Tag Archives: Preying

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

New research uncovers Asian Hornets preying on nearly 1,500 invertebrate species

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Biologist of University of Exeter We conducted the first large-scale study on Asian Hornet diets (Vespa Velutina), exploiting deep sequences to characterize the intestinal content of larvae in Jersey, France, Spain and the UK. European honeybees were the most common species found in the Hornets, but their diet is much broader. The analysis detected 1,449 invertebrate species, increasing the prey abundance of samples from south latitude.

Asian Hornet (Vespa Velutina). Image credit: Gilles San Martin/CC BY-SA 2.0.

The invasive species of Asian hornets are now found in much of Western Europe.

The nests are destroyed every year in mainland Britain as authorities try to lock out the seeds.

“The University of Exeter has been working hard to understand,” said Dr. Sifreya Pedersen, a researcher at the University of Exeter.

“Diets vary strongly across seasons and regions, indicating that they are highly flexible predators.”

“Most insect populations are reduced due to factors such as habitat destruction and chemical contamination.”

“The expanded areas where the Hornets live in Asia pose an extra threat.”

In this study, Dr. Pedersen and colleagues used a method called deep sequencing to identify the visceral prey species of over 1,500 Asian hornet larvae eating foods offered by adult hornets.

Of the top 50 invertebrate prey species identified, 43 are known to visit flowers. Among these were pollinators of three major European crops.

“Insects play an important role in enabling ecosystems to function, including pollination, decomposition and pest control,” Dr. Pedersen said.

“Our research provides important additional evidence of the threat posed as the Asian Hornets spread across Europe,” said Dr. Peter Kennedy of the University of Exeter.

The researchers identified 1,449 operational taxonomic units in the internal organs of hornet larvae.

More than half could be identified as a specific species, but the rest could not. Therefore, the exact number of species contained in the sample is not certain.

“We have provided the most comprehensive view of the European Asian Hornet diet to date, highlighting the highly broad and flexible potential prey,” the scientist said.

“The dietary composition shows that it differs across geographical regions and throughout the Hornets' active season, indicating high adaptability to new ecosystems. It drives both the invasive success of Asian hornets and the risks they pose to a wide range of native invertebrate fauna.”

“The growing prevalence of dietary bees in Europe has agreed to previous research and reports from beekeepers, supporting concerns about the risks of aquaculture.”

“Our results found that Asian hornets exhibit high predation frequencies on wild pollinators and recyclers, revealing further potential ecosystem-level pressures, implying a threat to the diversity of pollinators and recyclers and the resulting ecosystem services.”

study Published in the journal The science of the total environment.

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Siffreya Pedersen et al. The broad ecological threat of invasive hornets has been revealed through a deep sequencing approach. The science of the total environmentPublished online on March 4th, 2025. doi:10.1016/j.scitotenv.2025.178978

Source: www.sci.news

Why do killer whales target and attack porpoises instead of preying on them?

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Killer whales have been observed harassing porpoises in the Salish Sea, a behavior that has puzzled scientists for years. A study by Wild Orca and the SeaDoc Society at the University of California, Davis is investigating what may be behind it.Credit: Wild Orca

Scientists are investigating mysterious behavior.

Scientists have long been perplexed by the behavior of fish-eating killer whales in the Pacific Northwest. Killer whales have been seen harassing porpoises and sometimes killing them instead of eating them.

In a recently published study, marine mammal scienceCo-led by Deborah Giles of Wild Killer Whales and Sarah Teman of the Sea Dog Society, a program at the University of California, Davis School of Veterinary Medicine, the 60-year record between southern killer whales and porpoises in the Salish Sea We investigated the above interactions. You can better understand why they exhibit this behavior.

Southern killer whales are endangered, with only 75 individuals left. Their survival is closely tied to the fate of Chinook salmon, which is also an endangered species. seed. Without enough Chinook salmon, these whales are at risk of extinction.

