Scientists Say Greenland Sharks May Live 400 Years

NOAA, Flickr // CC BY-2.0
NOAA, Flickr // CC BY-2.0

Get ready to feel like a baby: There may be sharks alive today that are older than the United States. Like, much older. Researchers found a Greenland shark that’s around 392 years old—and 27 others with an average age of 272 years old. They published their findings today, August 11, in the journal Science. 

Young or old, Greenland sharks (Somniosus microcephalus, literally “tiny-headed sleeper”) are extraordinary creatures. They’re the second-largest carnivorous sharks in the world, reaching 2500 pounds. Their teeth are shaped and angled to remove plugs of flesh from their prey, and their own flesh is poisonous. 

Even so, Greenland sharks, like most sharks, present no risk to humans. They’re incredibly slow swimmers and live deep, deep down in the icy waters of the Arctic Ocean. These qualities make them both fascinating to scientists and tricky to track and study. And without data, it’s hard to argue that the sharks need protection.

Julius Nielsen

Previous studies had already found these sharks to have astonishingly long lives. The last estimate, based on a shark caught in 1952, concluded that they could live to be at least 200 years old. 

Science has come a long way since the 1950s, and researchers decided it was time to check again. Fortunately, they had access to a good number of Greenland sharks; unfortunately, that’s because those sharks had been accidentally caught in fishing nets and scientists’ long lines between 2010 and 2013. All 28 female sharks used in the study had been fatally injured by the time they landed onboard—some by other sharks, and some by fishing equipment—and so all were euthanized. After the sharks’ deaths, researchers measured each shark and took tissue samples from the lenses of its eyes. 

The scientists used radiocarbon dating on the samples to see if they could age the sharks. Once again, they had good data thanks to a bad situation—in this case, nuclear warfare. Scientists have known since the 1950s that nuclear bomb tests leave permanent molecular marks on sea creatures. Consequently, the appearance of bomb-related changes in an animal’s tissue can be seen as a sort of time stamp. But because these changes persist, even animals born after any given bomb can be marked by it if the animals they eat were alive during the test. 

By combining this information with the sharks’ body measurements, the scientists were able to estimate each animal’s approximate age. The youngest sharks sampled were less than 10 feet long and under 100 years old. These were mere pups for Greenland sharks; the data suggested that these animals don’t even reach sexual maturity until they’re around 150 years old. 

The oldest two sharks were 16 feet long apiece, and the scientists estimated their age at 335 (plus or minus 75 years) and 392 (plus or minus 120 years). Considering these averages, the researchers say, a conservative estimate of the shark’s longevity would put them at about 272 years old—still making them the oldest vertebrates on the planet. 

Given these astonishing findings and the threats posed to Greenland sharks by commercial fishing, the authors write, it’s time we start thinking about how to protect them.

Know of something you think we should cover? Email us at tips@mentalfloss.com.

 

11 Cute Facts About Crickets

iStock.com/sirichai_raksue
iStock.com/sirichai_raksue

They’re insects that invade our homes, but they’re beloved around the world. They’re living thermometers with ears on their knees, and they just might save the world. Here are 11 surprising (and often adorable) facts about crickets.

1. Crickets were named for the sounds they make.

The word cricket comes from the Old French word criquet, and refers to the cricket’s song—people once thought that those repeated chirps sounded like “criquet … criquet … criquet.”

Interestingly, the name for the sport of cricket has a totally different origin: it comes from an Old French word for goal post.

2. They don't make sound the way you think they do.

How do crickets chirp? Old-timey illustrators sidestepped this question by drawing them playing tiny violins. There’s a persistent myth that crickets rub their legs together to make sound. In fact, they sing with their wings.

Run your finger down the teeth of a comb and you’ll hear an almost musical rattle. Crickets make sound in a similar way. They rub a scraping organ on one wing against a comb-like organ on the other.

Each cricket species has distinctive noise-making structures that produce unique sounds. Scientists have even managed to recreate the sound of an extinct cricket relative, a fossilized Jurassic bush cricket (katydid), by examining the shape of its wings.

3. Most female crickets don't sing.

That cricket in your house that’s endlessly chirping away? It’s probably a male. Most female crickets lack those sound-making wing structures. There are exceptions: Some female mole crickets (relatives of “true” crickets) sing. And males of some cricket species never make a peep.

So why do male crickets (usually) chirp?

4. Crickets sing out of love—and anger.

It’s all about securing a mate. But crickets don’t just sing a pretty song and wait for the admirers to trickle in. Many of them have a whole repertoire of calls: There’s one for attracting females from afar, another for close-up courtship, and even a triumphal after-mating song. Crickets also sing to intimidate rival males, and some of a male’s more romantic tunes may trigger nearby females to fight each other.

5. You can use cricket songs as a thermometer.

Crickets call more frequently when the weather gets hotter. It’s such a proven phenomenon that you can use it to calculate the temperature. The snowy tree cricket’s gentle calls seem to match the heat especially accurately. The Old Farmer’s Almanac recommends that you count the number of chirps in 14 seconds and add 40 to get the temperature in Fahrenheit.

6. Some crickets have evolved to stay silent.

A particular fly species has invaded the island of Kauai in Hawaii, and it’s the stuff of cricket nightmares: It uses its incredibly sophisticated hearing system to find a singing cricket and drop maggots on it. Those maggots burrow into their victim and devour it from the inside.

