Wed 20 Jul 2016, 13:37
Which sharks hold records?
SHARK RECORD BREAKERS – Articles
1. Was “El Monstruo” actually the largest great white ever?
In 1945, an enormous white shark was caught off Cojimar, a fishing village east of Havana, Cuba. In a widely distributed photo of the shark, the entire village seems to have come out for the event. Several adults are seen in the background, while kids sit on the shark carcass, legs dangling over the side. The shark was named “El Monstruo,” meaning “the monster.”
When measured, the shark was found to be in excess of 21 feet and weighed over 7,000 pounds, which would make it the largest great white shark on record. But not all scientists trust the measurements taken that day, and the true size and weight of El Monstruo have been debated ever since.
Fishermen notoriously exaggerate the size of their catches, and so it holds that fishy stories have accompanied infamous shark landings over the years. Later analysis of the photo by experts, such as R. Aidan Martin of the ReefQuest Center for Shark Research, suggests that El Monstruo fell short of its stated size. Martin instead concluded it measured around 16 feet in length, with a weight that's hard to determine just based on a single photo.
For comparison, experts mainly agree that 20 feet is the more common maximum size for a great white, with these larger individuals weighing around 4,200 pounds. Females tend to be larger than males, so they can fall into the 20-footer group. The majority of great whites, however, measure between 13 and 16 feet with an average weight of 1,500 to 2,450 pounds.
2. The common thresher: the shark with the longest tail
And the winner for shark with the longest tail is… the thresher shark! The common thresher shark’s tail is up to 52% of its body size. These sharks are 12 to 16 feet long on average, up to a record 19 feet, meaning their tails are quite a bit longer than most people!
Threshers use their tails as weapons. When they find a school of fish they whip their tails around vigorously. When the fish are stunned and trapped, the threshers begin to eat.
These long tails can be a blessing and a curse. Although these tails are useful to threshers, they can get caught in nets and lines that are used by fishing boats to scoop up big hauls of fish. When the lines and nets are hoisted up, the threshers can hang upside down from their tails and die of suffocation. Bycatch—accidental capture of fish in nets and on lines that are after other fish—is a huge problem for all sharks, but threshers are particularly hurt by it.
3. Is the 5-inch “pocket shark” a contender for smallest shark?
There may be a brand-new contender for the smallest shark species, but it’s hard to say! For only the second time in history, scientists have located the elusive "pocket shark," named for the distinctive pocket located behind its pectoral fin (although the shark could fit in your pocket!). The specimen was located 190 miles off the shore of Louisiana during a 2010 expedition to study sperm whales.
"The pocket shark we found was only 5 and a half inches long, and was a recently born male," said NOAA's Mark Grace. "Discovering him has us thinking about where mom and dad may be, and how they got to the Gulf. The only other known specimen was found very far away, off Peru, 36 years ago."
Very little is known about the miniature creature; using tissue samples, scientists determined that the pocket shark is closely related to kite fin and cookie cutter sharks. It is believed that the shark feeds on marine mammals, squid and fishes.
4. A great white’s teeth are the largest of any living shark
The great white has the largest teeth of any extant shark species! These sharks have 300 large, triangular teeth measuring to 2 or even 2½ inches in length. Their teeth have serrated (saw-like) ridges for ripping through flesh. With one of the most powerful bites in the animal kingdom, these sharks can seemingly bite through just about anything.
The great white has not always been the gold medallist in this category, though. The teeth of the ancient Megalodon, which actually translates to “big tooth,” were much larger. Fossils show that Megalodon teeth could be up to 7 inches, with a more common size of 3 to 5 inches.
5. It’s not a race: the longest and shortest shark pregnancies
When it comes to pregnancy, some sharks don’t waste any time. The award for shortest shark pregnancy goes to the bonnethead, a type of hammerhead shark. This shark gives birth to live pups that hatch from eggs stored in the mother’s womb after only 4-½ to 5 months. Bonnetheads tend to give birth every year, in either late summer or early fall, to around 8 or 9 pups.
Other sharks are in for a very long haul. The shark with the longest pregnancy on record, the spiny dogfish, stays pregnant for two years! This is also one of the longest pregnancies of any animal – only the black alpine salamander’s is longer, at three years in cold climates. Scientists are investigating evidence that other sharks, including the frilled sharks, may be pregnant for three and a half years or more.
6. What record-breaking eyes you have, bigeye thresher
Who would have thought the bigeye thresher would have…big eyes?!
