Tag Archives: sharks

Centuries-Old Greenland Sharks Thrive Despite Heart Disease: Secrets to Their Longevity Revealed

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Greenland shark

Greenland Sharks’ Longevity: A Closer Look at Their Heart Health

Credit: Doug Perrine/naturepl.com

Greenland sharks are believed to live between 250 to 500 years. Remarkably, even at 150 years old, they show signs of severe age-related heart disease.

Interestingly, some body parts like their eyes seem resilient to aging and cancer, suggesting that not all organs in this ocean predator are equally affected by age. Despite this resilience, research has shown that Greenland sharks (Somniosus microcephalus) do have significant heart health issues, yet they show no obvious functional decline or reduced lifespan.

Alessandro Cellerino and his team at the École Normale Supérieure in Pisa, Italy, conducted a study on six Greenland sharks (four females and two males), each exceeding 3 meters in length, and found their results to be “truly surprising.”

The researchers estimate that all six specimens were between 100 and 150 years old. They employed various advanced microscopic techniques, including high-resolution fluorescence and electron microscopy, to investigate the animals’ heart tissues.

“The hearts of Greenland sharks exhibited significant fibrotic changes and an abundance of aging markers such as lipofuscin and nitrotyrosine,” stated Cellerino.

In humans, elevated fibrosis levels in heart tissues typically signal age-related heart problems and potential heart failure.

Nevertheless, Cellerino noted that the substantial accumulation of lipofuscin, associated with mitochondrial impairment, does not appear detrimental and “does not adversely affect the lifespan of Greenland sharks.”

The high levels of nitrotyrosine, another marker associated with heart inflammation and oxidative stress, suggest that Greenland sharks may have developed a unique evolutionary strategy for enduring chronic oxidative damage, as opposed to merely attempting to avoid it.

“Initially, I thought what I observed under the microscope was a technical artifact or an error in the experiment,” he remarked.

To compare, the researchers also examined another deep-sea fish, the velvet-bellied lantern shark (Etmopterus spinax), along with the turquoise killifish (Nosobranchius furzeri), a species noted for its fleeting lifespan of mere months, residing in seasonal pools across the African savannah.

Elena Chiavatti mentioned that while the Greenland shark’s heart is highly fibrotic, the other species showed no signs of such conditions, as indicated in the Scuola Normale Superiore paper.

“The accumulation of nitrotyrosine is significant in Greenland sharks, whereas lantern sharks show no accumulation,” Chiavatti commented.

Despite their brief lifespans, killifish share similar nitrotyrosine aging markers with Greenland sharks, she added.

Cellerino emphasized that Greenland sharks exhibit extraordinary resilience to aging, particularly in their hearts. “The existence of organisms like Greenland sharks that endure aging without any noticeable heart decline is remarkable,” he noted. “These findings underscore the exceptional heart resilience of Greenland sharks and suggest potential insights into healthy aging.”

João Pedro Magalhães from the University of Birmingham highlighted that the study underscores our limited understanding of the molecular and cellular aging mechanisms, including which changes are detrimental and which are advantageous.

Furthermore, Magalhães urged for a broader variety of animals in aging and lifespan research. “Most scientists, including myself, primarily use short-lived species like earthworms, mice, and rats, but remarkable long-lived species such as Greenland sharks and bowhead whales could hold the keys to longevity,” he urged.

Source: www.newscientist.com

Killer Whales Surround Great White Sharks and Feast on Their Livers

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Killer whales execute skilled hunting techniques to bring juvenile great white sharks to the water’s surface.

Marco Villegas

Killer whales in the Gulf of California have adopted a sophisticated hunting method to target juvenile great white sharks: they turn them upside down to immobilize them. This finding implies there may be a previously unnoticed pod of orcas in the area that specialize in hunting sharks.

Only a limited number of killer whale populations are documented to consume sharks, and even fewer have been observed preying on great white sharks (carcharodon carcharius). Historically, killer whales (Orcinus orca) off the coast of San Francisco have been linked to a recorded incident involving a great white shark in 1997, and a carcass recovered near Australia revealed signs of an orca attack, documented in 2023. Until recently, only one instance of a killer whale preying on a young great white shark had been noted, and that was in South Africa.

Jesus Eric Higuera-Rivas, an independent marine biologist from Mexico, along with colleagues, captured video footage of killer whales hunting juvenile great white sharks on two occasions in the Gulf of California. The initial footage, taken in August 2020, depicted five female killer whales collaboratively pushing a juvenile great white to the surface. “The killer whale was attempting to ram the great white and flip it over,” Higuera-Rivas remarked.

This tactic induced a temporary state of paralysis in the shark, known as tonic immobility. The orcas also managed to consume the energy-rich liver of the shark, sharing it among themselves. Shortly thereafter, the pod repeated their attack on another young great white shark. In August 2022, another group of five killer whales exhibited the same hunting strategy against juvenile great whites in the identical location.

Some of the killer whales involved in the first incident were identified as those previously seen hunting whale sharks and bull sharks. However, the video from the second incident was insufficiently clear to confirm if those were the same orcas. “But it’s highly probable,” says Higuera-Rivas.

The hunting behaviors of killer whale populations differ significantly based on their habitat. “Orcas are like hunting machines, akin to snipers. They employ specific strategies tailored to their prey,” Higuera-Rivas explains. These observations indicate that the killer whales in question may be part of an unrecognized group of shark hunters.

“This provides another example of a distinct feeding strategy, likely not shared by other orca groups globally,” states Andrew Trites from the University of British Columbia, Canada. However, further research is necessary for conclusive evidence, as these killer whales might descend from Pacific Northwest populations that hunt different shark species.

