Much of what researchers know about pygmy sperm whales has come from animals that wash ashore. Strandings are especially common along the southeastern United States, where this species appears more frequently than almost any other large marine mammal.

Whale Strandings Reveal Hidden Health Problems

Examinations of stranded whales have uncovered several recurring medical problems, including stomach ulcers. These ulcers are sometimes associated with Helicobacter, a group of bacteria that can live in the stomach and intestines of many animals, including humans and whales.

After reviewing more than 20 years of stranding records and preserved tissue samples, researchers at Florida Atlantic University’s Harbor Branch Oceanographic Institute and collaborating institutions identified three Helicobacter genotypes that had never been documented before.

The study, published in the Journal of Wildlife Diseases, marks the first confirmed discovery of these bacterial genotypes in pygmy sperm whales. The researchers named them Kogia Helicobacter 1, 2 and 3. Beyond offering new insight into an elusive whale species, the findings raise broader questions about how bacterial infections may affect marine wildlife and ocean health.

“Helicobacter bacteria have long been associated with gastrointestinal disorders in humans and other animals, including chronic gastritis, ulcers, and even gastric cancer,” said Annie Page, D.V.M., Ph.D., senior author, an associate research professor and clinical veterinarian at FAU Harbor Branch. “To find novel strains of these bacteria in a deep-diving whale species is intriguing.”

Three Bacterial Genotypes New to Science

From 1999 through 2020, FAU Harbor Branch responded to 59 pygmy sperm whale strandings. Post-mortem examinations were completed on 80% of those animals.

In four cases, scientists found spiral-shaped, “spirilliform” bacteria within stomach tissue. The team later reexamined the preserved samples using histopathology, molecular testing and DNA sequencing. That analysis revealed several previously unknown Helicobacter genotypes.

“Two of the genotypes, Kogia Helicobacter 1 and 2, are genetically similar to known Helicobacter species previously found in other cetaceans — such as dolphins and porpoises — and in humans,” said Wendy Marks, corresponding author and a research coordinator of the marine wildlife veterinary medicine and research lab at FAU Harbor Branch. “But Kogia Helicobacter 3 belongs to a more divergent lineage, which emphasizes the possibility that there are far more undiscovered bacteria in the ocean than we realize.”

Researchers found both Kogia Helicobacter 1 and 3 in the forestomach tissue of one whale.

Infected Whales Showed Stomach Damage

Each of the four whales that tested positive also showed clear signs of gastrointestinal disease.

“All four whales that tested positive for Helicobacter had visible gastric pathology,” said Page. “We saw signs of gastritis, gastric ulcers, fibrosis and nematode infestations. In one case, there was also colitis, which suggests that the infection may not be limited to the stomach. While Helicobacter wasn’t listed as the cause of death in any of the whales, these lesions raise questions about its role in gastrointestinal disease.”

The researchers did not conclude that Helicobacter directly caused the whales’ deaths. However, the repeated presence of inflammation, ulcers, tissue scarring and other digestive problems suggests the bacteria could contribute to chronic illness.

Helicobacter was first reported in marine mammals in 2000. Since then, related bacteria have been detected in several cetacean species around the world. In some animals, infection has been connected with low energy, loss of appetite, regurgitation, stomach ulcers and inflammation. Many of these symptoms are similar to those seen in infected humans.

Possible Risks for Vulnerable Whale Populations

“Whales, like humans, appear to be susceptible to certain microbial infections that we’re only beginning to understand,” said Marks. “If chronic Helicobacter infections are causing health issues in these animals, it could have implications not only for individual whale health, but for entire populations — especially for species that are already vulnerable.”

Because pygmy sperm whales are so difficult to study at sea, researchers still do not know how widespread the newly identified bacteria may be or how much they affect the animals over time. Additional testing will be needed to determine whether these infections contribute to illness, strandings or population-level health problems.

The project brought together researchers from FAU Harbor Branch, the University of Florida’s College of Veterinary Medicine, Colorado State University and Marine Mammal Pathology Services.

Decades of Stranding Research Pay Off

“This research underscores the value of long-term marine mammal stranding response programs,” said Page. “Without the ability to study these stranded animals over decades, we never would have discovered these bacteria. Every whale tells a story, and sometimes that story leads us into entirely new scientific territory.”

