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News Article | November 23, 2016
Site: www.newscientist.com

Its handshake could crush your fingers. A giant crab from the Asia-Pacific region can lift the weight of a small child and has the most powerful claw strength of any crustacean. The coconut crab – Birgus latro – lives on islands in the Indian and Pacific oceans, and can reach a weight of 4 kilograms, a length of 40 centimetres and a leg span of almost a metre. Its large claws are strong enough to lift up to 28 kilograms and crack open hard coconuts – hence its name. However, the squeezing force of its claws has never been precisely measured until now. Shin-ichiro Oka at the Okinawa Churashima Foundation, Japan, and his colleagues recorded the claw strength of 29 wild coconut crabs weighing between 30 grams and 2 kilograms from Okinawa Island in southern Japan. Capturing the mighty beasts was tricky because they launched into offensive mode, says Oka. “I was pinched two times and felt eternal hell,” he says. After the researchers managed to hold the crabs down by their backs, they gave them a force sensor to squeeze. Claw strength was found to increase proportionally with body weight, and the highest reading reached almost 1800 newtons. A maximum-sized coconut crab weighing 4 kilograms could thus be expected to exert a crushing force of more than 3000 newtons, says Oka. This significantly out-muscles all other crustaceans, including lobsters, which have claw strengths of about 250 newtons. Coconut crab claws are substantially stronger than human hands, which have an average grip strength of about 300 newtons. But they cannot squeeze as hard as crocodile jaws, which bite down with a whopping 16,000 newtons – the strongest grip force known in the animal kingdom. On Okinawa Island, where there are no coconut trees, the crabs crack open nuts and hard fruit from pandanus palms. They also eat the remains of dead animals, using their claws to break the bones. Alternative names for the species include “robber crab” and “palm thief”, due to their tendency to steal food. Jakob Krieger at the University of Greifswald in Germany has studied coconut crabs on Christmas Island in the Indian Ocean, and has found that they hunt other land crab species, such as red crabs (Gecarcoidea natalis). “It makes sense in the light of the robber crab’s dietary demands to evolve strong claws,” he says. Another reason for powerful claws is defence, Oka says. The adult crabs do not have shells to shield them and instead rely on a hard, calcified outer body, which is less protective. As a result, they need their claws to ward off attackers. The crabs lead solitary lifestyles and fight aggressively with their claws if they encounter each other, probably due to competition for food. “I’ve never seen them hanging out in groups,” Oka says. Read more: Zoologger: The largest arthropod to prowl the land


News Article | February 22, 2017
Site: www.sciencenews.org

A big coconut crab snaps its outsized left claw as hard as a lion can bite, new measurements suggest. So what does a land crab the size of a small house cat do with all that pinch power? For starters, it protests having its claw-force measured, says Shin-ichiro Oka of the Okinawa Churashima Foundation in Motobu, Japan. “The coconut crab is very shy,” he says. It doesn’t attack people unprovoked. But wrangling 29 wild Birgus latro crabs on Okinawa and getting them to grip a measurement probe inspired much snapping at scientists. Oka’s hand got pinched twice (no broken bones). “Although it was just a few minutes,” he says, “I felt eternal hell.” The strongest claw grip the researchers measured squeezed with a force of about 1,765 newtons, worse than crushing a toe under the force of the full weight of a fridge. For comparison, a lion’s canines bite with 1,315 newtons and some of its molars can crunch with 2,024 newtons, a 2007 study calculated. Because grip strength increases with body size, crabs bigger than those measured in the study might surpass the bite force of most land predators, Oka and colleagues proposed last year in PLOS ONE. Coconut crabs, however, start life about as scary as a soggy grain of rice. Fertilized eggs hatch in seawater and bob around planktonlike in the western Pacific and Indian oceans. The crabs eventually return to land, where they spend most of their long lives, up to 50 (or maybe 100) years, as landlubbers that will drown if forced back into water for too long. Yet females have to risk the ocean’s edge each time they lay the next generation of eggs. Both moms and dads grow a powerful left claw, handy for dismembering whatever the omnivorous scavengers find: roadkill and other dead stuff, innards of palm trees and nuts. The crabs can break open coconuts, but the job “takes hours,” says Jakob Krieger of the University of Greifswald in Germany. Cracking open a red crab, however, takes seconds. Coconut crabs not only scavenge red crabs but also hunt them on Christmas Island in the Indian Ocean, Krieger says. Only the strictest vegetarian would ignore the 44 million or so red crabs scuttling around, and even small coconut crabs get a taste. Krieger watched an underpowered coconut crab grab hold of and wrestle its prey. The red crab abandoned its trapped limb and fled. But the little coconut crab scored a crab-leg dinner.


