Oligocene prehistoric dolphin discovery


This 9 July 2020 video says about itself:

A giant 16-foot long dolphin has been discovered. It lived 25 million years ago. It feasted on … whales and it was the apex predator of the ocean

Researchers found a full skeleton of a cetacean called Ankylorhiza tiedemani. It shared many similar features with both baleen whales and modern toothed whales. This dolphin had tusk-like front teeth. It lived in present-day South Carolina. Fossil evidence includes skull anatomy and teeth, a flipper and its vertebral column. It revealed that this large dolphin was a ‘top predator’ in the community. It was very clearly preying upon large-bodied prey like a killer whale.

Ankylorhiza was a ruthless ‘ecological specialist’ when it came to hunting. At about 16 feet long, it was about twice the size of average-sized dolphins. Ankylorhiza has proportionally large teeth with thickened roots. It is an adaptation for higher bite force. The teeth have longitudinal ridges which cut through flesh more efficiently. It is also believed to be the first marine animal that used echolocation. It used sound to obtain information about surroundings and to find food.

From ScienceDaily:

15-foot-long skeleton of extinct dolphin suggests parallel evolution among whales

July 9, 2020

A report in the journal Current Biology on July 9 offers a detailed description of the first nearly complete skeleton of an extinct large dolphin, discovered in what is now South Carolina. The 15-foot-long dolphin (Ankylorhiza tiedemani comb. n.) lived during the Oligocene — about 25 million years ago — and was previously known only from a partial rostrum (snout) fossil.

The researchers say that multiple lines of evidence — from the skull anatomy and teeth, to the flipper and vertebral column — show that this large dolphin (a toothed whale in the group Odontoceti) was a top predator in the community in which it lived. They say that many features of the dolphin’s postcranial skeleton also imply that modern baleen whales and modern toothed whales must have evolved similar features independently, driven by parallel evolution in the very similar aquatic habitats in which they lived.

“The degree to which baleen whales and dolphins independently arrive at the same overall swimming adaptations, rather than these traits evolving once in the common ancestor of both groups, surprised us,” says Robert Boessenecker of the College of Charleston in Charleston, South Carolina. “Some examples include the narrowing of the tailstock, increase in the number of tail vertebrae, and shortening of the humerus (upper arm bone) in the flipper.

“This is not apparent in different lineages of seals and sea lions, for example, which evolved into different modes of swimming and have very different looking postcranial skeletons,” he adds. “It’s as if the addition of extra finger bones in the flipper and the locking of the elbow joint has forced both major groups of cetaceans down a similar evolutionary pathway in terms of locomotion.”

Though first discovered in the 1880s from a fragmentary skull during phosphate dredging of the Wando River, the first skeleton of Ankylorhiza was discovered in the 1970s by then Charleston Museum Natural History curator Albert Sanders. The nearly complete skeleton described in the new study was found in the 1990s. A commercial paleontologist by the name of Mark Havenstein found it during construction of a housing subdivision in South Carolina. It was subsequently donated to the Mace Brown Museum of Natural History, to allow for its study.

While there’s much more to learn from this fossil specimen, the current findings reveal that Ankylorhiza was an ecological specialist. The researchers say the species was “very clearly preying upon large-bodied prey like a killer whale.”

Another intriguing aspect, according to the researchers, is that Ankylorhiza is the first echolocating whale to become an apex predator. When Ankylorhiza became extinct by about 23 million years ago, they explain, killer sperm whales and the shark-toothed dolphin Squalodon evolved and reoccupied the niche within 5 million years. After the last killer sperm whales died out about 5 million years ago, the niche was left open until the ice ages, with the evolution of killer whales about 1 or 2 million years ago.

“Whales and dolphins have a complicated and long evolutionary history, and at a glance, you may not get that impression from modern species,” Boessenecker says. “The fossil record has really cracked open this long, winding evolutionary path, and fossils like Ankylorhiza help illuminate how this happened.”

Boessenecker notes that more fossils of Ankylorhiza are awaiting study, including a second species and fossils of Ankylorhiza juveniles that can offer insight into the dolphin’s growth. He says that there’s still much to learn from fossilized dolphins and baleen whales from South Carolina.

