Baleen whale evolution, new research


This 10 May 2018 video says about itself:

This Huge, Ancient Whale Would Have Ripped You to Shreds

The weird marine beast, called Llanocetus denticrenatus, lived about 34 million years ago. It was big. It was an early ancestor of modern humpbacks and blue whales. And (this is the maverick, rule-breaking bit for a whale of its type) it had thick gums studded with teeth.

Today, all the biggest whales are filter feeders, while only [relatively] small whales of the Odontocetl group (including belugas, sperm whales, and all dolphins and porpoises) still chew their food. Modern large whales instead suck huge volumes of water through stringy bristles in their mouth called baleen, separating out tons of tiny organisms, which they digest en masse. This is such an essential feature of the group of massive whales, or Mysticetes, to which L. denticrenatus also belongs, that biologists call whales in this group baleen whales.

From ScienceDaily:

Ancient skull shows early ‘baleen whale’ had teeth

May 10, 2018

Today’s baleen whales (Mysticetes) support their massive bodies by filtering huge volumes of small prey from seawater using comb-like baleen in their mouths much like a sieve. But new evidence reported in the journal Current Biology on May 10 based on careful analysis of a 34-million-year-old whale skull from Antarctica — the second-oldest “baleen” whale ever found — suggests that early whales actually didn’t have baleen at all. Their mouths were equipped instead with well-developed gums and teeth, which they apparently used to bite large prey.

“Llanocetus denticrenatus is an ancient relative of our modern gentle giants, like humpback and blue whales,” says Felix Marx of the Royal Belgian Institute of Natural Sciences. “Unlike them, however, it had teeth, and probably was a formidable predator.”

“Until recently, it was thought that filter feeding first emerged when whales still had teeth”, adds R. Ewan Fordyce at the University of Otago in New Zealand. “Llanocetus shows that this was not the case.”

Like modern whales, Llanocetus had distinctive grooves on the roof of its mouth, the researchers explain, which usually contain blood vessels that supply the baleen. In Llanocetus, however, those grooves cluster around tooth sockets, where baleen would have been useless and at risk of being crushed.

“Instead of a filter, it seems that Llanocetus simply had large gums and, judging from the way its teeth are worn, mainly fed by biting large prey,” Marx says. “Even so, it was huge: at a total body length of around 8 meters, it rivals some living whales in size.”

The findings suggest that large gums in whales like Llanocetus gradually became more complex over evolutionary time and, ultimately, gave rise to baleen. That transition probably happened only after the teeth had already been lost and whales had switched from biting to sucking in small prey — as many whales and dolphins now do. Marx and Fordyce suggest that baleen most likely arose as a way to keep such small prey inside the mouth more effectively.

Soft tissues, including baleen, normally rot away, making it difficult to study their evolution. As a result, researchers must rely on indicators preserved on the bones, such as tell-tale grooves or lumps indicating the position of a muscle, or holes for the passage of particular blood vessels and nerves.

“Llanocetus presents a lucky combination, where the shape of the bones, small features suggesting the course of soft tissues, and tooth wear all combine to tell a clear story,” Fordyce says. “Crucially, Llanocetus is also extremely old and lived at the very time when Mysticetes first appeared. As such, it provides a rare window into the earliest phase of their evolution.”

In the new study, Fordyce and Marx found that the broad rostrum of Llanocetus had sharp, widely spaced teeth with marked tooth wear suggesting that they were used to bite and shear prey. As in living Mysticetes, the palate bears many grooves, which have commonly been interpreted as evidence for baleen. However, the researchers showed that those grooves instead converged on the bony tooth sockets, suggesting a peri-dental blood supply to well-developed gums, rather than racks of baleen.

The findings show that the evolution of filter feeding wasn’t as straightforward as previously thought, the researchers say. They’d now like to sort out when filter feeding and baleen first evolved.

“The giants of our modern ocean may be gentle, but their ancestors were anything but,” Marx says. “Llanocetus was both large and a ferocious predator and probably had little in common with how modern whales behave.”

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Fossil baleen whale discovery in New Zealand


This video says about itself:

36.4M-Year-Old Fossilized Skeleton May Be Oldest Baleen Whale Relative

12 May 2017

Whale fossil found in Peru is the oldest-known baleen whale relative ever discovered, according to research published May 11 in Current Biology.

From the University of Otago in New Zealand:

New genus and species of extinct baleen whale identified

April 18, 2018

University of Otago palaeontologists are rewriting the history of New Zealand’s ancient whales by describing a previously unknown genus of baleen whale, alive more than 27.5 million years ago and found in the Hakataramea Valley.