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Source: www.newscientist.com

New Footage Shows How Killer Whales Outsmart Great White Sharks.

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Killer whales have increasingly been preying on dolphins in recent years. A recent report shows that now, new research indicates they have also devised a gruesome hunting strategy to target the livers of young great white sharks.

Hunting the world’s most formidable fish is no small feat, but the pod of killer whales in the Gulf of California has learned how to do it. They work together to flip the shark upside down, immobilizing it, and then extract its energy-rich liver for sharing.

Additionally, they have been captured on video executing this behavior.

Is this brutal behavior typical of killer whales? Yes, Professor Callum Roberts, a marine biologist at the University of Exeter not associated with the study, stated to BBC Science Focus.

“Orcas may be the most intelligent marine creatures, based on their innovative methods for hunting. Historically, killer whales targeted whales caught by industrial whalers and consumed their tongues.”

While killer whales have been observed preying on adult great white sharks in the past, these recent findings provide the first evidence of their strategic hunting techniques against them.

During their observations, the research team noted the pod killing not one, but two great white sharks in August 2020, and another pod consuming a third in 2022.

By pushing the shark to the surface and inverting it, the killer whales induce a state of tonic immobility in the shark due to the abrupt change in environment. In this vulnerable state, they can take what they want from the shark while leaving the rest behind.

Young sharks lack the experience to escape when a group is approaching. Researchers suggest that this implies killer whales may be hunting great whites more frequently than previously thought, as per findings in Frontiers of Marine Science.

“I believe that killer whales that target elasmobranchs (sharks and rays) are capable of finding great whites whenever they choose,” said the study’s lead author, Eric Higuera Rivas.

“This behavior showcases the killer whales’ intelligence, strategic mindset, and advanced social learning, with hunting techniques evolving and being shared across generations within their pods.”







Climate change may play a significant role in this behavior. The intensification of the El Niño phenomenon, which results from warming in the Pacific Ocean, is expanding the habitat of great white sharks into killer whale territories. These regions are populated with young, inexperienced sharks, making them easy targets.

Experts worry that this behavior could be detrimental for the shark population.

“What benefits killer whales might not bode well for sharks. Both species are endangered,” Roberts noted. “Let’s hope they don’t spread these hunting strategies too widely.”

About our experts

Callum Roberts serves as Professor of Marine Conservation at the University of Exeter and previously held the position of Chief Scientific Advisor for BBC One. He has authored several books, including the “Blue Planet II” series and Oceans of Life: How our oceans are changing (Penguin Books, £22) and Coral Reef Life (Profile Book, £12.99).

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Source: www.sciencefocus.com

Video Captures Orcas Preying on Great White Sharks and Consuming Their Livers

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Certain killer whales have a preference for liver, particularly that of great white sharks.

A video captured by Mexican scientists demonstrates how an astute whale targets the apex predator’s fatty organs.

Researchers documented two killer whale hunts in the Gulf of California, one in 2020 and the other in 2022. The footage reveals a group of great white sharks flipping a young shark onto its back, disorienting it, before slicing open its side to extract its liver. The findings from this video study were published on Monday in Frontiers in Marine Science.

In one notable scene, all members of the shark clan feasted on the pink liver fat while the remainder of the shark’s body remained submerged in the ocean depths. A sea lion was seen lurking nearby, seemingly hoping to steal a meal, but orcas released bubbles to ward it off.

Marine biologist and documentarian Eric Higuera Rivas, who filmed the hunt from a nearby boat, initially did not grasp the significance of the footage until he began editing.

“On the monitor, we noticed the shark’s liver hanging out, already dislodged. Moments later, the shark emerged with the liver in its mouth,” recounted Higuera Rivas, a co-author of the study. “I was astonished to learn it was a great white shark. I could hardly believe it.”

Heather Bowlby, a researcher from Fisheries and Oceans Canada not involved in the study, noted that the footage serves as a strong reminder that even apex predators need to stay vigilant.

“We typically view great white sharks as the pinnacle of the food chain,” she stated. “It’s always beneficial to remind them that they can also be prey.”

Higuera Rivas and his team indicated that the hunt appeared to involve members of the same group of killer whales, which they have designated as Moctezuma pods. This pod regularly patrols the Baja California coast, primarily hunting elasmobranchs, including sharks and whales. Higuera Rivas has been monitoring these pods and recording their behaviors for over a decade, noting their adaptations based on the species they target.

Previously, evidence of killer whales preying on great white sharks was limited to South Africa, where they have been known to extract livers and wash the remains ashore.

Alison Towner, a marine biologist at Rhodes University specializing in the South African phenomenon, stated that while behaviors in Mexico and South Africa are similar, they are not identical; Mexican killer whales typically target younger sharks, whereas their South African counterparts focus on adults.

Towner indicated that individual killer whale pods likely learned their hunting strategies independently.

“Observing this behavior in Mexico implies that specific groups of killer whales have developed distinct methods for hunting sharks,” she mentioned via email. “Even though the same organs are the target, the manner in which they are approached varies from what we have documented in South Africa, indicating group-specific learning.”

A new study reveals that Mexican killer whales have discovered a vulnerability in great white sharks.

“When flipped over, a shark enters a state known as tonic immobility,” explained study co-author Francesca Pancaldi, a shark researcher at the National Institute of Marine Sciences. “They become immobilized, akin to a catatonic state. They simply freeze.”