News Article | November 23, 2016
Site: www.csmonitor.com

You might not want to get caught in the claws of the hermit crab's big, scary cousin: the coconut crab. The enormous claws of a coconut crab may be more powerful than they look – and they look pretty scary. The crab native to islands in the Indian and Pacific Oceans can grow up to a leg-span of 3 feet and a weight of nearly 9 pounds, making it the largest terrestrial crab. Being such massive animals, coconut crabs (Birgus latro) try to eat whatever they can get their burly claws on. While that mostly means vegetation like the hard-shelled coconut for which they are named, they are also know to prey on other small animals like kittens. Anyone who has ever tried to crack open a coconut without tools knows this is quite the feat, even for a 9-pound crab. So a team of scientists decided to measure exactly how much force these hefty crustaceans can exert when they pinch their prey. As it turns out, the coconut crab's claw can pinch with a force greater than that of any other crustacean that has been measured, according to a paper published Wednesday in the journal PLOS ONE. The 9-pound crustacean could exert a force of up to 3,300 newtons, according to the new research. That's more than 4.5 times as forceful as the grip strength of most humans. As for the top land-dwelling predators, crocodiles top the crabs with bite forces of about 16,460 newtons. But the crabs come closer to hyenas, lions, and tigers, which snap their jaws shut with a force of about 4,450 newtons. (It is important to note that the coconut crabs do not snap their pinchers shut like the big cats' jaws. It's more of a crushing force than a sudden snap.) "We expected the force would be very strong. But the actual powers exceeded our expectation," study lead author Shin-ichiro Oka, a chief researcher at the Okinawa Churashima Foundation in Japan, writes in an email to The Christian Science Monitor. "And we were also surprised that their pinching force was approximately 90 times of their body weight," he says. If he himself were a coconut crab, Mr. Oka points out, at about 145 pounds, he could crush something with about 6 tons of force. So what is behind these massive pinching forces? "One of the things that crabs have is a very large concentration of muscle fibers that have a unique property, being exceptionally long sarcomeres," Graeme Taylor, a biologist at Western University in Canada who studies animal biomechanics but was not part of the coconut crab study, explains in a phone interview with the Monitor. Sarcomeres are a component in skeletal muscles that make it able to contract, so by having especially long sarcomeres, he says, "what that enables the crabs to do, in fact, is be able to produce a quite large force per unit area of muscle." Calculations suggested that coconut crabs' sarcomeres should have been particularly long for the animal's strength. But when the researchers measured the coconut crab's sarcomeres, they weren't even close to how long they should have been (although they were still significantly longer than those in species other than crabs). So the researchers say there must be other morphological characteristics behind the powerful pinchers. The researchers suggest that coconut crabs may have evolved such forceful claws as they adapted to their terrestrial lifestyle. As cousins of hermit crabs, coconut crabs start out life in a shell shelter, but as they become adults they shed the shell, and develop harder and bigger bodies. The crabs also often physically fight over resources, so such hefty claws serve as powerful weapons. "Their mighty claws also allow them to be active predators by facilitating effective hunting and feeding on other terrestrial organisms with hard exteriors, thereby aiding in the maintenance of their large body size," the researchers write in their paper. "In particular, the ability of these crabs to open coconuts demonstrates the impressive force of their claws." Approaching these crabs in the wild and getting them to clamp their claws down on force-sensing devices proved tricky. As the researchers write, "During our field study, obtaining data for analysis was challenging, as the large claws of this crab pinched us on multiple occasions." So, if you ever have to name a coconut crab, Charlie might be a good fit.