“I’m often asked: Why don’t southerners eat seals and porpoises instead?” Giles said. “That’s because fish-eating killer whales have a completely different ecology and culture than marine mammal-eating killer whales, even though they live in the same ocean area. Therefore, interactions with porpoises We must conclude that there is another purpose, but this purpose has hitherto been speculative.”

Three plausible explanations

Scientists recorded instances of southern resident killer whales harassing porpoises as early as 1962, but the reason for this behavior remained a mystery for a long time. Giles, Teman, and a team of collaborators analyzed his 78 porpoise harassment incidents recorded from 1962 to 2020. This study suggests three plausible explanations.

  • Social play: Harassing porpoises may be a form of social play for killer whales. Like many intelligent species, these whales may engage in playful activities to bond, communicate, or simply have fun. This behavior can benefit group coordination and teamwork.
  • Hunting practice: Another hypothesis suggests that harassing porpoises may hone their salmon-hunting skills. Southern resident killer whales may view porpoises as moving targets to practice their hunting skills, even if they don’t intend to eat them.
  • Abusive behavior: This theory suggests that the whales may be trying to care for porpoises that they perceive to be weak or sick. This is an expression of the whale’s natural tendency to help other dolphins in the group. Females have been seen carrying dead calves, as well as porpoises.

“Abusive behavior, also known to scientists as ‘left-behind behavior,’ may be due to children having limited opportunities to care for them,” Giles explained. “Our research found that malnutrition causes nearly 70 percent of southern killer whale pregnancies to miscarry or for the calves to die shortly after birth.”

salmon specialist

Despite these interesting insights, Giles, Teman, and their collaborators acknowledge that the exact reasons behind porpoise harassment may never be fully understood. .But what is clear is that porpoises do not have Part of the diet of southern resident killer whales. Southern killer whales have a diet so specialized in salmon that the idea of ​​them eating porpoises is highly unlikely.

“Orcas are incredibly complex and intelligent animals. We found that harassing behavior toward porpoises has been passed down through generations and across social groups. It’s a great example,” says Teman. “Still, we don’t expect southern-dwelling killer whales to start eating porpoises. The salmon-eating culture is deeply rooted in southern-dwelling societies. For these whales to survive, healthy salmon populations are essential. We need numbers.”

This study highlights the importance of protecting salmon populations in the Salish Sea and throughout whale range. Maintaining an adequate supply of salmon is critical to the survival and well-being of Southern killer whales and the overall health of the Salish Sea ecosystem.

affinity for play

The study was conducted at a time when distinct killer whale populations on the Iberian Peninsula drew international headlines for interacting, sinking ships three times off the coasts of Portugal and Spain. After all, southern killer whales and killer whales of the Iberian Peninsula are two distinct populations with different cultures. What the two have in common is an affinity for play behavior.

Reference: “Harassment and Killing of Porpoises by Fish-Eating Southern Resident Killer Whales (Orcinus orca) (‘Phocoenacide’)” Deborah A. Giles, Sarah J. Teman, Samuel Ellis, John K.B. Ford, Monica W. Shields, M. Bradley Hanson, Candice K. Emmons, Paul E. Cottrell, Robin W. Baird, Richard W. Osborn, Michael Weiss, David K. Ellifritt. , Jennifer K. Olson, Jared R. Towers, Graham Ellis, Dena Matkin, Courtney E. Smith, Stephen A. Laverty, Stephanie A. Norman, Joseph K. Gaydos, September 28, 2023 , marine mammal science.

DOI: 10.1111/mms.13073

This research was funded by Wild Orca and the SeaDoc Society. Additional partners include the University of Exeter, Fisheries and Oceans Canada, Orca Behavior Institute, National Oceanic and Atmospheric Administration, Cascadia Research Institute, Whale Museum, Center for Whale Research, Ocean Research College Academy (ORCA) at Everett Community College, and Gulf Zoology. , North Gulf Coast Marine Society, George Mason University, Institute of Marine Medicine.

Source: scitechdaily.com