The liver, a nutrient-rich and fatty organ, comprises about a quarter of a shark’s body, delivering “a substantial amount of energy,” he added.

Researchers from both South Africa and Mexico concurred that this hunting behavior is likely not new to killer whales. What has changed for scientists is the advancement of drone technology, which has enhanced the ability to observe and document these hunting events.

“I believe this has been occurring for centuries, but it’s challenging to witness such events,” Pancaldi remarked.

However, she also mentioned that climate changes may have heightened interactions between great white sharks and the octopus pods.

“In fact, we have noticed a growing presence of great white sharks in the Gulf of California over the past decade,” Pancaldi noted, explaining that the species is particularly sensitive to changes in ocean temperatures linked to weather patterns such as El Niño.

According to Towner, scientists in South Africa began observing attacks by killer whales on great white sharks nearly a decade ago. Such predatory behavior has caused great whites to abandon their usual feeding, resting, and breeding spots, referred to as assemblages.

“As a result of repeated predation, great whites have entirely vacated their traditional core gathering sites,” Towner explained. “Many sharks may have relocated offshore or to less monitored regions, which is reshaping coastal ecosystems.”

Following the exodus of the sharks, populations of Cape fur seals and sevengill sharks have surged, leading to conflicts with the primary prey species, such as small fish and smaller sharks, according to the report. This study was published in Frontiers in Marine Science earlier this year.

Mr. Towner noted that only two adult male killer whales, referred to as Port and Starboard, were responsible for the frequent attacks on great white sharks in South Africa. This predation puts pressure on great whites, which have slow growth and reproductive rates, and a similar situation could develop in Mexico if this behavior becomes more prevalent.

Source: www.nbcnews.com

Rare Footage Reveals Sharks Feeding in Unison

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This exceptional footage captures a large group of sharks calmly feeding on decaying corpses off the coast of Hawaii.

The marine White Tip and Tiger sharks displayed no aggressive behavior toward one another or the film crew, and they shared the bloated remains with ease.

Marine biologists at the University of Hawaii Manoa conducted a study on this event, publishing their findings in the Science Journal Frontier of Fish Science.

First Author Dr. Molly Scott stated, “To our knowledge, this is the first study documenting the feeding aggregation of tiger sharks and marine white tip sharks.”

“These species are seldom seen together in the wild due to their vastly different habitats.”

https://c02.purpledshub.com/uploads/sites/41/2025/05/New-Shark-Vid-1.m4v
While most sharks hunt for their food, cleaning can also serve as an important food source.

Ocean white tips can grow to lengths of up to 2 meters and are threatened by roaming sharks, although they occasionally visit Hawaii’s Oshima during the spring and summer.

In contrast, tiger sharks can reach lengths of 4 meters and are more coastal, preferring to stay in the same area throughout the year.

According to Scott, witnessing these two species in the same location is “incredibly rare,” especially as they shared the food with no conflict.

“We observed up to 12 small individual sharks feeding intermittently on very decomposed corpses, and we saw no aggressive behavior, whether interspecific or intraspecies,” she noted.

“This amazed me. I expected some aggressiveness when multiple sharks were feeding around these small corpses, but it appeared that each shark understood its role in the social hierarchy.”

https://c02.purpledshub.com/uploads/sites/41/2025/05/New-Shark-Vid-2.m4v
A larger shark approached and bit the body directly, while a smaller shark consumed a floating piece.

It appears that the social order allowed the larger sharks to feed first, except that smaller female tiger sharks tended to dominate the two largest marine white tips.

“Some individuals, like female tiger sharks, may have been either shy or bold about their size,” Scott explained. “They might not have been welcomed to join in, as the feeding order was already established before they arrived.”

The smallest sharks remained just beneath the surface, snacking on scraps.

While all these sharks are primarily hunters, they may engage in cleaning when opportunities arise, such as when they detect a body.

https://c02.purpledshub.com/uploads/sites/41/2025/05/New-Shark-Vid-3.m4v
The observations continued for over eight hours, and by the next day, the body was gone.

The floating carcass was first spotted in April 2024 by a tourist boat about 10 km off the west coast of Big Island.

The observed feeding lasted 8.5 hours, with at least nine marine white tip sharks and five tiger sharks participating, while a few individuals were in the water the whole time.

“None of the photographers reported any frightening, aggressive, or harmful interactions with the sharks,” Scott remarked. “I hope this presents a new perspective that sharks are not the mindless predators they are often portrayed to be.”

Researchers also aim for this unusual observation to deepen the understanding of shark behavior, particularly their interactions with one another.

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Source: www.sciencefocus.com

New Research Uncovers Opportunistic Hyperdevelopment in Megatooth Sharks

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In a study published today in the journal Earth and Planetary Science Letters, paleontologists examined the ratio of two distinct zinc isotopes in the enamel of 19 dental species from early Miocene marine ecosystems, including the Megatooth Sharks Otodus Megalodon and Otodus chubutensis.

Otodus Megalodon became extinct 3.6 million years ago. Image credit: Alex Boersma/PNAS.” width=”580″ height=”421″ srcset=”https://cdn.sci.news/images/2023/06/image_12042-Otodus-megalodon.jpg 580w, https://cdn.sci.news/images/2023/06/image_12042-Otodus-megalodon-300×218.jpg 300w, https://cdn.sci.news/images/2023/06/image_12042-Otodus-megalodon-104×75.jpg 104w” sizes=”(max-width: 580px) 100vw, 580px”/>

Otodus Megalodon became extinct 3.6 million years ago. Image credit: Alex Boersma/PNAS.