Male crickets on Kauai have responded in a remarkable way. They’ve evolved wings more like a female cricket’s, which means they’ve lost the ability to chirp. Those silent, safe crickets compensate for their lack of courtship songs by spending more time on the move [PDF], which improves their chances of running into potential mates.

7. Crickets listen with their legs.

Insects have ears in weird places. Those cricket-eating parasitic flies, for example, have ears just below their head and neck. When a butterfly lands and folds up its wings, it’s exposing its ears. And cricket ears are tiny spots, just a fraction of a millimeter long, on their front legs just below the knees. They’re some of the smallest ears of any animal, but they’re highly sensitive.

8. There's a whole rainbow of crickets.

If you’ve found a cricket in your house or yard, chances are that it’s black or brownish. But that somber insect has some pretty colorful relatives. There’s the red-headed bush cricket, also known as the handsome trig—and it’s, well, pretty handsome for a cricket. The snowy tree cricket is pastel green with wings shaped like tennis rackets. And if you visit the tropics, where there are more cricket species than anywhere else, you might spot this intricately patterned Nisitrus species.

That’s just the so-called “true” crickets, members of the family Gryllidae. People also use the word cricket for many close Gryllidae relatives, and they’re an amazing bunch of insects ...

9. Crickets have rock star relatives.

One group of cricket relatives is the mole crickets. These insects have big claws and live underground. To attract mates, they throw little rock concerts: They dig horn-shaped burrows, turning their homes into amplifiers that make their calls extra loud.

Then there are the bush crickets, or katydids, which come in hot pink and other startling hues. And some katydids look so much like leaves, complete with dried patches, chew marks, and holes, that you’ve probably walked right past them without realizing you’re being watched.

Another group of cricket relatives, New Zealand’s wetas, includes enormous insects that can outweigh a mouse. The name weta comes from a Maori word for “god of ugly things.” Weta Workshop, the company that created props, costumes, and creatures for the Lord of the Rings films, took its name from these otherworldly insects.

9. People love crickets.

Insects often get a bad rap, but people of many cultures adore crickets. Chinese people have long kept these insects as good luck charms—and for cricket-on-cricket battles. Crickets are beloved in Japan, especially for their musical songs. In Brazil, some species are considered to be signs of hope or incoming wealth (though others are thought to be omens of illness and death). Charles Dickens wrote a tale called The Cricket on the Hearth that featured a cricket acting as a household’s guardian angel. And who could forget Disney’s Jiminy Cricket, and Cri-Kee from Mulan? Few other insects have received the cute Disney treatment.

10. Crickets live in our homes.

Many types of crickets will happily live in and around houses. House crickets, which are brownish and probably native to Asia, breed inside homes in many cities around the world. Black-colored field crickets will accidentally wander into buildings. And one cricket relative, the greenhouse camel cricket, has been quietly invading residences in the eastern U.S.

Fortunately, these household crickets are mostly harmless. Their poop may stain the curtains, and in rare cases they’ll nibble clothing—but usually the worst they’ll do is annoy you with their incessant calls.

11. Crickets just might save the world.

Imagine a high-protein food that’s packed with vitamins. It’s more efficient to produce than conventional meats, and it generates way less greenhouse gas. This superfood? Yup, it’s crickets. You can now purchase these insects in a variety of forms that are mercifully free of twitching legs—including flour. If westerners can overcome their squeamishness about eating insects, then crickets just may be the future of food.

This story originally ran in 2016.

Elephants Are Evolving Without Tusks Thanks to Poaching

iStock.com/LeighGregg
iStock.com/LeighGregg

Natural selection can take millions of years to shape a gene pool, but in parts of Africa, the extreme pressures of poaching may have changed elephants in just a few decades. As National Geographic reports, more tuskless elephants have emerged in regions where their ivory has made them a target.

Elephant poaching has long been in a problem Africa, but the crisis reached a fever pitch during Mozambique's 15-year civil war. Between 1977 and 1992, 90 percent of the elephants living in the country's Gorongosa National Park were slaughtered for ivory used to fund the conflict.

The diminished numbers aren't the only thing that looks different about Gorongosa's elephants today. Poachers often kill male elephants first because they have bigger tusks, and once they're eliminated, the hunters will go after females. Typically, about 2 to 4 percent of all female African elephants never develop tusks—but among female elephants that survived Mozambique's civil war, that number is 51 percent. The effects of poaching can also be observed in the next generation. Roughly 32 percent of female elephants born after 1992 are tuskless.

The trend can be seen in other parts of Africa where poaching has ravaged elephant populations. In Ruaha National Park in Tanzania, elephant behavior researcher Josephine Smit has observed that over one fifth of female elephants older than 5 years lack tusks. Tusklessness rates reach about 35 percent in females over 25.

The statistics are even harder to ignore in South Africa's Addo Elephant National Park, where tuskless animals made up 98 percent of all female elephants in the early 2000s. South Luangwa National Park in Zambia, Lupande Game Management Area in Zambia, and Queen Elizabeth National Park in Uganda each reported higher-than-average rates of tusklessness immediately following the ivory wars of the 1970s and '80s.

Though poaching is on the decline thanks to bans on the ivory trade and other conservation efforts in Africa, its impact can still be felt. In East Africa, the elephant population was nearly halved between 2008 and 2018. The establishment of wildlife preserves, DNA tracing, and GPS tracking are just a few of the ways conservationists are working to crack down on poachers and restore the species.

[h/t National Geographic]

SECTIONS

arrow
LIVE SMARTER