Killer Whales Surround Great White Sharks and Feast on Their Livers

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

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

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

Transplanting Pig Livers into Living Humans Achieves Near-Normal Functionality

Surgeons carry out a pig liver transplant at the First Affiliated Hospital of Anhui Medical University in China in May 2024.

Lu Xianfu

Transplants of organs from non-human animals to human recipients could transform medicine and potentially save countless lives each year as many die awaiting transplants. Past experiments have seen pig hearts and kidneys transplanted into humans, but this marks the first instance of an animal liver being transplanted into a living person.

“This is truly groundbreaking,” remarks Heiner Wedemeyer from Hannover Medical School in Germany, who was not involved in the procedure. “The patient was critically ill, but thanks to the transplant, he survived for six months.”

The complexities of the liver have prevented previous surgeries of this kind. Earlier studies were conducted on brain-dead individuals, but indications of success were observed. “The heart acts merely as a muscle for pumping blood,” Wedemeyer explains. “Kidneys are simpler as they filter waste. The liver, however, is unique as it synthesizes a variety of proteins essential for numerous metabolic functions.”

Similar early successes were noted in heart and kidney transplants, although subsequent complications arose. In the realm of heart transplantation, risks potentially include the spread of swine viruses.

Recently, Hokujo Taiyo and colleagues at Anhui Medical University reported a pig liver transplant performed on a 71-year-old man. His liver was deemed too damaged for a traditional transplant due to severe tumor growth and significant scarring from hepatitis B. Thousands perish annually awaiting liver transplants, so each surgical case must be meticulously justified, according to Sun.

However, Sun indicated that the man required some form of transplant as there was a risk of the tumor rupturing, which could be life-threatening. With the patient’s consent, Sun and his team replaced the affected portion of the liver with one harvested from an 11-month-old minipig in May 2024. During a five-hour procedure, they connected the blood vessels of the pig liver to those of the left side of the recipient’s own liver.

To mitigate the risk of rejection by the immune system, three pig genes were disabled while seven human genes were introduced, enhancing compatibility. The patient was also administered immunosuppressants while the team diligently examined his liver to ensure it was free from swine viruses.

Almost immediately post-surgery, the new liver began to produce bile. Bile is crucial for the digestion of fats. Within weeks, levels of bile and albumin (a protein that retains fluid within blood vessels) in the patient rose to healthy ranges, as reported by Sun.

Nevertheless, about a month post-transplant, a life-threatening blood clot formed in a blood vessel, necessitating the removal of the graft. This complication likely stemmed from an overactive immune response, leading to abnormal blood-clotting protein levels—a challenge that may be common in pig transplants given the biological differences between species.

The patient lived for roughly five additional months with only the left side of his liver remaining before succumbing to gastrointestinal bleeding, a frequent issue associated with liver scarring, according to Sun. Both Sun and Wedemeyer believe this bleeding was probably not related to the transplant.

Despite the outcome, the operation is seen as a partial success because the patient would likely have died very soon after the tumor’s removal, noted Wedemeyer. Furthermore, he added that the patient’s liver may have partially regenerated during the successful functioning of the transplant, enabling survival for several months after the graft removal.

Wedemeyer emphasized that this procedure enhanced the understanding of xenotransplantation and opened up the possibility of pig livers providing temporary solutions for patients awaiting human transplants. There may even be a chance that the remaining liver tissue could grow sufficiently to negate the need for further treatment, indicated Sun.

However, Sun cautioned that it may take at least ten years before pig livers can replace human livers permanently. He stressed the need to minimize potential complications through further genetic advancements.

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Source: www.newscientist.com

Tiny robots may soon navigate human livers to combat cancer

Science fiction has often depicted microscopic robots, but these tiny machines have become a reality with a wide range of real-world applications such as disease prevention and building repair.

A Canadian research team is now focusing on using these small robots to target liver cancer in various fields. They are working on using them in conjunction with MRI equipment to treat diseases (source).

A series of small biocompatible robots, made of magnetizable iron oxide nanoparticles guided by an external magnetic field, could potentially deliver medical care in a highly targeted manner.

Despite the potential of this technology, it faces a major technical challenge. The gravity of these microrobots exceeds the magnetic force, limiting their guidance if the tumor is located higher than the injection site.

To address this challenge, Dr. Jill Soules, a researcher at the CHUM Research Center at the University of Montreal, developed an algorithm that combines gravity and magnetic navigation forces to guide the microrobots into the arterial branches that feed the tumor.


This research has the potential to change the way liver cancer is treated with radiation therapy, which is the most common type of cancer causing 700,000 deaths annually worldwide.

Dr. Soulez emphasized the advantages of the magnetic resonance navigation technique, indicating that the tumor is better visualized on MRI than on X-ray.

In an experiment using pigs to recreate anatomical conditions, the researchers successfully navigated the hepatic artery branches of the animals and arrived at their destination using the microrobots.

Furthermore, using an anatomical atlas of the human liver, the researchers were able to simulate microrobot maneuvers on 19 patients treated with transarterial chemoembolization, finding that in more than 95% of cases, the location of the tumors matched the navigation algorithm to reach the targeted tumor.

Despite these significant advances, clinical application of this technology is still in the distant future, as artificial intelligence models need further training and improvements for real-time navigation of microrobots to the liver.

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Source: www.sciencefocus.com