Otodus Megalodon was a colossal megatooth shark that inhabited the world’s oceans from 23 to 3.6 million years ago.

It could reach a length of at least 15 meters, making it one of the largest apex marine predators since the Mesozoic Era.

“Otodus Megalodon,” stated Dr. Jeremy McCormack from Goethe University in Frankfurt, “was estimated to require about 100,000 calories per day.”

“Scientists have generally believed that megalodon primarily consumed whales.”

“At least, that’s what it depended on if whales were available for extended periods.”

“However, it seems that Megalodon had a much broader range of prey than previously thought.”

In the recent study, Dr. McCormack and his colleagues investigated the ratio of zinc-64 and zinc-66 isotopes in the dental enamel of 19 fossil species from sediments that are 20.4 to 16 million years old, discovered in the shallow waters of the Burdigalian seaways in what is now southern Germany.

“Zinc is ingested through food, which means the heavier zinc-66 is stored in muscles and organs,” they explained.

“As a result, fish that consume other fish accumulate a high amount of zinc-66. Therefore, those that eat them will have even less.”

“This is why Otodus Megalodon and its relative Otodus chubutensis exhibited the lowest ratios of zinc-66 to zinc-64 at the top of the food chain.”

“Seabreams that fed on mussels, snails, and crustaceans represented the lowest level of our food chain study,” Dr. McCormack noted.

“Following that were smaller shark species, including Requiem sharks, and the ancestors of modern whales, dolphins, and porpoises.”

“Larger sharks, such as sand tiger sharks, occupied higher levels of the food pyramid, with immense sharks like Aralosera coscuspidatus and Otodus sharks containing Megalodon at the top.”

“However, Otodus sharks cannot be distinctly differentiated from lower levels of the pyramid.”

“Megalodons were versatile enough to consume marine mammals and large fish, depending on their availability from both the upper and lower tiers of the food pyramid.”

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Jeremy McCormack et al. The vegetative ecology of Miocene marine vertebrates reveals the Megatooth Shark as an opportunistic hypercarnivore. Earth and Planetary Science Letters Published online on May 26, 2025. doi:10.1016/j.epsl.2025.119392

Source: www.sci.news

How Greenland Sharks Survive for Centuries Without Going Blind

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                <img class="Image" alt="" width="1350" height="899" src="https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg" sizes="(min-width: 1288px) 837px, (min-width: 1024px) calc(57.5vw + 55px), (min-width: 415px) calc(100vw - 40px), calc(70vw + 74px)" srcset="https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=300 300w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=400 400w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=500 500w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=600 600w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=700 700w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=800 800w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=837 837w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=900 900w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1003 1003w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1100 1100w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1200 1200w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1300 1300w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1400 1400w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1500 1500w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1600 1600w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1674 1674w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1700 1700w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1800 1800w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=1900 1900w, https://images.newscientist.com/wp-content/uploads/2025/04/30143613/SEI_249430623.jpg?width=2006 2006w" loading="eager" fetchpriority="high" data-image-context="Article" data-image-id="2478629" data-caption="Greenland sharks’ eyes don’t seem to deteriorate with age" data-credit="WaterFrame/Alamy"/>
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                    <p class="ArticleImageCaption__Title">Greenland shark eyes appear to retain their integrity over time</p>
                    <p class="ArticleImageCaption__Credit">Water Frame/Alamy</p>
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    <p>The Greenland shark, the longest-living vertebrate on the planet, exhibits no signs of retinal degeneration despite surviving for centuries. This discovery has intrigued scientists, particularly as these creatures are thought to be functionally blind, inhabiting the bleak depths of the ocean.</p>
    <p><a href="https://duw.unibas.ch/en/persons/fogg-lily/">Lily Fog</a> from the University of Basel, Switzerland, and her team performed a detailed examination of the eyes of eight deceased Greenland sharks (<em>Somniosus microcephalus</em>) and analyzed their DNA.</p>
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Source: www.newscientist.com

The sharks never stay quiet

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Hound Shark Species Mustelus lenticulatus

Paul Kaiger

At least one shark species has bark that can be chewed. Scientists report that clicks can be made.

During his doctoral studies at the University of Auckland, New Zealand, Carolyn NeederHe was currently studying shark hearing at Woods Hole Marine Facility in Massachusetts. When dealing with sharks during the experiment, she noticed one species – a hound (a rig called a rig)Mustelus lenticulatus) – It looked like it was making a metallic click.

“The sharks weren’t supposed to make noise, so I ignored it,” Nieder says. “And that was just happening.”

The ability to intentionally produce sounds is common among terrestrial animals, as the world full of bird verticals and mammalian plagues shows. However, underwater, many fish make noises by shaving objects or vibrating muscles, and in 2022 researchers reported that relatives near sharks can sometimes click when divers interfere. The shark sounds had not yet been officially explained.

To confirm the presence of the rig’s noise, Nieder and her colleagues brought 10 boys rigs into the lab, caught up in the waters of New Zealand’s North Island. There, they were placed in the tank with sensitive sound recording instruments. The team gently handled the sharks and found that all of them were clicking accordingly. Rigs seem to be the first shark known to produce sounds that are not associated with other actions, such as feeding or bumping into something.

Researchers believe that sharks may be producing sounds by snapping their jaws together. Just like click rays, the rig flattens the teeth, which can produce sharp sounds on the impact. Please listen to the following:


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Further research may check whether the cause of clicks and whether there is a feature. Nieder points out that because rigs are small sharks and potential prey for large animals, clicks can play a role in defense when animals are bitten or gripped.