The new genus and species of extinct baleen whale is based on a skull and associated bones unearthed from the Kokoamu Greensand, a noted fossil-bearing rock unit in the South Canterbury and Waitaki district from the Oligocene period, which extends from about 33.9 million to 23 million years ago. At this time, New Zealand was an archipelago surrounded by shallow, richly productive seas.

Former PhD student in the University of Otago’s Department of Geology, Cheng-Hsiu Tsai and his supervisor, Professor Ewan Fordyce, have named the new genus Toipahautea waitaki, which translates in Māori as a baleen-origin whale from the Waitaki region.

Professor Fordyce says the discovery is significant in New Zealand’s fossil history.

“This is a pretty old whale that goes almost half-way back to the age of the dinosaurs. We are tracking whale history back through time”, Professor Fordyce explains.

“This newly-named whale lived about 27.5 million years ago. It’s about as old a common ancestor as we have for the living baleen whales like the minke whales and the right whales.”

Baleen whales are a group of Mysticeti, large whales usually from colder waters that lack teeth but have baleen plates in the upper jaw which are used to filter food such as krill out of large quantities of seawater.

The fossil was actually recovered from the Hakataramea Valley in South Canterbury 30 years ago in January 1988. However, it was only worked up in recent years with Dr Tsai — who is now currently working at the National Taiwan University — beginning his thesis only a few years ago. The thesis provided the analytical framework to identify and name the new whale.

The research paper announcing the new archaic baleen whale was published today in the scientific journal Royal Society Open Science.

While the skeleton of the whale was disarticulated when it was excavated, the bones were closely associated, which gave the palaeontologists plenty of material to work with. In particular, the highly diagnostic earbones were preserved, helping with identification.

The skull was about one metre long and the body about five metres, which means it was a reasonably small species, Professor Fordyce says. “That’s about half the size of an adult minke whale.”

It was previously known that the baleen whales can take on board thousands of litres of water in the lower jaws which they scoop open to get great mouthfuls of water and food. Toipahautea waitaki’s jaws were toothless, long and narrow, Professor Fordyce says, suggesting that it fed in a similar way to the modern-day minke whales.

The researchers were not able to determine how this whale died. Professor Fordyce says it could have been attacked by a shark, stranded on a beach or died of disease. When it died, it sank to the bottom of the sea floor with its skeleton falling apart and becoming a hub for coral and other organisms to grow on.

Professor Fordyce expects the ancient whales’ history books may keep being rewritten in years to come.

“We are pretty sure there are some species [of baleen whale] that will be older than these. But right now it anchors the modern baleen whale lineage to at least 27.5 million years.”

The Toipahautea waitaki fossil was collected during fieldwork funded by a grant from the National Geographic Society with further lab work also funded by the Society.

Why are whales so big?


This 2016 video is called National Geographic – Blue Whale, biggest animal on earth. Wild Sri Lanka.

From Stanford’s School of Earth, Energy & Environmental Sciences in the USA:

Why are whales so big?

Why aquatic mammals need to be big, but not too big

March 26, 2018

Summary: Examining body sizes of ancient and modern aquatic mammals and their terrestrial counterparts reveals that life in water restricts mammals to a narrow range of body sizes — big enough to stay warm, but not so big they can’t find enough food

Anyone who has witnessed majestic whales or lumbering elephant seals in person would be forgiven for associating ocean life with unlimited size in mammals, but new research reveals that mammal growth is actually more constrained in water than on land.

This finding by Stanford researchers is in contrast to previous theories suggesting that pressure on body size should be more relaxed in water, perhaps because of the large environment and ability for animals to float rather than have to support their body weight on legs.

Instead, the group found that aquatic mammal size is bounded at the small end by the need to retain heat and at the large end by difficulties getting enough food to survive. The group published their findings March 26 in Proceedings of the National Academy of Sciences.

“Many people have viewed going into the water as more freeing for mammals, but what we’re seeing is that it’s actually more constraining”, said co-author Jonathan Payne, a professor of geological sciences at Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “It’s not that water allows you to be a big mammal, it’s that you have to be a big mammal in water — you don’t have any other options.”

Getting big, but not too big

Although mammals that live in water share a similarly oblong body shape, they are not closely related. Rather, seals and sea lions are closely related to dogs, manatees share ancestry with elephants, and whales and dolphins are related to hippos and other hoofed mammals.

To learn more about how these groups of land mammals took on their characteristic girth when they turned aquatic, the researchers compiled body masses for 3,859 living and 2,999 fossil mammal species from existing data sets. The analysis includes about 70 percent of living species and 25 percent of extinct species. They analyzed the data with a set of models developed in collaboration with Craig McClain of the Louisiana Universities Marine Consortium.

