER THE SAME FOODS.

Great whites have varied diets and not all individuals share the same food preferences. But in general, younger sharks mostly eat fish and squids while older, larger sharks tend to go after big targets like marine mammals. Catching small fish and biting into fatty seals are, of course, two very different tasks. This explains why juvenile white sharks have narrower teeth than adults do—the better to pierce the skins of slippery fish. Living sharks of every species possess multiple tooth rows and are constantly replacing old chompers with brand new ones. As a great white matures, its incoming teeth become broader, serrated, and triangle-shaped, allowing great white adults to tear large chunks of meat off their victims.

6. GREAT WHITES CAN GET AIRBORNE.

Fatty, calorie-rich pinnipeds like seals and sea lions are common prey for large great whites, which typically attack from below in an explosive burst. The top speed of a great white is over 20 miles per hour, and during seal hunts, they can burst completely out of the water—a feat known as breaching—which leads to the successful capture of a pinniped 40 to 55 percent of the time, depending on lighting and other variables.

7. THEY DINE ON THE WORLD’S BIGGEST FISH.

In the 1960s, a 14.7-foot great white shark was captured near an Australian whaling station and, when it was dissected, two mysterious bones were found in its stomach. They were later identified as vertebrae belonging to an adult whale shark that was estimated to be 28 feet long. These filter feeders can grow to be 40 feet long and weigh at least 7 tons; experts now think that great whites are scavenging on floating whale shark carcasses rather than hunting the fish.

8. ATTEMPTS TO PUT THEM IN CAPTIVITY HAVEN’T GONE WELL.

Certain sharks thrive in aquariums; great whites don’t. Every single great white that’s been placed in captivity has either died or been released after a brief stay. The Okinawa Aquarium, Sea World San Diego, and the now-defunct Marineland of the Pacific are among the facilities which experimented with captive white sharks at some point or other. At the Monterey Bay Aquarium, one specimen spent a record-breaking six months living in a million-gallon tank. Once she began stalking other display fish, however, she was set free. Several different factors make great whites ill-suited for captivity. To breathe, the animals must be in constant motion to push water over their gills, and aquariums don’t always offer enough space for this. Other issues include the species’ famously large appetite and its tendency to run into glass walls.

9. DESPITE MYTHS TO THE CONTRARY, GREAT WHITES CAN GET CANCER.

There’s a myth that great whites and other sharks are immune to cancer, which has had some unfortunate real-world consequences. Assertions that shark cartilage is an edible cancer cure has led to mass harvesting of the vulnerable fish.

For the record, clinical tests have shown that ingesting shark cartilage in no way treats any form of cancer. Cancer has been documented in more than 20 shark species, including the great white: The first reported instance of a tumor-plagued great white was announced in 2015.

10. THEY TRAVEL VAST DISTANCES.

The great white inhabits many of the world's oceans, but they're most often found in waters with surface temperatures from 59°F to 72°F. The species also migrates seasonally. Some travel from South Africa to Australia and back every year. Other great whites cross the Atlantic, making long treks between Cape Cod, Massachusetts and the Azores, 2300 miles away. And each winter, scores of them leave Californian waters for a point researchers have nicknamed “the white shark café.” Located halfway between Hawaii and Mexico, this region doesn’t appear to offer much in the way of food, but the sharks remain there from April to July. Data from tagged great whites tells us that the males go on rapid, deep dives multiple times per day while hanging out in this area. Nobody knows why the white shark café is such a hot destination—but it might be a place where the fish gather to breed.

11. ORCAS PREY ON THEM.

When great whites get knocked upside-down, they freeze up and exhibit “tonic immobility,” a state of semi-consciousness. There’s at least one animal that can exploit the vulnerability. On October 4, 1997, an orca was seen barreling towards a great white shark (which measured 9 to 13 feet long) near one of California’s Farallon Islands. A human onlooker filmed the orca dragging the stunned fish around on its backside. Eventually, it let go [PDF], and then ate the dead shark's liver.

Between May and the end of June 2017, the bodies of four white sharks—all missing their livers—washed onto South African beaches. All four deaths have been attributed to orcas. A great white’s liver is high in fat and loaded with nutrients, which may account for the orcas’ interest in singling it out for consumption. One of the sharks had its testicles and stomach missing as well.

12. DO THEY REALLY MISTAKE PEOPLE FOR SEALS? PERHAPS NOT.

Though shark-on-human attacks are rare, most of the time, when you do hear about an attack, a great white is behind it. Since 1580, Carcharodon carcharias has been positively identified in at least 314 unprovoked attacks on humans (80 of them fatal). No other shark species is credited with even half as many.

According to one common explanation, great whites attack humans because they mistake them for pinnipeds. The argument goes that, when viewed from below, a person on a surf board projects a seal-like silhouette.