News Article | November 23, 2016
Site: www.csmonitor.com

You might not want to get caught in the claws of the hermit crab's big, scary cousin: the coconut crab. The enormous claws of a coconut crab may be more powerful than they look – and they look pretty scary. The crab native to islands in the Indian and Pacific Oceans can grow up to a leg-span of 3 feet and a weight of nearly 9 pounds, making it the largest terrestrial crab. Being such massive animals, coconut crabs (Birgus latro) try to eat whatever they can get their burly claws on. While that mostly means vegetation like the hard-shelled coconut for which they are named, they are also know to prey on other small animals like kittens. Anyone who has ever tried to crack open a coconut without tools knows this is quite the feat, even for a 9-pound crab. So a team of scientists decided to measure exactly how much force these hefty crustaceans can exert when they pinch their prey. As it turns out, the coconut crab's claw can pinch with a force greater than that of any other crustacean that has been measured, according to a paper published Wednesday in the journal PLOS ONE. The 9-pound crustacean could exert a force of up to 3,300 newtons, according to the new research. That's more than 4.5 times as forceful as the grip strength of most humans. As for the top land-dwelling predators, crocodiles top the crabs with bite forces of about 16,460 newtons. But the crabs come closer to hyenas, lions, and tigers, which snap their jaws shut with a force of about 4,450 newtons. (It is important to note that the coconut crabs do not snap their pinchers shut like the big cats' jaws. It's more of a crushing force than a sudden snap.) "We expected the force would be very strong. But the actual powers exceeded our expectation," study lead author Shin-ichiro Oka, a chief researcher at the Okinawa Churashima Foundation in Japan, writes in an email to The Christian Science Monitor. "And we were also surprised that their pinching force was approximately 90 times of their body weight," he says. If he himself were a coconut crab, Mr. Oka points out, at about 145 pounds, he could crush something with about 6 tons of force. So what is behind these massive pinching forces? "One of the things that crabs have is a very large concentration of muscle fibers that have a unique property, being exceptionally long sarcomeres," Graeme Taylor, a biologist at Western University in Canada who studies animal biomechanics but was not part of the coconut crab study, explains in a phone interview with the Monitor. Sarcomeres are a component in skeletal muscles that make it able to contract, so by having especially long sarcomeres, he says, "what that enables the crabs to do, in fact, is be able to produce a quite large force per unit area of muscle." Calculations suggested that coconut crabs' sarcomeres should have been particularly long for the animal's strength. But when the researchers measured the coconut crab's sarcomeres, they weren't even close to how long they should have been (although they were still significantly longer than those in species other than crabs). So the researchers say there must be other morphological characteristics behind the powerful pinchers. The researchers suggest that coconut crabs may have evolved such forceful claws as they adapted to their terrestrial lifestyle. As cousins of hermit crabs, coconut crabs start out life in a shell shelter, but as they become adults they shed the shell, and develop harder and bigger bodies. The crabs also often physically fight over resources, so such hefty claws serve as powerful weapons. "Their mighty claws also allow them to be active predators by facilitating effective hunting and feeding on other terrestrial organisms with hard exteriors, thereby aiding in the maintenance of their large body size," the researchers write in their paper. "In particular, the ability of these crabs to open coconuts demonstrates the impressive force of their claws." Approaching these crabs in the wild and getting them to clamp their claws down on force-sensing devices proved tricky. As the researchers write, "During our field study, obtaining data for analysis was challenging, as the large claws of this crab pinched us on multiple occasions." So, if you ever have to name a coconut crab, Charlie might be a good fit.