From this analysis, the group found that once land animals take to the water, they evolve very quickly toward their new size, converging at around 1,000 pounds. Smaller ancestors like dog relatives increased in size more than larger ancestors like hippos to reach that optimal weight, suggesting that bigger is better for aquatic life, but only up to a point. The group points out that otters, which took to the water more recently, don’t follow that trend, perhaps because many otter species still live much of their lives on land.

“The key is having a phylogenetic tree to understand how these species are related to one another and the amount of time that has taken place between different evolutionary branching events,” said lead author Will Gearty, a graduate student at Stanford Earth. “The tree of ancestral relationships allows us to build models based on data from modern species to predict what the ancestors’ body sizes would have been and see what evolutionary trajectories best fit with what we see in the modern day.”

Heat and food

The group argues that the larger size helps aquatic mammals retain heat in water that’s lower than body temperature. “When you’re very small, you lose heat back into the water so fast, there’s no way to eat enough food to keep up”, Payne said.

They also suggest that metabolism increases with size more than an animal’s ability to gather food, putting a boundary on how big aquatic mammals can grow. “Basically, animals are machines that require energy to operate. This need for energy places hard limits on what animals can do and how big they can be,” said McClain, who was a co-author on the study.

“The range of viable sizes for mammals in the ocean is actually smaller than the range of viable sizes on land,” Payne said. “To demonstrate that statistically and provide a theory behind it is something new.”

If otters are the exception at the small end, baleen whales prove the exception at the larger size. These whales expend much less energy on feeding than their toothed counterparts because they filter all their food, which makes them more efficient and allows them to grow larger than toothed whales.

“The sperm whale seems to be the largest you can get without a new adaptation”, Gearty said. “The only way to get as big as a baleen whale is to completely change how you’re eating.”

The researchers began working on the study in 2014 and they are currently assessing how well similar approaches can be used to explain body size distributions in other animal groups, especially those that have both terrestrial and aquatic species.

“The hope is there’s simpler explanations that can apply to other species, including terrestrial animals,” Payne said. “It opens up some possibility that body size can be explained by basic principles of physics and chemistry.”

Payne is also a member of Stanford Bio-X and an affiliate of the Stanford Woods Institute for the Environment.

North Atlantic right whales’ voices, new research


This video from the USA says about itself:

22 January 2016

The North Atlantic right whale is an endangered species with as few as 500 that exist in the waters from Canada to Florida. This educational video is designed to increase the public knowledge on right whales. FAU Harbor Branch, College of Education’s Pine Jog and College of Science; and Marine Resources Council with assistance from Florida Fish and Wildlife Commission and National Marine Fisheries Service, produced this video utilizing Protect Florida Whale specialty license plate funds.

From Syracuse University in the USA:

Voice control: Why North Atlantic right whales change calls as they age

February 27, 2018

Former Syracuse postdoctoral researcher Holly Root-Gutteridge has always been a good listener — a trait that has served her very well in her bioacoustic research of mammals, both aquatic and landlocked. Most recently her ears have tuned-in to vocal stylings of the North Atlantic right whale.

Through extensive listening and analysis of whale calls — which were recorded by a large collaboration of scientists over the past two decades — Root-Gutteridge was able to pick up the slow gradual changes in sound production in the marine giants as they age. Looking at spectrograms of the calls, which provide visual representations of the sound, the research team could see the progression of vocal characteristics of the animals from calf throughout adulthood.

The whales produced clearer, longer calls with age, a trend that did not end when they reached physical maturity, as had been predicted.

“We’re learning that these right whales can have more control of their voices,” explains the bioacoustics researcher. “That means they may be sending more complex information than we previously thought.”

Through continued study, Root-Gutteridge believes that scientists will be able to better understand how whales communicate in the wild, which can lead to stronger worldwide conservation efforts of the sea mammals.

Root-Gutteridge’s newest investigation “A lifetime of changing calls: North Atlantic right whales, Eubalaena glacialis, refine call production as they age”, a collaborative research project with researchers from Syracuse University, Cornell University, Duke University and the National Oceanic and Atmospheric Administration (NOAA) Northeast fisheries office, was recently published in the March edition of the journal Animal Behaviour. The paper is based on work that was done while she was a researcher in the lab of Associate Professor, Susan Parks.

While still at Syracuse, Root-Gutteridge turned heads around the world with her wolf dialect research back in 2016. Contrasting the recordings of over 2,000 howls from 13 different species and subspecies of wolves, the biologist discovered that wolves, much like people, have regional vocalization patterns, or dialects, depending on their locale.

“I learned a lot at Syracuse as I’d never studied marine mammals before. I know a lot more about whales and their songs and have developed some great skills in analyzing animal sound”, says Root-Gutteridge. “I also have a much better understanding of how tough it is to study marine mammals as their home ranges are just so big. When I studied wolves, I thought 25 square miles was a lot of territory to cover, but the whales swim all the way up and down the East Coast!”