While this is a popular idea, it leaves some critical things unexplained. First of all, great whites have proportionally large eyes by shark standards—and acute vision to boot. Also, the big fish strike seals with tremendous force at great speed; by comparison, the sharks usually move at a slow, deliberate pace when approaching people. And in the vast majority of attack incidents, a great white will deliver a single bite and then leave without consuming the victim. In fact, nearly three out of every four humans who get bitten by white sharks survive the encounter.

Biologists have proposed that when the animals bite people, they do so out of curiosity (at least, in most cases). “Great whites are curious and investigative animals. That’s what most people don’t understand,” marine biologist R. Aidan Martin told National Geographic. “When great whites bite something unfamiliar to them, whether a person or a crab pot, they’re looking for tactile evidence about what it is.”

The sharks often go out of their way to nibble on inanimate objects—such as underwater cameras—before losing interest and moving on. So maybe, when they decide to bite people, they're not looking for a snack.

Is There An International Standard Governing Scientific Naming Conventions?

iStock/Grafissimo
iStock/Grafissimo

Jelle Zijlstra:

There are lots of different systems of scientific names with different conventions or rules governing them: chemicals, genes, stars, archeological cultures, and so on. But the one I'm familiar with is the naming system for animals.

The modern naming system for animals derives from the works of the 18th-century Swedish naturalist Carl von Linné (Latinized to Carolus Linnaeus). Linnaeus introduced the system of binominal nomenclature, where animals have names composed of two parts, like Homo sapiens. Linnaeus wrote in Latin and most his names were of Latin origin, although a few were derived from Greek, like Rhinoceros for rhinos, or from other languages, like Sus babyrussa for the babirusa (from Malay).

Other people also started using Linnaeus's system, and a system of rules was developed and eventually codified into what is now called the International Code of Zoological Nomenclature (ICZN). In this case, therefore, there is indeed an international standard governing naming conventions. However, it does not put very strict requirements on the derivation of names: they are merely required to be in the Latin alphabet.

In practice a lot of well-known scientific names are derived from Greek. This is especially true for genus names: Tyrannosaurus, Macropus (kangaroos), Drosophila (fruit flies), Caenorhabditis (nematode worms), Peromyscus (deermice), and so on. Species names are more likely to be derived from Latin (e.g., T. rex, C. elegans, P. maniculatus, but Drosophila melanogaster is Greek again).

One interesting pattern I've noticed in mammals is that even when Linnaeus named the first genus in a group by a Latin name, usually most later names for related genera use Greek roots instead. For example, Linnaeus gave the name Mus to mice, and that is still the genus name for the house mouse, but most related genera use compounds of the Greek-derived root -mys (from μῦς), which also means "mouse." Similarly, bats for Linnaeus were Vespertilio, but there are many more compounds of the Greek root -nycteris (νυκτερίς); pigs are Sus, but compounds usually use Greek -choerus (χοῖρος) or -hys/-hyus (ὗς); weasels are Mustela but compounds usually use -gale or -galea (γαλέη); horses are Equus but compounds use -hippus (ἵππος).

This post originally appeared on Quora. Click here to view.

A Rare Blue Lobster Ended Up in a Cape Cod Restaurant

Richard wood, Flickr // CC BY 2.0
Richard wood, Flickr // CC BY 2.0

Lobsters have precious few defenses when it comes to being tossed in a vat of boiling water or on a grill and turned into dinner. They have not yet evolved into not being delicious. But sometimes, one lucky lobster can defy the odds and escape their sentence by virtue of a genetic defect that turns them blue.

According to MassLive, one such lobster has been given a reprieve at Arnold's Lobster & Clam Bar in Cape Cod, Massachusetts. Named "Baby Blue," the crustacean arrived at the restaurant from the Atlantic and was immediately singled out for its distinctive appearance.

Blue lobsters are a statistical abnormality. It's estimated only one in every two million carry the defect that creates an excessive amount of protein that results in the color. A lobsterman named Wayne Nickerson caught one in Cape Cod in 2016. He also reported catching one in 1990. Greg Ward of Rye, New Hampshire caught one near the New Hampshire and Maine border in 2017.

Lobsters can show up in a variety of colors, including orange, yellow, a mixture of orange and black, white, and even take on a two-toned appearance, with the colors split down the middle. Blue is the most common, relatively speaking. A white (albino) specimen happens in only one out of 100 million lobsters. The majority have shells with yellow, blue, and red layers and appear brown until cooked, at which point the proteins in the shell fall off to reveal the red coloring.

It's an unofficial tradition that blue lobsters aren't served up to curious customers. Instead, they're typically donated to local aquariums. Nathan Nickerson, owner Arnold's, said he plans on doing the same.

[h/t MassLive]

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