News Article | January 9, 2016
Site: phys.org

The great white shark of about 3.5 metres was captured and exhibited in one of the world's rare cases at a Japanese aquarium but died just after three days on January 8, 2016 A great white shark which was captured and exhibited in a Japanese aquarium, one of only a few such sharks to ever be displayed in this way, has died just after three days, the facility said Saturday. The shark, about 3.5 metres (11'5'') in length, was trapped in a fisherman's net and taken to an aquarium on the southern Japanese island of Okinawa on Tuesday. It was exhibited in the Sea of Dangerous Sharks section at Okinawa Churaumi Aquarium, but died on Friday, according to the facility. The aquarium, popular for its giant tanks where it exhibits whale sharks, said it is investigating what caused the death of the fish—of the same species as that featured in Hollywood buster "Jaws". "It is very difficult to keep great white sharks," said Keiichi Sato, an expert in cartilage fish, of the Okinawa Churashima Foundation. Two aquariums in the United States, including Monterey Bay Aquarium in California, have had the species in captive for short periods in the past, he said. "It is rare that the kind of shark is spotted in the coastal waters of Okinawa in the first place, and even if they get caught in a fisherman's net they usually die immediately because they must keep moving at high speed," Sato told AFP. "We have almost no knowledge about (the great white's) nature, so although it died we would like to share what we learnt from this experience with researchers of the world," he added. Explore further: New whale shark study used metabolomics to help understand shark and ray health


News Article | November 24, 2016
Site: www.bbc.co.uk

The claws of coconut crabs have the strongest pinching force of any crustacean, according to research. What's more, their maximum crushing force is stronger than the bite force of all land animals, except the alligator. Coconut crabs are remarkably strong, lifting up to 28 kilograms (62lb) - the weight of a small child. They use their claws to fight and defend themselves, as well as to crack open coconut shells. At up to one-metre (3 ft) across, coconut crabs are also the largest of all land-based arthropods - the group that includes insects, spiders and crustaceans. They live on small islands in the tropical Indian and Pacific oceans. Researchers in Japan measured the squeezing force of 29 wild coconut crabs living on Okinawa Island using a sensor. They calculated that a large crab could be expected to exert a squeezing force of more than 3000 newtons, which exceeds other crustaceans, such as lobsters. "The mighty claws of these crabs are useful weapons to deter predators and competitors," say scientists from the Okinawa Churashima Foundation. "In summary, coconut crabs have the ability to exert the greatest force among almost all terrestrial animals." Coconut crabs are well adapted to life on land. Unlike most crabs, they only return to the sea to lay their eggs. They can also climb trees and cut coconuts down. Despite their size and strength, little is known about coconut crabs and whether or not they are a threatened species. Charles Darwin described the coconut crab as of "monstrous size" when he saw them on the Cocos (Keeling Islands) in the Indian Ocean during the voyage of the Beagle. He wrote: "To show the wonderful strength of the front pair of pincers, I may mention that Captain Moresby confined one in a strong tin box, which had held biscuits, the lid being secured with wire; but the crab turned down the edges and escaped. "In turning down the edges it actually punched many small holes quite through the tin!"


News Article | November 24, 2016
Site: www.gizmag.com

Thanks to their tough shells, coconuts are notoriously difficult to consume – so you don't earn yourself a name like the coconut crab unless you've got a real knack for cracking them open. For the first time, scientists have quantified the force behind the mighty pincers that these creatures use in their meal preparations, finding that not only does the coconut crab have the strongest pinching force of any crustacean, its claws might match it with the jaws of most land animals, too. Coconut crabs carry quite the reputation in the world of crustaceans. As the largest among terrestrial crustaceans, they can lift up to 28 kg (61 lb) and use their beastly claws to fend off attackers, while claiming a monopoly on food sources like coconuts and other goodies with tough exteriors. Looking to gauge exactly how much force these beastly pincers can exert, researchers from Japan's Okinawa Churashima Foundation rounded up 29 wild coconut crabs from Okinawa Island, Japan, ranging in body weight, and analyzed their claws in action. The force varied from 29.4 to 1,765.2 newtons, and the scientists observed a strong positive correlation with body mass. Based on this, the team projects that the largest coconut crab, weighing 4 kg (8.2 lb), can exert a force of 3,300 newtons. This is around 10 times the average human handshake, about four times the force you'd generate when biting into a steak and about 75 percent of the force hyenas, tigers and lions generate with their jaws. Indeed, the team says it exceeds the bite force of most terrestrial animals. So if you see one, best keep your hands to yourself.