Since finishing at Syracuse, her work has literally gone to the dogs. Root-Gutteridge is currently at the University of Sussex in the United Kingdom where her next bioacoustics project, “How Dogs Hear Us: Human speech perception by domestic dogs”, explores what animals of the canine persuasion hear when humans speak.

New validation study analyzing hormone profile shows the duration and negative effects of fishing gear entanglement on the North Atlantic right whale — one of the most endangered whale species. Providing information on foraging success, migration behavior and body functioning, this technique can be used to study other baleen species to understand the impact of fishing activity on threatened whale populations: here.

Antarctic minke whale’s camera video


This video says about itself:

Explore the Antarctic From the Back of a Minke Whale | National Geographic

21 February 2018

Little is known about Antarctica’s elusive minke whales, but for the first time, scientists attached a camera to the back of one of the giant creatures to get a glimpse into their secretive underwater world.

Narwhals, new research


This video is called Narwhals | World’s Weirdest.

From the American Geophysical Union:

Mysterious lives of narwhals

February 9, 2018

Narwhals are some of the most elusive creatures in the ocean, spending most of their lives in deep water far from shore. But research being presented at the 2018 Ocean Sciences Meeting here on Monday may shed a bit of light on these enigmatic marine mammals.

New research shows narwhals may prefer to congregate near unique glacier fjords with thick ice fronts and low to moderate calving activity, where icebergs break off infrequently. It appears narwhals prefer the freshwater coming off still, serene glaciers over the silt-filled runoff discharged from very active glaciers.

The findings could help scientists understand a little more about the elusive narwhal and how these marine mammals might fare in a changing climate, according to the researchers.

“Arctic marine mammals are really good indicators of climate change because they are very specialized,” said Kristin Laidre, a scientist at the University of Washington in Seattle who will present the research Monday at the 2018 Ocean Sciences Meeting, co-sponsored by the Association for the Sciences of Limnology and Oceanography, The Oceanography Society and the American Geophysical Union. “They are finely attuned to specific environmental conditions, so they are good indicator species for how the physical changes many scientists are documenting in the Arctic can reverberate throughout the ecosystem.”

Scientists have known narwhals spend time at the fronts of glaciers in Greenland during the summer, which are hotspots for marine mammals, seabirds and fishes, but they did not know why narwhals have an affinity for these glaciers.

To better understand what glacier features narwhals prefer, Laidre and her colleagues used data from 15 narwhals outfitted with recorders that tracked each animal’s movements over four years in the 1990s and 2000s in Greenland’s Melville Bay, where narwhals congregate in summer. They combined this data with information about glaciers in Melville Bay over the same time period.

The researchers examined how narwhals behaved at the glaciers and collected information about each glacier’s physical properties to create models of narwhal behavior and tease out the animals’ preferences.

“Narwhals like slow-moving, big walls of ice where conditions are still and serene instead of a lot of runoff and disturbance,” Laidre said.

The researchers don’t know why the narwhals prefer these glaciers. They think the freshwater could shock small marine critters that are food for fish, which narwhals eat. Narwhals are also close relatives of beluga whales, which also seek out freshwater in summer to shed their skin, and it is possible there is something similar going on at the glacier front, Laidre said.

Laidre and her colleagues are performing additional research using a combination of moored instruments at glacier fronts, acoustic monitoring and land-based cameras to collect year-round data on narwhals to shed additional light on what physical properties of glacial fjords influence narwhal occurrence, relative abundance and acoustic behavior.

Laidre is also working on a project to use instrumented narwhals to examine the seafloor and measure ocean water temperatures. The research will help scientists better understand climate change in the high Arctic, Laidre said.

Narwhal, dolphin news


This video says about itself:

Listen to a narwhal’s resting heartbeat | Science News

7 December 2017

Narwhals have a resting heart rate of about 60 beats per minute. Now researchers have observed narwhals’ heart rate dropping precipitously low when diving to escape from humans. As melting sea ice opens up the Arctic to more human activity, the mammals, known as “unicorns of the sea” for their single tusk, may be more exposed to the potentially harmful escape response, scientists say.

Narwhals react to certain dangers in a really strange way. ‘Unicorns of the sea’ fleeing humans show the physiological signs of also being frozen in fear. By Mariah Quintanilla, 2:41pm, December 7, 2017.

This video says about itself:

Science News – Whales & Dolphins Have “Human-Like” Societies

19 October 2017

AI eavesdrops on dolphins and discovers six unknown click types. Computer program picked out the noises from underwater recordings of 52 million echolocation signals. By Maria Temming, 2:00pm, December 7, 2017.