In fact, the bigeye thresher has the largest eyes of any shark – up to 7 inches high and 4 inches across. These are the biggest by proportion of any vertebrate other than birds. If a 5-foot-tall person had eyes this big, each would be 2 ½ inches wide – about the size of a tennis ball!
These eyes aren’t just for looks, either. When bigeye threshers come to the surface at night to hunt, they use their giant eyes to spot schools of fish silhouetted against the moonlight.
7. The Portuguese dogfish: diving deeper than any other shark
No shark dives deeper than the Portuguese dogfish. One was once found 12,000 feet below the surface during a study of deep-sea fish. That’s over two miles under water!
But this extreme depth is rare. These sharks spend most of their time between 1,300 and 6,500 feet, occasionally diving to around 8,900 feet in search of large, fast prey like squid and fish.
The Portuguese dogfish typically grows to about 4 feet in length, with no anal fin and two small dorsal fins. Small fins seem to be a characteristic of deep-water sharks, giving them a more standard fishlike appearance.
8. Meet Nicole, the record-setting, ocean-crossing great white shark
"Just keep swimming, just keep swimming!" A great white shark named Nicole took Dory's advice to heart in 2004, when she traversed the Indian Ocean twice, swimming from the western cost of South Africa to Western Australia – and back. Named after Nicole Kidman, the shark's 12,400-mile (20,000 kilometre) journey helped researchers better understand shark migration behaviours, which have proven important to shark conservation efforts around the globe.
The sheer distance wasn't the only remarkable aspect of Nicole's journey: researchers used the additional data gathered from the tag to plot her course, and calculated that she travelled at a minimum speed of nearly 3 miles per hour (5 kilometres per hour), making hers the fastest sustained long-distance speed recorded for a shark migration.
"This is one of the most significant discoveries about white shark ecology and suggests we might have to rewrite the life history of this powerful fish," remarked researcher Dr. Ramon Bonfil, lead author of a 2005 study about Nicole, published in the journal Science.
Nicole's journey has helped researchers re-evaluate shark conservation efforts. Although localized conservation efforts are necessary and useful, Nicole proved that the same animals protected by localized efforts frequently travel tens of thousands of miles, leaving them vulnerable in international waters.
"More studies and funding are needed to unveil the mysteries of these great predators and how they can be protected in both national and international waters," Bonfil added.
9. So many pups, so little time: the most pups in a shark litter
There are two contenders for the most shark pups in a single litter. The most shark pups recorded from a live birth was from a particularly fertile blue shark, which gave birth to 135 pups. More commonly, blue sharks will give birth to 25 to 50 pups per litter.
If you can believe it, this number more than doubles for eggs stored within a female whale shark’s body. A whale shark captured in 1966 was found to have 301 eggs! These fetal pups were found to be well-formed, averaging about 20 inches in length.
Whale shark mating and pupping behaviours have actually never been seen, and it’s difficult to draw conclusions from a single specimen. If this shark is any indication though, whale sharks are ovoviviparous, meaning the embryos develop within eggs inside the body until they’re ready to hatch. They continue to develop in the womb after hatching before they’re officially born into the world.
10. The largest shark also has the thickest skin
No shark – and in fact no living fish – is larger than a whale shark. A typical whale shark measures 18 to 32.5 feet in length. The largest on record, caught off Pakistan in 1947, was 41.5 feet in length. It weighed 28 tons – around 4 times larger than a large male elephant!
Whale sharks are not only the largest sharks in the ocean; they also have the thickest skin. Other sharks may have thick skin, but it can’t compare with a whale shark’s, which is up to 3 ½ inches thick!
Shark skin has two layers. The top layer is made up of dead cells from the bottom layer, which it protects. The bottom layer is composed of muscles, sensory nerve cells, and blood vessels.
11. Old men of the sea: Greenland sharks are the longest lived
Greenland sharks are not new to the shark scene. In fact, they are thought to be one of the longest-living vertebrates.
“Longevity is common in cold deep-sea environments," shark biologist Paul Clerkin told us. “A combination of the cold environment, large size, and slow reproduction rate has led Greenland sharks to live up to 200 years. In 1815, the average human adult life expectancy was about 40 years. A Greenland shark born at this same time could still be alive today. “
These sharks grow at an incredibly slow rate. One study found that Greenland sharks grow about 0.5 to 1 centimetre a year. And some say that female Greenland sharks may not reach sexual maturity until they reach age 100.