Stay safe and never try to mess with coconut crabs, Birgus latro, as their pinch will be too hard to handle. The crab with strong claws is counted as one of the strongest terrestrial animals, with a pinching power exceeded only by alligators' and some other species' bite power. According to a new study, the largest terrestrial crab has the power to pinch with a force of 750 pounds. Compare this with the moderate bite power of humans exerting just 265 pounds of force, and a trained boxer's punch may be some 770 pounds of force. Found in islands of the Pacific and Indian oceans, these crabs with powerful claws carry an upper hand in accessing foods their rivals may not get, including coconuts, of course. The pinching force of the coconut crab varies in direct proportion to the body mass. The maximum force can be 3,300 newtons based on the animals' weight. The findings came from a study by Okinawa Churashima Foundation in Japan. During the study, the researchers measured the pinching prowess of 29 wild coconut crabs on Okinawa Island. The details of the study have been published in the journal PLOS One. "We expected the force would be very strong. But the actual powers exceeded our expectation," study lead author Shin-ichiro Oka, a chief researcher at the Okinawa Churashima Foundation said. In terms of size, coconut crabs can have weight up to 4 kilograms, length up to 40 centimeters and leg span almost a meter. The study adds that the terrestrial crustacean is so strong that it can lift 28 kilograms of weight and fight enemies with claws. Since the bite varies with the weight of the animal, crabs with a range of weight were chosen. They ranged from less than one pound to 5 pounds with bites exerting 7 to 400 pounds of force (29 to 1,765 Newtons). In terms of mass, decapods had been ahead with the greatest pinch power, but no hard details on the pinching force of coconut crabs. According to scientists, the mighty claws of coconut crabs might have evolved after they ceased to have the need to carry a shell. Some 5 million years ago, this descendant from a hermit crab might have carried hard a snail shell on its back. When stripped of shells, the crabs grew larger and acquired a calcified abdomen later on. As for crocodiles, they have a super bite force of 16,460 newtons while lions, tigers, and hyenas snap jaws with a force of 4,450 newtons. Unlike big cats, coconut crabs do not snap their claws, rather applying a crushing force when they pinch. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | November 23, 2016
Site: news.yahoo.com

An Okinawa coconut crab is seen in this undated handout photo. Shin-ichiro Oka/Handout via REUTERS WASHINGTON (Reuters) - It may not be wise to get into a scrap with a coconut crab. Its claw is a mighty weapon. Scientists on Wednesday said they measured the pinch strength of this large land crab that inhabits islands in the Indian and southern Pacific oceans, calculating that its claw can exert up to an amazing 742 pounds (336.5 kg) of force. The coconut crab's pinch strength even matches or beats the bite strength of most land predators. "The pinching force of the largest coconut crab is almost equal to the bite force of adult lions," said marine biologist Shin-ichiro Oka of Japan's Okinawa Churashima Foundation, who led the research published in the journal PLOS ONE. As its name indicates, this crab eats coconuts, first using its claw to scrape away the fibrous coating and then using the claw to break it open. Its menu is larger than just coconuts.  The coconut crab also eats fruit, nuts, material fallen from trees, carrion and other crabs. In addition, after molting, it eats its own exoskeleton. It is the king of crabs and other crustaceans whose pinch strength has been assessed. "The force is remarkably strong. They can generate about 90 times their body weight," Oka added. Oka said that if he had the equivalent pinch strength per body weight of a coconut crab he could "crush something with about 6 tons of force." Its powerful claw is useful for self-defense as well as for accessing hard food sources that competitors may not be able to handle, Oka said. Coconut crabs, a type of hermit crab, are the largest land crustacean and the largest terrestrial invertebrate of any kind. They can measure up to about 3 feet (1 meter) long when their 10 legs are extended and can weigh up to about 9 pounds (4 kg). They are formidable beyond merely their pinch strength, able to lift up to about 66 pounds (30 kg). The island-dwelling species can be found as far west as Zanzibar and as far east as the Gambier Islands, with Christmas Island possessing a particularly dense population. The researchers conducted strength tests on 29 wild coconut crabs on the Japanese island of Okinawa. They are known as ornery creatures. As adults, they live alone in crevices or burrows and will attack other crabs that try to enter.It may not be wise to get into a scrap with a coconut crab. Its claw is a mighty weapon. Scientists on Wednesday said they measured the pinch strength of this large land crab that inhabits islands in the Indian and southern Pacific oceans, calculating that its claw can exert up to an amazing 742 pounds (336.5 kg) of force. The coconut crab's pinch strength even matches or beats the bite strength of most land predators. "The pinching force of the largest coconut crab is almost equal to the bite force of adult lions," said marine biologist Shin-ichiro Oka of Japan's Okinawa Churashima Foundation, who led the research published in the journal PLOS ONE. As its name indicates, this crab eats coconuts, first using its claw to scrape away the fibrous coating and then using the claw to break it open. Its menu is larger than just coconuts.  The coconut crab also eats fruit, nuts, material fallen from trees, carrion and other crabs. In addition, after molting, it eats its own exoskeleton. It is the king of crabs and other crustaceans whose pinch strength has been assessed. "The force is remarkably strong. They can generate about 90 times their body weight," Oka added. Oka said that if he had the equivalent pinch strength per body weight of a coconut crab he could "crush something with about 6 tons of force." Its powerful claw is useful for self-defense as well as for accessing hard food sources that competitors may not be able to handle, Oka said. Coconut crabs, a type of hermit crab, are the largest land crustacean and the largest terrestrial invertebrate of any kind. They can measure up to about 3 feet (1 meter) long when their 10 legs are extended and can weigh up to about 9 pounds (4 kg). They are formidable beyond merely their pinch strength, able to lift up to about 66 pounds (30 kg). The island-dwelling species can be found as far west as Zanzibar and as far east as the Gambier Islands, with Christmas Island possessing a particularly dense population. The researchers conducted strength tests on 29 wild coconut crabs on the Japanese island of Okinawa. They are known as ornery creatures. As adults, they live alone in crevices or burrows and will attack other crabs that try to enter.