Study co-authors are Jessy Castellanos-Gell, Ph.D.; Steven Tillis, Ph.D.; James F.X. Wellehan, D.V.M., Ph.D., DACZM; and April Childress, all with the College of Veterinary Medicine, University of Florida; Nicole Pegg, FAU Harbor Branch; David Rotstein, D.V.M., Marine Mammal Pathology Services; Sushan Han, D.V.M., Ph.D., Diagnostic Medicine Center, Colorado State University; and Steve Burton, director, stranding and population assessment, FAU Harbor Branch.

The research was supported by the Florida State Specialty License Plate Program through the “Protect Florida Whales” grant, which is administered by the Harbor Branch Oceanographic Institute Foundation.

About 66 million years ago, two South American sauropods could rise onto their hind legs and remain there for relatively long periods, especially when they were young. This ability may have helped them reach leaves high in trees, appear more intimidating to predators, attract mates, or reproduce.

The dinosaurs, Uberabatitan from Brazil and Neuquensaurus from Argentina, were modest in size compared with the largest sauropods. Even so, they were roughly comparable to modern elephants. Adult Uberabatitans may have grown as long as 26 meters, making them the largest dinosaurs known from Brazil.

New research suggests that their ability to stand upright declined as they grew. Younger animals were better able to support themselves on two legs, while adults probably experienced much greater strain because of their increasing weight.

The findings come from a study supported by FAPESP and published in the journal Palaeontology. The international research team included scientists from Brazil, Germany, and Argentina.

Testing Dinosaur Bones With Engineering Tools

To investigate how sauropods handled the forces involved in standing upright, the researchers turned to a computational method commonly used in engineering.

Their goal was to estimate how much stress gravity and body weight placed on the femur, or thigh bone, when each dinosaur shifted its weight onto its hind legs.

“Smaller sauropods like these had a bone and muscle structure that allowed them to stand more easily and for longer on their two hind legs. Larger ones were probably also able to stand, but for a shorter time and with less comfort, since the position caused a lot of stress on the femur,” summarizes Julian Silva Júnior, a postdoctoral researcher at the School of Engineering of São Paulo State University (FEIS-UNESP) in Ilha Solteira, Brazil.

Silva Júnior is the study’s first author. He carried out the research during an internship at the University of Tübingen in Germany with a scholarship from FAPESP.

The team created digital reconstructions of the femurs of seven sauropod species. The selected dinosaurs represented different evolutionary branches, body sizes, and anatomical features. Their models were built from fossils preserved in natural history museums around the world.

Simulating the Forces of Standing Upright

The scientists used finite element analysis (FEA), a method that breaks a structure into many small sections and calculates how each part responds to pressure, weight, heat, or other forces. Engineers often use the same approach to test whether bridges, buildings, and machines can withstand stress.

“Using this technique, we performed two simulations. One dealt with the extrinsic scenario, simulating the force coming from outside to inside. In this case, gravity and the animal’s own weight on the femur when the dinosaur was standing on its hind legs. In the other, we analyzed the intrinsic scenario, the force that the muscles would exert on the femur,” Silva Júnior explains.

By combining the two simulations, the researchers estimated the total stress experienced by the femur of each species.

The lowest stress levels appeared in the two South American sauropods. One was a juvenile Uberabatitan ribeiroi (named after the Brazilian municipality of Uberaba, where it was found, and coincidentally, Silva Júnior’s hometown). The other was Neuquensaurus australis (found near the Neuquén River in Argentina).

Both lived during the Late Cretaceous period, about 66 million years ago.

Stronger Bones Gave Smaller Sauropods an Edge

The researchers found that the two species had particularly robust femurs. Their thicker, sturdier bones were better able to spread out the forces created when the animals stood upright.

“They had more robust femurs and could dissipate stress better. The bigger ones had very large muscles and even giant femurs, but not enough to support their weight. That doesn’t mean they couldn’t stand up, but they probably chose the best time to do so, because it must have been an uncomfortable position,” says the paleontologist.

Larger sauropods may still have been capable of rising onto their hind legs. However, the simulations suggest that they could not hold the pose as comfortably or for as long.

Adult Uberabatitan individuals probably faced the same problem. Although the juvenile examined in the study was well suited to standing upright, fully grown animals would have carried far more weight. That additional mass likely placed them under levels of stress similar to those experienced by other giant sauropods.