“It could be a bit confusing for predators,” she says. It is also possible that clicks play a role in hunting, she adds, including scaring and inclusive shark crustacean prey.

Rig shark teeth

Eric Palmentier

“This has been seen for a long time, but is a potentially very important area of ​​shark biology,” he says. Aaron Rice He was not involved in research at Cornell University in New York.

When healthy production is widespread among sharks, their clicks may help them study populations that often decline rapidly, says Rice. He says there is a very rich sound data recorded from fish and whale studies, and it is possible that they also shot shark sounds. These can be used to determine if a shark is in the area and add another tool to monitor at-risk predators.

“[The finding] It represents something truly new and new discoveries in basic biology,” says Rice.

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Source: www.newscientist.com

One simple reason why baby sharks are are more frightening than adorable

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When it comes to cuteness, it’s all subjective. Depending on the species, baby sharks can be as small as palm-sized infants like small spotted cat sharks that hatch from “mermaid's purse” egg cases or directly from their mothers as long-bodied pups with outstretched arms.

This is especially true for sand tiger sharks, although it’s surprising how these tiny creatures grow so big. Sand tiger sharks are one of the many species where fertilized eggs hatch inside the female’s body and develop in the womb.

It’s quite common for shark fetuses to feed on unfertilized eggs, a behavior seen in over a dozen species. Sandwich shark embryos are even more developed, with ultrasound scans showing them swimming between the uterus prongs, likely searching for more sustenance.

After a year of gestation, female sand tiger sharks give birth to one or two large pups, considered the survivors of a fierce intrauterine battle. While their size at birth helps protect them from many predators, they are also at risk of getting caught in fishing nets, pushing them closer to extinction.

Researchers studied shark carcasses caught in nets across South Africa to understand why unborn sand tiger sharks engage in cannibalism. They found that females carrying more advanced embryos produced fewer fetuses due to intrauterine competition.

DNA testing revealed that sand tiger shark fetuses are born to multiple fathers in a litter, showing a complex mating system where the offspring of one dominant male tend to outcompete their half-siblings.

It’s unclear why this occurs, but it could be a strategy for females to select the best mate or for the strongest sperm to produce the most viable offspring. This article dives into the intriguing world of baby sharks and their complex familial relationships.

This article addresses questions like: “How cute are baby sharks in real life?” – Jacob Barnett, Peterborough

For inquiries, contact us at: questions@sciencefocus.com or message us on Facebook, Twitter, or Instagram (remember to include your name and location).

Explore more fun facts and fascinating science topics on our ultimate science pages.

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Source: www.sciencefocus.com

Evidence shows pregnant sharks are preyed on by larger sharks

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Prior to giving birth, the pregnant porbeagle shark was expected to give birth soon, when one of the two tracking tags attached to the shark by marine scientists resurfaced near Bermuda.

Surprisingly, the tag emerged much earlier than anticipated. It had been affixed to the 7-foot-long shark only 158 days prior, after conducting an ultrasound scan off the coast of Cape Cod, Massachusetts, in October 2020. The tag was supposed to remain attached for about a year.

“Something seemed amiss,” stated Brooke Anderson, a shark researcher at Arizona State University during that time.

The second tag, which was designed to transmit a signal when the shark’s fin breached the surface, never sent a signal again.

Data collected from the retrieved “pop-off” tag revealed an unusual pattern: for the initial five months, the depth and temperature information appeared normal for this species, but then deviations started to occur.

“Unexpectedly, temperatures suddenly spiked and remained high even at depths of 600 meters,” recounted Anderson.

The diving patterns of the creatures also became peculiar.

Of the 11 porbeagle sharks that researchers tagged, eight were pregnant, including this one.
John Dodd

“All the data pointed in one direction: she had been consumed,” remarked Anderson.

The researchers ascertained that the irregular readings from the tag were due to it having been inside another animal’s stomach for several days.

Their conclusions were detailed in a study published in the Frontiers in Marine Science journal, shedding light on the fact that porbeagle sharks are being preyed upon by much bigger animals.

Naming a few possible predators, the researchers narrowed down their suspects based on biological characteristics – the data didn’t align with a mammal like a killer whale, leading them to focus on warm-blooded sharks with some heat-generating capacity.

“The predator needed to elevate its body temperature above the ambient water, have the size to inflict damage on the porbeagle, and reside in the area of the predation,” explained Anderson.

The researchers inferred that a great white shark or mako shark likely devoured the pregnant porbeagle, temporarily swallowing the tag.

“Our estimation is that it was a mature female great white shark, possibly exceeding 15 feet in length,” disclosed Anderson.

Previously, the notion that porbeagle sharks might fall prey to larger creatures had not been considered, she added.

Originally, their team aimed to track pregnant porbeagle sharks during their gestation period and pinpoint where they typically give birth.

Across two Atlantic seasons, they located and tagged a total of 11 porbeagle sharks, hauling each one onto the boat, treating them with aerated seawater, and concealing their eyes with wet towels.

“We operated like a NASCAR pit crew,” described Anderson. Eight of these sharks were pregnant.

Their expectations didn’t encompass uncovering a profound deep-sea mystery.

Matt Davis, a marine resources scientist from the Maine Department of Marine Resources not involved in the research, acknowledged that the study’s conclusions were plausible.

This incident underscores the continued need for scientific exploration of mid-depth ocean life and predator-prey interactions, added Davis.

The porbeagle shark is categorized as an endangered species by the International Union for Conservation of Nature. Overfishing activities began in the 1960s, causing a population decline of 75 to 80 percent by 2001, as per Anderson.