“There are many other unique and strange early dolphins and baleen whales from Oligocene aged rocks in Charleston, South Carolina,” Boessenecker says. “Because the Oligocene epoch is the time when filter-feeding and echolocation first evolved, and since marine mammal localities of that time are scarce worldwide, the fossils from Charleston offer the most complete window into the early evolution of these groups, offering unparalleled evolutionary insight.”

Dolphins learning from other dolphins


This 2019 video says about itself:

Learn more about the Indo-Pacific bottlenose dolphins (Tursiops aduncus) that inhabit the Swan Canning Riverpark in Perth, Western Australia.

From ScienceDaily:

Dolphins learn foraging skills from peers

June 25, 2020

Dolphins can learn new skills from their fellow dolphins. That’s the conclusion of a new study reported in the journal Current Biology on June 25. The findings are the first to show that dolphins are not only capable of learning new ways to catch prey, but they are also motivated to learn from peers, not just from their mothers, the researchers say.

“Our study shows that the foraging behavior ‘shelling’ — where dolphins trap fish inside empty seashells — spreads through social learning among close associates,” says Sonja Wild, who conducted this research for her doctorate at the University of Leeds. “This is surprising, as dolphins and other toothed whales tend to follow a ‘do-as-mother-does’ strategy for learning foraging behavior.”

Another aspect that makes the findings especially intriguing is that shelling represents only the second reported case of tool use in dolphins. The dolphins of Shark Bay, Western Australia, are also known to use marine sponges as foraging tools to help them catch prey, according to the researchers.

Wild and her colleagues made the discovery during boat-based surveys in Shark Bay between 2007 and 2018. In almost 5,300 encounters with dolphin groups over that time, they identified more than 1,000 different Indo-Pacific bottlenose dolphins (Tursiops aduncus). They also caught a select few in the act of shelling 42 times.

“During shelling, dolphins chase their prey — usually a fish — into empty shells of giant gastropods, insert their beak into the shell, bring it to the water surface and then shake it about to drain the water out of the shell, so that the fish falls into their open mouth,” Wild explains.

The researchers saw 19 different individual dolphins perform this shelling behavior. They note that there are surely more ‘shellers’ in the population than they saw, since the whole event may only take a few seconds and could easily be missed. The question then was: how had this new way of foraging spread from one dolphin to the next?

To find out, the researchers used social network analysis, taking into account the social network, genetic relationships, and environmental factors. Their analysis concluded that the shelling behavior spreads socially primarily within — rather than between — generations, providing the first evidence that dolphins are also capable of learning from their peers, not just their mothers.

“The fact that shelling is socially transmitted among associates, rather than between mother and offspring, highlights the similarities between cetaceans [the group including dolphins, whales, and porpoises] and great apes in the way cultural behaviors are passed on,” says Michael Krützen, University of Zurich, who initiated the study.

“Indeed, despite having divergent evolutionary histories and occupying different environments, there are striking similarities between cetaceans and great apes: both are long-lived, large-brained mammals with high capacities for innovation and cultural transmission of behaviors,” he adds.

Wild noted that not all shelling dolphins seem to engage in the behavior at the same frequency. “Some dolphins use shells quite regularly during foraging, while others have only ever been seen with a shell once,” she says. “So, while there may be other explanations, it’s possible that some dolphins have mastered the skill more than others.”

Wild says that the findings have important implications for understanding how dolphins may be able to adapt behaviorally to changing environments. “Learning from others allows for a rapid spread of novel behaviors across populations, and it has been suggested that species with the capacity for learning from others in this way may be better able to survive,” she says.

Australian dolphin sounds may help conservation


This April 2016 video says about itself:

Surf and Turf Dolphins | Dolphins of Shark Bay

Traveling at speeds of up to 20 miles per hour, the surfing dolphins of Western Australia drive mullet onto the beach to trap them.

From Edith Cowan University in Australia:

Tuning into dolphin chatter could boost conservation efforts

April 29, 2020

Tuning in to the signature ‘whistles’ of dolphins could prove a game-changer in being able to accurately track the movements of this much-loved protected species.

Researchers from Edith Cowan University (ECU) and Curtin University in Australia have moved an important step closer to using sound rather than sight to track individual dolphin activity.