News Article | November 24, 2016
Site: www.latimes.com

Coconut crabs might be the heavyweight champions of all crustaceans. The largest land-dwelling crab on Earth, Birgus latro can lift about 66 pounds with its pincers and can pinch with about 750 pounds of force. That makes the coconut crab among the strongest terrestrial animals — only alligators and a few other species have a stronger bite force. These intimidating findings come from a new study published in the journal PLOS One, in which researchers at Okinawa Churashima Foundation in Japan measured the pinching prowess of 29 coconut crabs on Okinawa Island. The crabs varied significantly in weight, ranging from less than a pound to about 5 pounds. Their pinches exerted about 7 to 400 pounds of force (or 29 to 1,765 Newtons). During the challenging process of measuring and weighing the crabs, the researchers got pinched multiple times by the animals’ claws. Since the the strength of the crabs’ claws was strongly correlated with body mass, the study authors were able to calculate the pinching force of the largest recorded coconut crab. This giant, 9-pound crustacean would have been able to pinch with about 750 pounds of force (or 3,300 Netwons). To put that in perspective, a human’s bite (from the molar) exerts an average of 265 pounds of force. And an Olympic boxer’s average punch exerts around 770 pounds of force, although this is more of a push than a clamping force. Coconut crabs, or robber crabs, may have gained their tremendous claws as they lost the need to carry a shell during the course of their evolution. These crustaceans are descended from a hermit crab ancestor which, up to about 5 million years ago, would have scavenged a hard snail shell to carry on its back for protection. Without their shells, the crabs were able to grow larger and protected themselves by developing a hard, calcified abdomen, the study suggests. (Young coconut crabs do carry a shell, but only while they’re very small). Using their super-crustacean strength, coconut crabs brandish their claws to ward off competitors and fight other animals for food and resources. But their claws aren’t just weapons, the authors wrote. The crabs are found on islands across the Pacific and Indian oceans, and their powerful pincers give them access to all kinds of foods their competitors can’t get. Their menu options include other hard-bodied animals, carrion, fruit and the fallen insides of trees. Most important, though, they use their large claws to tear through the husks of their favorite foods: coconuts. Follow me on Twitter seangreene89 and "like" Los Angeles Times Science on Facebook. Move over, elephants. Dogs have remarkable memories, researchers say Gravity signals may provide a little extra warning before an earthquake strikes A switch to daylight saving time could be lifesaving for koalas, researchers say

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