While the species is recuperating due to fishing regulations, their longer lifespan and lower reproductive rate mean a protracted recovery process.

“We must continue tagging and monitoring these sharks to understand the frequency of such incidents,” emphasized Anderson regarding the predation. “In an instant, this critically endangered species lost not just its essential breeding females, but all its developing offspring as well. It is crucial to grasp both the frequency and impact of such events.”

Their research could play a pivotal role in restoring a healthy shark population in the Atlantic, where sharks prey on sharks.

Source: www.nbcnews.com

Paleontologists say that crocodiles and tiger sharks preyed on Miocene dugongs

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Paleontologists have unearthed the 20-million-year-old fossil skeleton of a species of sirenian mammal from the dugong family. Cleavage Shark and crocodile bite marks have been found in northwestern Venezuela. The most prominent bite marks are from deep, dragging tooth impacts concentrated on the snout of the animals. Researchers interpret this as the result of active predation, as they are similar to bite marks made by crocodiles when they grab and roll their prey. Moreover, shark bite marks can be observed throughout Venezuela. CleavageThe skeleton of Tiger shark (Galeocerdo Aduncus) The teeth associated with this skeleton.

Tiger sharks are congregating to make easy catches of larger prey as crocodiles attack ancient dugong-like siren mammals. CleavageImage courtesy of Jaime Bran Sarmiento.

“Our discovery adds to the growing evidence that food chains millions of years ago worked in a similar way to how they do today,” said Dr Aldo Benitez Palomino, a paleontologist at the institute. University of Zurich.

“Today, when we observe predators in the wild, we often find dead prey, indicating that the animal also served as a food source for other animals. However, the fossil record of this is rare.”

“It was unclear which animals would serve this purpose as a food source for multiple predators.”

“Our previous research has confirmed that several shark species scavenge sperm whale carcasses, and this new study highlights the importance of sea cows in the food chain.”

Evidence for food web interactions is abundant in the fossil record, but most of it is represented by fragmentary fossils that provide ambiguous meaning.

Therefore, it is often difficult to distinguish between active feeding and signs of saprophytic activity.

“Our results are one of the few to document multiple predators on a single prey and provide a glimpse into food webs in the region during the Miocene,” Dr Benitez-Palomino said.

The dugong specimen studied by the team was collected from an outcrop of the Agua Clara Formation, south of the city of Coro, Venezuela.

The fossil is closely related to a species of sirenian in the dugong family. Cleavage.

“We first heard about the site through word of mouth from local farmers who noticed some unusual 'rocks'. We were intrigued and decided to investigate,” said Professor Marcelo Sánchez-Vilagra from the University of Zurich.

“Initially, we weren't familiar with the geology of the site, and the first fossil we unearthed was just part of a skull.”

“It took us a while to identify what it was – very strange looking remains of a sea cow.”

“By studying geological maps and examining the sediments at the new site, we were able to determine the age of the rocks in which the fossils were found.”

“One of the factors that allowed us to observe evidence of aquatic mammal predation, which is known to exist in this region, is the extremely well-preserved cortical layer of the fossil, which is likely due to the fine sediment in which the fossil was embedded.”

“After locating the fossils, our team organized a paleontological rescue operation, employing extraction techniques with full case protection.”

“A team of five people was involved in working on the fossil, and the job took about seven hours.”

“The subsequent preparations, particularly the meticulous task of preparing and repairing the skull, took several months.”

Team Survey results Published in Journal of Vertebrate Paleontology.

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Aldo Benitez Palomino othersTrophic interactions between sharks and crocodiles and Sirenia in the Miocene of Venezuela. Journal of Vertebrate Paleontologyy, published online August 28, 2024, doi: 10.1080/02724634.2024.2381505

Source: www.sci.news

The Dangers of Deadly Cold Water Gush for Migratory Sharks

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Bull sharks may be vulnerable to cold upwelling

Martin Prohaskatz/Shutterstock

The upwelling of cold water from the deep ocean to the surface can be deadly to marine animals, and such events are becoming more frequent due to climate change.

In March 2021, hundreds of dead seafood, squid, octopus, manta rays, and bull sharks washed up on South African beaches.

The animals were fleeing high water temperatures from a marine heatwave hitting South Africa's coastal waters.

However, during their escape, they were caught in a sudden burst of cold water from the region's Agulhas Current, causing ocean temperatures to plummet.

“These upwelling events occurring on the banks of the Agulhas River could cause temperatures to suddenly drop by about 10 degrees Celsius.” [18°F] “within 24 hours” Zoe Jacobs At the UK National Marine Centre. “This is a very intense, short-term event.”

Nicholas Lubitz Professors at Australia's James Cook University used 41 years of sea surface temperature data and 33 years of sea surface temperature data to assess cold water upwelling in two regions affected by the Agulhas Current and the Australian Current, which meanders along Australia's east coast. I studied wind records.

They conclude that stronger ocean currents and changes in wind patterns associated with climate change are increasing both the frequency and strength of cold water upwelling in both regions.

Most marine organisms that live near these currents are adapted to sudden fluctuations in water temperature and can therefore cope with these changes.

However, the study warns that migratory species such as bull sharks, which pass through these waters and are unprepared for sudden changes in temperature, are at risk.

Bull sharks struggle to survive when water temperatures drop below 19°C (66°F) for extended periods. Lubitz and colleagues used data from 41 tagged bull sharks in southern Africa and Australia to study their migration patterns.