Their study, which has potential implications for dolphin communities around the world, investigated whether there was a way to attribute unique whistles to individual bottlenose dolphins living in Western Australia’s Swan River.

It is the first time researchers have attempted acoustic tracking dolphins in the Swan River, which is a complicated marine ecosystem due to its high volume of activity and noise.

ECU researcher Associate Professor Chandra Salgado Kent said the project could have significant implications for dolphin conservation.

“Our ultimate aim is to track the movements of individual dolphins through underwater acoustic recorders,” Professor Salgado Kent said.

“Until now researchers around the world have relied on laborious and expensive visual surveys on boats to track individual dolphins.

“These surveys can only be conducted during the day and rely on photographing the unique nicks and notches in dorsal fins when they come to the surface.

“We aimed to design a new approach to monitor individual dolphin activity through matching unique sounds, known as signature whistles, to individual dolphins.”

A challenging process

From April to September 2013 the researchers systemically monitored an area within the eastern part of the Fremantle Inner Harbour where the Swan River narrows.

Acoustic recordings were made throughout all observation times with handheld hydrophones deployed over the side of the small craft jetty lowered to 1.5m depth.

More than 500 whistles were matched to dolphin photos over the period of the study.

Curtin University Professor Christine Erbe said the process presented some unique challenges.

“Dolphins are social creatures and very frequently seen in groups, which makes the process of matching the whistles to particular individuals very challenging,” she said.

“Based on the presence and absence of dolphins when whistles were recorded, most whistle types were narrowed down to a range of possible dolphins that could have produced it.

“Our next goal will be to narrow this down to individuals.”

Why whales, dolphins swim so well


This 2015 video says about itself:

DOLPHINS & WHALES

Ute Margreff lives on Ireland’s Atlantic coast, Florian Graner in the Puget Sound in the Northwest of the USA. Both Germans share a deep passion for the sea and its creatures. About 10 years ago Ute Margreff got to know the female solitary dolphin Mara – it was the start of an unusual friendship. Florian Graner found its private paradise close to Seattle. Right in front of his doorstep he dives into a world inhabited by sea lions, giant octopus and orca whales. Both Ute and Florian fight for the protection of marine habitats, each one in a different and very unique way.

From Lehigh University in the USA:

Secrets to swimming efficiency of whales, dolphins

March 19, 2020

Summary: Recent work has examined the fluid mechanics of cetacean propulsion by numerically simulating their oscillating tail fins. A team developed a model that, for the first time, could quantitatively predict how the motions of the fin should be tailored to its shape in order to maximize its efficiency. The research could influence the design of next-gen underwater robots.

Someday, underwater robots may so closely mimic creatures like fish that they’ll fool not only the real animals themselves but humans as well. That ability could yield information ranging from the health of fish stocks to the location of foreign watercraft.

Such robots would need to be fast, efficient, highly maneuverable, and acoustically stealthy. In other words, they would have to be very much like bottlenose dolphins or killer whales.

“We’re interested in developing the next generation of underwater vehicles so we’re trying to understand how dolphins and whales swim as efficiently as they do,” says Keith W. Moored, an assistant professor of mechanical engineering and mechanics in Lehigh University’s P.C. Rossin College of Engineering and Applied Science. “We’re studying how these animals are designed and what’s beneficial about that design in terms of their swimming performance, or the fluid mechanics of how they swim.”

Moored is the principal investigator on a paper recently published in the Journal of the Royal Society Interface that examined the fluid mechanics of cetacean propulsion by numerically simulating their oscillating tail fins. For the first time, Moore and his team were able to develop a model that could quantitatively predict how the motions of the fin should be tailored to its shape to maximize its efficiency. The research was part of a larger project supported by the Office of Naval Research under its Multidisciplinary University Research Initiative program. The project, which received more than $7 million in funding (with $1 million going to Lehigh) over more than five years, also included the University of Virginia, West Chester University, Princeton University, and Harvard University.

The tail fins of cetaceans (whales and dolphins) come in a wide variety of shapes. The way these animals move their fins, or their kinematics, also varies. Some cetaceans may flap their fins at a greater amplitude, or pitch them at a steeper angle. Moored and his team wanted to better understand this interplay between the two variables to determine if tail fin shape was tailored to a specific set of kinematics.