Why Sauropods May Have Stood on Two Legs

Standing upright could have provided several important advantages.

Sauropods were plant eaters, so rising onto their hind legs may have allowed them to reach vegetation high in trees that was unavailable to shorter animals. The posture could also have played a role in reproduction by allowing males to mount females or perform visual displays to attract potential mates.

The pose may also have served as a defensive strategy. By lifting the front of the body into the air, a sauropod would have appeared even larger and more threatening to approaching predators.

When supported by both hind legs and the tail, the animal would have formed a tripodal stance, meaning that three points of contact helped stabilize its body.

Important Limits of the Study

The researchers note that their models did not include every structure that would have affected how the dinosaurs stood.

For example, the simulations did not account for cartilage, the flexible tissue that cushions joints and can help absorb and distribute stress. They also did not model the support provided by the tail while the dinosaur was in a tripodal position.

Because cartilage was not analyzed in any of the seven specimens, the researchers assumed that it played a similar role across the species. This means the method is most useful for comparing the dinosaurs with one another rather than producing an exact measurement for each individual animal.

“The tool we use is very efficient for comparisons, even if the answer isn’t exact for each one. By comparing representatives from different lineages, we can get a fairly accurate picture of how these animals behaved millions of years ago,” says the researcher.

The new review examines aquatic deoxygenation, which refers to declining levels of dissolved oxygen in the ocean (ocean deoxygenation), coastal waters, rivers, lakes and streams. The researchers assessed how this growing problem interacts with the nine major Earth system processes included in the Planetary Boundaries framework.

Introduced in 2009, the framework identifies environmental processes that are essential for maintaining a stable and resilient planet. It also tracks how human activity is pushing those systems beyond safe conditions.

The nine planetary boundaries are climate change, ocean acidification, biodiversity loss, atmospheric aerosol loading, stratospheric ozone depletion, freshwater change, land-use change, chemical pollution and biogeochemical flows (including the nitrogen cycle). The researchers argue that dissolved oxygen levels should also be formally included.

“The health and stability of our planet depends on the health and stability of aquatic ecosystems, which need oxygen to function normally,” said lead author Erica Ferrer, a Scripps Oceanography alumna and current postdoctoral scholar at UC Santa Barbara’s National Center for Ecological Analysis and Synthesis. “This study is designed to elevate the profile of aquatic deoxygenation as a global threat and show that it does not operate in isolation.”

Warming and Pollution Are Draining Oxygen

Human-caused warming, excessive nutrient pollution and changes in the movement and ventilation of deeper waters are the main forces driving aquatic deoxygenation.

As oxygen levels fall, they can disrupt the biological and chemical processes that help regulate Earth’s climate. The decline also threatens organisms across aquatic food webs, from microscopic life to fish and sharks.

Marine mammals can also suffer even though they breathe air at the surface. Oxygen loss can reduce or relocate their prey, damage habitats and alter the food webs they depend on.

Connecting Deoxygenation to Other Planetary Risks

Ferrer and Scripps biological oceanographer Lisa Levin, the study’s senior author, developed the idea for the review after attending COP25, the 2019 United Nations Climate Change Conference held in Madrid.

They hope the findings will encourage researchers and policymakers to examine aquatic oxygen loss alongside climate change, pollution, biodiversity decline and other pressures on the planet rather than treating it as a separate problem.

“Adding aquatic deoxygenation to the Planetary Boundaries framework will help us understand its impacts on Earth system stability,” said Ferrer. “Mitigating its impacts represents a critical component of maintaining biodiversity and climate.”

Research Support and Publication

Ferrer completed the review during her doctoral research at Scripps. Her work was supported by the National Science Foundation’s Graduate Research Fellowship Program, graduate funding from Scripps and UC San Diego, and later postdoctoral support from UC Santa Cruz and UC Santa Barbara.

The study was published June 30, 2026, in the journal Limnology and Oceanography.

Additional authors include four former Scripps PhD students: Shailja Gangrade, Lillian McCormick, Ariel Pezner and Yassir Eddebbar, who is now a Scripps climate scientist. Other contributors were De’Marcus Robinson of UCLA, Véronique Carcon of the Institut de Physique du Globe de Paris and Kevin Rose of the Rensselaer Polytechnic Institute.