As soon as summer ends and water temperatures begin to drop, sharks migrate to warmer tropical waters. During migration, they appear to take steps to avoid cold water upwelling by moving to warmer surface waters as they swim through upwelling zones, or by seeking refuge in estuaries and bays during migration. .

But as upwelling events increase in frequency and intensity, researchers warn that it will become increasingly difficult for bull sharks and other migratory species to avoid them.

But Jacobs, who was not involved in the study, said the effects may be limited to the two areas studied. “These two particular regions of hers are very special cases because the upwelling that occurs there is a very short and intense phenomenon,” she says. Other global upwelling systems are more permanent or seasonal, and marine species are better adapted to withstand or avoid changes in water temperature, she says.

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Source: www.newscientist.com

New Study Claims Megalodon Sharks Were Not as Powerful as Previously Believed

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A recent study suggests that the megalodon’s body shape might not have been as chunky as previously thought. Contrary to popular belief, researchers now suspect that this prehistoric fish, also known as the megalodon (Otodus megalodon), may have had a more elongated form, akin to modern slim sharks.

The typical estimation of the megalodon’s length is between 15 to 20 meters (50 to 65 feet), and they inhabited the earth’s oceans from 15 million to 3.6 million years ago. However, the fossil record contains limited evidence of the megalodon, mainly consisting of teeth and vertebrae rather than intact skeletons.

While previous estimates of its body size were based on the bodies of contemporary great white sharks (Carcharodon carcharius), resulting in the assumption of a thick and round body shape, a new study published in the Old Trogia Electronica journal suggests that the megalodon was more than just a larger version of the great white shark. The study contends that the animal may have had similarities to the slimmer modern mako shark.

So what’s the controversy?

Essentially, two groups of scientists are at odds over the actual size and shape of the megalodon.

A study led by scientists from DePaul University and the University of California, Riverside (UCR) employed a CT scanner on a live great white shark to compare its vertebral skeleton to existing reconstructions of the megalodon’s spinal column. This study suggests significant enough differences between the two sharks to propose that the megalodon was not merely a larger great white shark.

However, a UK-based research team utilized advanced 3D modeling to study the body structures of various shark species, including great whites, mako sharks, and salmon sharks. With this approach, they concluded that the megalodon may have been even larger than previously anticipated, with a dorsal fin comparable in size to an adult’s height.

The earlier study’s authors critiqued the new findings, asserting that they rely on circular logic and lack statistical validation. They also mentioned the absence of raw data for future researchers to verify or reproduce the study’s results. Their study was peer-reviewed by prominent shark experts from around the world, although not by the authors of the new study.

Yeah, but…can Jason Statham still defeat Megalodon?

Regardless of the megalodon’s shape, the lifespan and dietary habits of this extinct shark remain unclear. To further advance their understanding, researchers will need to find a complete or near-complete skeleton. The potential elongated body of the megalodon, if confirmed, could prompt a reassessment of its life, diet, and extinction causes.

As for the debate over the megalodon’s size and shape, the fact that it was a large, formidable predator is indisputable. However, the question of whether Jason Statham could defeat it in battle remains up for discussion.

“Even with the interpretation of the megalodon’s shape as more slender, I don’t think the odds for that matchup will change significantly,” Cooper stated. “Regardless of which theory you favor, whether the shark was fat or skinny, the short answer is that megalodon was still a very large shark. Either way, it’s a massive challenge for Statham.”

About our experts

Jack Cooper is a postdoctoral researcher in palaeontology at Swansea University. His research covers scientific report, scientific progress and the Fish Biology Journal.

Professor Catalina Pimiento is a Senior Lecturer in Paleontology at Swansea University. Her research specializes in Frontiers of ecology and evolution, natural ecology and evolution, and scientific progress.

Professor John Hutchinson is Professor of Evolutionary Biomechanics at the Royal Veterinary College. His research spans nature communications, anatomy journal, and scientific progress.

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Source: www.sciencefocus.com

Preventing Sharks from entering the beach through Catch and Release methods.

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Scarred great white shark sails through Australian waters

Philip Thurston/Getty Images

Great white sharks avoid areas where they are captured, so this could be a way to deter them from hunting near swimmers.

They say it's a flight response. paul butcher In the New South Wales Department of Primary Industries, Australia. “It's the same with almost any animal, and it's the same with sharks.” The animals then “resume normal locomotor behavior as if nothing happened,” he says.

Butcher and his colleagues use smart (Real Time Shark Management Alerts) Drumlines: Baited hooks attached to buoys 500 meters off the coast in approximately 20 popular areas of New South Wales. Each of the 305 drumlines in total is equipped with a system to notify local response teams, which she aims to reach by boat within 30 minutes of a hooked shark feeding. Lines are set up fresh each morning and collected the same day, so they are never left overnight.

The team records the shark's size and health and tags it. Sharks considered to be more of a threat to swimmers, such as great whites, tiger sharks and bull sharks, are then moved 500 meters offshore and released. Other species, such as hammerhead sharks and gray nurse sharks, are released where they are captured.

Butcher and his colleagues monitored 36 great white sharks (carcharodon carcharius) had a satellite-linked radio-transmitting tag attached to its dorsal fin after being captured in five locations in 2016. During the first 3 days after release, all sharks moved away from the shoreline where they were captured and mostly stayed there. offshore.

“Ten days after release, sharks gradually moved closer to shore, but 77% of sharks remained more than 1.9 kilometers from shore, with an average of 5 kilometers from their tagged location,” the study said. they wrote in their paper.

Additionally, sharks are still being detected by tracking devices an average of nearly 600 days after release, indicating that the program is not increasing the risk of shark mortality.