Using the shape and kinematic data for five cetacean species (with common names of bottlenose dolphin, spotted dolphin, killer whale, false killer whale, and beluga whale), they ran simulations on each of the species to determine its propulsive efficiency. Then they swapped the data around, for example, running a simulation on the fin shape of a killer whale attached to the kinematics of a dolphin.

“We ran 25 of these swapped simulations, and we were really surprised,” says Moored. “The pseudo orca fin shape was always the best, meaning it was the most efficient. It didn’t matter what kinematics we gave it. And the beluga whale kinematics were always the best, regardless of which shape it was attached to. We didn’t expect that, so we started digging into it more and developed this relatively simplistic model of how efficiency scales with different kinematic and shape variables.”

The model worked well to capture the data that Moored and his team had already generated, so they extended their data set to examine any resulting trends. They found that their model not only predicted efficiency beyond their data set but also revealed that specific shapes were tailored to specific kinematics.

One interesting revelation, says Moored, was the fundamental interplay between circulatory forces and added mass forces that contribute to an animal’s movement. Circulatory forces are those that generate lift, like with aircraft.

“A tail that’s flapping up and down generates forces just like an aircraft, but it also generates added mass forces that have to do with how fast the fluid is being accelerated,” says Moored. “In the past, people didn’t think those added mass forces were that relevant in cetacean swimming. It’s not acknowledged at all in the previous literature. But we found that the accelerations of the fin are integral to predicting the trends of efficiency, and that was fascinating to us. It ultimately gives us a predictive model that’s accurate. Without it, we’d basically be saying that fin shape doesn’t change the efficiency, and that’s not true.”

Having a model that can predict performance based on shape and kinematics provides a basic design equation of sorts for building an underwater robot that performs like a cetacean. To date, these equations haven’t existed. And the potential for these machines is huge. Fast, efficient, and highly maneuverable fish-shaped robots could help researchers test hypotheses about how the animals swim, and better understand the behavior of fish schools. They could be used to detect submarines and other submersibles. They could also be used to monitor the impact of climate change on fish stock populations.

Moored and his team have already moved on and expanded their scaling model to account for a larger range of variables they then validated with experimental data. Ultimately, they want to build a far more predictive model. One that captures the effects of these variables, and can then predict performance for a range of applications.

“This fish swimming problem is a really exciting problem because it’s so complicated,” he says. “It’s fascinating to take this chaos of variables and see order in it, to see the structure in it, and to understand what’s fundamentally happening.”

Fishing net lights save turtles and dolphins


This June 2019 video from the USA says about itsfelf:

Reducing Bycatch Helps Restore Sea Turtle Populations

Bycatch—when animals are accidentally caught while people are fishing for other species—is the biggest threat to sea turtles in the ocean. This project is helping reduce sea turtle bycatch and restoring their populations after the Deepwater Horizon [BP] disaster.

From the University of Exeter in England:

Lights on fishing nets save turtles and dolphins

December 5, 2019

Placing lights on fishing nets reduces the chances of sea turtles and dolphins being caught by accident, new research shows.

LED lights along the top of floating gillnets cut accidental “bycatch” of sea turtles by more than 70%, and that of small cetaceans (including dolphins and porpoises) by more than 66%.

The study, by the University of Exeter and Peruvian conservation organisation ProDelphinus, looked at small-scale vessels departing from three Peruvian ports between 2015 and 2018, and found the lights didn’t reduce the amount of fish caught from “target species” (ie what the fishers wanted to catch).

The findings support previous research which suggested LED lights reduce bycatch of seabirds in gillnets by about 85%. Gillnets, which can be either anchored or move with the ocean currents, are designed to entangle or snare fish by the gills, and are the largest component of small-scale fisheries in many countries.

“Gillnet fisheries often have high bycatch rates of threatened marine species such as sea turtles, whales, dolphins and seabirds,” said lead author Alessandra Bielli, who carried out analyses as part of her master’s research at the Centre for Ecology and Conservation at Exeter’s Penryn Campus in Cornwall.

“This could lead to declines in the populations of these non-target species — yet few solutions to reduce gillnet bycatch have been developed.

“Sensory cues — in this case LED lights — are one way we might alert such species to the presence of fishing gear in the water.”

The researchers placed lights every 10m along the float line of 864 gillnets, pairing each with an unlit net to compare the results.

“The dramatic reduction in bycatch of sea turtles and cetaceans in illuminated nets shows how this simple, relatively low-cost technique could help these species and allow fishers to fish more sustainably. Given the success we have had, we hope other fisheries with bycatch problems will also try illuminating their fishing nets,” said Exeter PhD graduate Dr Jeffrey Mangel, of Peruvian NGO ProDelphinus.

Most of the turtles caught in the study were green turtles (86%), though loggerhead and olive ridley turtles were also caught.

Among the small cetaceans captured, 47% were long-beaked common dolphins, 26% were dusky dolphins and 24% were Burmeister’s porpoises.

“This work has further shown the usefulness of lights on nets to save wildlife. We now need lights that are ever more robust and affordable,” said Professor Brendan Godley, of the University of Exeter.

Fluid dynamics may help drones capture a dolphin’s breath in midair: here.

Bottlenose dolphin mother adopts melon-headed whale calf


This 5 August 2019 video says about itself:

Dolphin Mom Adopts a Calf From a Different Species | Nat Geo Wild

A bottlenose dolphin mother off the coast of French Polynesia was spotted caring for a melon-headed whale.

How dolphins form friendships, new research


This March 2019 video is called How to Identify Indo-Pacific Bottlenose Dolphins.

From the University of Bristol in England:

Dolphins form friendships through shared interests just like us, study finds

June 12, 2019

When it comes to making friends, it appears dolphins are just like us and form close friendships with other dolphins that have a common interest. The findings, published in the Proceedings of the Royal Society B by an international team of researchers from the Universities of Bristol, Zurich and Western Australia, provide further insight into the social habits of these remarkable animals.

Shark Bay, a World Heritage area in Western Australia, is home to an iconic population of Indo-Pacific bottlenose dolphins, and the only place where dolphins have been observed using marine sponges as foraging tools. This learnt technique, passed down from generation to generation, helps certain dolphins, “spongers”, find food in deeper water channels. While the tool-using technique is well-studied in female dolphins, this study looked specifically at male dolphins.

Using behavioural, genetic and photographic data collected from 124 male dolphins during the winter months in Shark Bay over nine years [2007 to 2015], the team analysed a subset of 37 male dolphins, comprising 13 spongers and 24 non-spongers.

Male spongers spend more time associating with other male spongers than they do [with] non-spongers, these bonds being based on similar foraging techniques and not relatedness or other factors.

Dr Simon Allen, a co-author of the study and senior research associate at Bristol’s School of Biological Sciences, explains: “Foraging with a sponge is a time-consuming and largely solitary activity so it was long thought incompatible with the needs of male dolphins in Shark Bay — to invest time in forming close alliances with other males. This study suggests that, like their female counterparts and indeed like humans, male dolphins form social bonds based on shared interests.”

The study provides new insight into homophilous behaviour in the social network of tool-using dolphins.

Manuela Bizzozzero, lead author of the study at the University of Zurich, added: “Male dolphins in Shark Bay exhibit a fascinating social system of nested alliance formation. These strong bonds between males can last for decades and are critical to each male’s mating success. We were very excited to discover alliances of spongers, dolphins forming close friendships with others with similar traits.”

The study was funded by grants from the Swiss National Science Foundation, National Geographic Society, Australia’s Sea World Research and Rescue Foundation Inc (SWRRFI), W.V. Scott Foundation and the A.H. Schultz Stiftung.

Brazilian river dolphins communication, new study


This 7 February 2020 video is called Can Colombia’s pink river dolphins be saved from extinction? | ITV News.

Another video used to say about itself:

A new species of river dolphin has been discovered by scientists working in Brazil. This is the fifth known species of its kind, and there are an estimated one thousand of the dolphins living in the Araguaia river basin.

Researchers from the Federal University of Amazonas ran genetic testing on some of the dolphins to be certain that a new species had been found. The last time a new species of river dolphin was discovered was back in 1918.