Since 2015, more than 1,100 great white sharks, with an average length of about 7 feet, have been captured on SMART drumlines and more than 400 capture events have taken place, Butcher said.

The drumline is part of a larger effort in New South Wales to find non-lethal ways to keep great white, tiger and bull sharks away from people in the water. Drones are currently flying over up to 50 beaches to monitor for sharks and other potential threats during the school holidays, with the department using tagged sharks to detect when they pass nearby. It operates 37 listening station buoys. This information is transmitted to the public via: SharkSmart app.

This suite of tools could mean one day the controversial beach nets that captured 228 animals in New South Wales alone during the 2022/23 reporting period can be removed. Of these 228 animals, only 85 were released alive, and more than 200 were non-target species such as turtles, dolphins and seals.

david booth Researchers at the University of Technology Sydney say the findings are very good news. “And being able to see the captured and released animals again after so many years is very moving and certainly better than slaughtering them,” he says.

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Source: www.newscientist.com

Newly Discovered Resting Behavior of Gray Reef Sharks Will Surprise You

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Considered to be a perpetually mobile predator, gray reef sharks have only ever been observed in motion, leading many to believe that they need to swim to breathe. Credit: © Christopher Leon

The first report of a gray shark resting under a reef shelf in the Seychelles changes our knowledge of how they breathe (they don’t need to keep swimming to stay alive), and the science of sleeping sharks. The basis for this has been clarified again.

A predator in perpetual motion. I can’t sleep in our ocean. If you have this impression of sharks, you’re not alone. There’s a good reason for that. Sharks have to swim to breathe (that’s what we were told). The science of shark sleep and breathing is related, and all sharks use gills for breathing, but he has two ways to move oxygen-rich seawater over the gills.

Some sharks, called obligatory rams, “ram” oxygen-rich seawater over their gills, which requires them to keep moving.other seedThey actively pump seawater over their gills while at rest, called buccal pumps.

Evidence of shark rest: A new perspective

Today’s science shows that sharks may be stationary, and there are also suggestions that sharks are asleep. However, there is no solid evidence regarding the sleep behavior of Ram ventilators. Scientists hypothesize that they may not be sleeping at all, sleeping using half their brains (like sperm whales and bottlenose dolphins), or sleeping against ocean currents. There is.

New paper “Just keep swimming? Observation of resting behavior of gray reef sharks Medicaginus Ambryrrhinchus (Bleeker, 1856),” published this month. Fish Biology Journal This overturns our knowledge of one mandatory ram ventilator. The gray shark is an endangered reef-dwelling shark of the family Ceridae, and was a typical representative of sharks that move for breathing.

First evidence of a gray reef shark resting under a reef shelf in the Seychelles. Credit: Photography by Craig Foster | © Save Our Seeds Foundation

“During a routine research dive around Daros, we discovered a gray shark resting under a reef shelf,” said the head of research at the Save Our Seas Daros Research Center (SOSF-DRC) in the Seychelles. Dr. Robert Block begins speaking. “This is not something we believed they were capable of. Gray sharks have been thought of as a ram-breathing species that cannot rest, so when we find these sharks resting, It turns our basic understanding of them upside down.”

Stationary sharks: a surprising discovery

Researchers encountered gray sharks resting alone or in groups at various locations around the Seychelles. And all the while, the sharks seemed oblivious to the observer’s presence. This is an important observation. Scientists believe that increased arousal threshold is a characteristic of sleep, not just rest.

The sharks remained stationary except for mandibular movements, suggesting that these ram-ventilating sharks switch to buccal pumping behavior. Since there is little current at the site and the shark rests facing on all sides, the idea that resting facing the current is the only way to do so is because there is little water for gray reef sharks.

Craig Foster, founder of the SeaChange project, is one of the divers and an author of the paper. “There’s something special about tiptoeing around 25 meters underwater, staring into the open eyes of a sleeping shark, and moving carefully so as not to wake the peaceful, beautiful shark.” he says.

Implications and future research

“I love anything that challenges our current thinking, and I’ve always thought the gray reef shark is a clear example of a species that needs to swim to breathe. Obviously with this discovery. Dr James Lea, CEO of the Save Our Seas Foundation, is enthusiastic about the implications of this paper. “This raises all sorts of other questions,” he says. “How are they coping? For how long? How often? We still have a lot to learn, and that’s very exciting to me.”

If gray reef sharks can switch up their breathing and rest, we may be able to learn more about similar sharks. “It’s important to understand how they use their environment and how it changes in response to changing environmental conditions,” explains Dr. Lee. “How important is this rest, or even the possibility of sleep, for sharks? And how will they be affected if they are unable to rest if conditions change, such as rising or falling oxygen levels due to climate change? Will I receive it?”

remind us of our connection to nature

The authors all agree that this discovery also tells us a lot about ourselves and our relationship with the natural world. “I hope these discoveries remind us how much we still don’t know and how interesting that is. Science can get quite a lot wrong. That’s a lot, and that’s okay,” Dr. Block recalled. Foster believes what we know about the wild is critical to conservation. “Knowing how our shark family sleeps brings us closer to their fascinating world, and awakens us from our own slumber to remind us that we cannot live without these amazing marine creatures.” ,” he said.

Reference: “Just keep swimming? Observation of resting behavior of gray reef sharks Medicaginus Ambryrrhinchus (Bleeker, 1856)” by Robert W. Block, Craig Foster, and James S.E. Lee, November 20, 2023, Fish Biology Journal.
DOI: 10.1111/jfb.15623

Source: scitechdaily.com