Doctor Tomas Hrbek, lead author of the study, is quoted as saying: “It is very similar to the other ones. It was something that was very unexpected, it is an area where people see them all the time, they are a large mammal, the thing is nobody really looked.” The Araguaia dolphins are smaller and reportedly have fewer teeth than the Amazon river dolphins, also called boto or pink dolphins, which are believed to be the most intelligent of the river dolphins.

From the University of Vermont in the USA:

Mysterious river dolphin helps crack the code of marine mammal communication

April 19, 2019

The Araguaian river dolphin of Brazil is something of a mystery. It was thought to be quite solitary, with little social structure that would require communication. But Laura May Collado, a biologist at the University of Vermont, and her colleagues have discovered that the dolphins can actually make hundreds of different sounds to communicate, a finding that could help uncover how communication evolved in marine mammals.

“We found that they do interact socially and are making more sounds than previously thought,” she says. “Their vocal repertoire is very diverse.”

The findings of May Collado are her colleagues were published in the journal PeerJ on April 18.

The Araguaian dolphins, also called botos, are a difficult animal to study. They are hard to find in the first place, and while the waters of the Araguaia and Tocatins rivers are clear, it is challenging to identify individuals because the dolphins are skittish and hard to approach.

Luckily, Gabriel Melo-Santos, a biologist from the University of St Andrews in Scotland and leader of the project, found a fish market in the Brazilian town of Mocajuba where the botos regularly visit to be fed by people shopping there. The clear water and regular dolphin visits provided a unique opportunity to get a close look at how the animals behave and interact, and to identify and keep track of various individuals.

The team used underwater cameras and microphones to record sounds and interactions between the dolphins at the market, and took some genetic samples. They identified 237 different types of sounds the dolphins make, but even with 20 hours of recordings the researchers don’t believe they captured the animals’ entire acoustic repertoire. The most common sounds were short, two-part calls that baby dolphins made when they were approaching their mothers.

“It’s exciting; marine dolphins like the bottlenose use signature whistles for contact, and here we have a different sound used by river dolphins for the same purpose,” says May Collado. The river dolphins also made longer calls and whistles, but these were much rarer, and the reasons for them are not yet clear. But there is some indication that whistles serve the opposite purpose than in bottlenose dolphins, with the botos using them to maintain distance rather than for group cohesion.

The acoustic characteristics of the calls are also interesting; they fall somewhere between the low-frequency calls used by baleen whales to communicate over long distances, and the high-frequency ones used by marine dolphins for short distances. May Collado speculates that the river environment may have shaped those characteristics.

“There are a lot of obstacles like flooded forests and vegetation in their habitat, so this signal could have evolved to avoid echoes from vegetation and improve the communication range of mothers and their calves,” she says.

May Collado and her colleagues next want to study whether the same diversity of communication is seen in other populations of Araguaian river dolphins that are less accustomed to humans, and compare them to their relatives elsewhere in South America. The Araguaian dolphins are closely related to two other species, the Bolivian river dolphin and Amazon river dolphin; the Araguaian dolphins were only described as a separate species in 2014, and that classification is still under debate. But there seems to be a large amount of variation in the repertoire of sounds each species makes.

The Amazon dolphins in Ecuador, studied by May Collado in 2005, are generally very quiet. “We need more information on these other species and more populations,” she says. “Why is one population chattier than others and how do these differences shape their social structure?”

May Collado says the work could help researchers gain clearer understanding of how communication evolved in marine mammals. Similar calls have been reported in pilot whales and killer whales, for example, and the similarities and differences between different species could help tease out which signals evolved first, and why.

The river dolphins are evolutionary relics, represented by just a few species around the world, and they diverged from other cetaceans much earlier than other dolphins. So these calls may have arisen first in river dolphins, then later evolved in marine dolphins into whistles and calls but in a different social context. Or was there a change in the function of the calls, with this kind of sound being used for group identity in killer whales, and individual identity in river dolphins? The calls may also have other functions in addition to identity, perhaps indicating group identity, or providing information on emotional state.

“We can’t say what the evolutionary story is yet until we get to know what sounds are produced by other river dolphins in the Amazon area, and how that relates to what we found,” she says. “We now have all these new questions to explore.”