Red Sea coral reef wildlife, video


This video says about itself:

The Incredible Sea Life of the Red Sea Coral Reef | BBC Earth

Simon Reeve dives into the Red Sea to get close to its incredible fish and marine wildlife.

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Extinct Megalodon sharks’ teeth, new study


This 26 August 2018 video says about itself:

Did They Find a Living Megalodon In the Mariana Trench?

Сould Megalodon sharks still be alive in the deepest parts of the ocean? Science tells us that Megalodon sharks are extinct. Given that it was a massive shark with noticeable feeding habits, we guess that if Megalodon sharks were still roaming the oceans, they would probably have been spotted by someone by now.

From the Florida Museum of Natural History in the USA:

How megalodon‘s teeth evolved into the ‘ultimate cutting tools’

March 4, 2019

Megalodon, the largest shark that ever lived, is known only from its gigantic bladelike teeth, which can be more than 7 inches long. But these teeth, described by some scientists as the “ultimate cutting tools”, took millions of years to evolve into their final, iconic form.

Megalodon’s earliest ancestor, Otodus obliquus, sported three-pronged teeth that could have acted like a fork for grasping and tearing fast-moving fishes. In later megatooth shark species, teeth flattened and developed serrated edges, transitioning to a knifelike shape for killing and eating fleshy animals like whales and dolphins.

But the final tooth evolution in this lineage of powerful predators still took 12 million years, a new study shows. An analysis of teeth from megalodon and its immediate ancestor, Carcharocles chubutensis, traced the unusually slow, gradual shift from a large tooth flanked by mini-teeth — known as lateral cusplets — to teeth without these structures.

“This transition was a very long, drawn-out process, eventually resulting in the perfect cutting tool — a broad, flat tooth with uniform serrations”, said study lead author Victor Perez, a doctoral student in geology at the Florida Museum of Natural History. “It’s not yet clear why this process took millions of years and why this feature was lost.”

Teeth can offer a wealth of information about an animal, including clues about its age, when it lived, its diet and whether it had certain diseases. Megalodon‘s teeth suggest its hunting style was likely a single-strike tactic, designed to immobilize its prey and allow it to bleed out, Perez said.

“It would just become scavenging after that,” he said. “A shark wouldn’t want to grab and hold onto a whale because it’s going to thrash about and possibly injure the shark in the process.”

Perez and his collaborators carried out a “census of teeth”, analyzing 359 fossils with precise location information from the Calvert Cliffs on the western shore of Maryland’s Chesapeake Bay — an ocean in C. chubutensis and megalodon’s day. The cliffs provide an uninterrupted rock record from about 20 to 7.6 million years ago, a period that overlaps with these megatooth sharks.

The researchers noted a consistent decrease in the number of teeth with lateral cusplets over this timespan. About 87 percent of teeth from 20 to 17 million years ago had cusplets, falling to about 33 percent roughly 14.5 million years ago. By 7.6 million years, no fossil teeth had cusplets.

Adult C. chubutensis had cusplets while adult megalodon did not, but this feature is not a reliable identifier of which species a tooth belonged to, Perez said. Juvenile megalodon could have cusplets, making it impossible to discern whether a tooth with cusplets came from C. chubutensis or a young megalodon.

Some teeth analyzed for the study had tiny bumps or pronounced serrations where cusplets would be. A set of teeth from a single shark had cusplets on some, no cusplets on others and replacement teeth with reduced cusplets.

This is why paleontologists cannot pinpoint exactly when megalodon originated or when C. chubutensis went extinct, said Perez, who began the project as an intern at the Calvert Marine Museum.

“As paleontologists, we can’t look at DNA to tell us what is a distinct species. We have to make distinctions based off of physical characteristics,” he said. “We feel it’s impossible to make a clean distinction between these two species of sharks. In this study, we just focused on the evolution of this single trait over time.”

Lateral cusplets may have been used to grasp prey, Perez said, which could explain why they disappeared as these sharks shifted to a cutting style of feeding. Another possible function was preventing food from getting stuck between the sharks’ teeth, which could lead to gum disease. But if the cusplets served a purpose, why lose them?

“It’s still a mystery,” he said. “We’re wondering if something was tweaked in the genetic pathway of tooth development.”

Perez’s fascination with fossil sharks started at age 6 when he visited the Calvert Marine Museum.

“I got to take a shark tooth home from a discovery box. That set me off on the whole career path of studying fossils,” he said.

That first tooth spawned an obsession in Perez, who lived about an hour from the Calvert Cliffs. On family trips to the beaches on the north end of the cliffs, he spent his time combing the area for shark teeth.

“That was the only thing I wanted to do,” he said. “On a typical trip, I would leave with an average of 300 teeth.”

For this study, he relied on the efforts of fellow beachcombers: The vast majority of teeth analyzed in the study were discovered by amateur fossil collectors and donated to museum collections.

“This study is almost entirely built on the contributions of amateur, avocational paleontologists,” he said. “They are a valuable part of research.”

Extinct Cayman Islands mammals discovery


This 8 May 2015 video says about itself:

Arrow Blenny comes back from the verge of extinction in the Cayman Islands

Video of an Arrow Blenny on Little Cayman May 2015. The Arrow Blenny was almost extinct in the Cayman Islands at the height of the lionfish invasion several years ago and has made a comeback due to the efforts of regular community culling of the invasive lionfish. The first sighting of an Arrow Blenny on Little Cayman since its demise was in June 2014. They are being sighted more frequently now … This video was shot by Carl Arnoult.

From the Zoological Society of London in England:

Ancient mammal remains digested by [Cuban] crocodiles reveal new species

Cayman Island fossils reveal previously undescribed extinct mammals

March 4, 2019

Fossilised bones that appear to have been digested by crocodiles in the Cayman Islands have revealed three new species and subspecies of mammal that roamed the island more than 300 years ago.

An expert team led by international conservation charity ZSL (Zoological Society of London), the American Museum of Natural History, and the New Mexico Museum of Natural History studied the bones from collections in British and American museums including the Florida Museum of Natural History at the University of Florida. The bones had been previously collected from caves, sinkholes and peat deposits on the Cayman Islands between the 1930s and 1990s.

Published in the Bulletin of the American Museum of Natural History today (March 4, 2019), the team describe two new large rodents (Capromys pilorides lewisi and Geocapromys caymanensis), as well as a small shrew-like mammal named Nesophontes hemicingulus. Fossil remains of the land mammal have been previously reported from the Cayman Islands, but have not been scientifically described until now.

The three mammals were unique to the Cayman Islands, existing nowhere else in the world. The scientists calculated that they would have probably become extinct around the 1700s, likely due to the arrival of European settlers and introduced mammals such as rats, cats and dogs.

Professor Samuel Turvey, Senior Research Fellow at ZSL’s Institute of Zoology, and co-author of the paper, said: “Humans are almost certainly to blame for the extinction of these newly described mammals, and this represents just the tip of the iceberg for mammal extinctions in the Caribbean. Nearly all the mammal species that used to live on these tropical islands, including all of the native Caribbean sloths and monkeys, have recently disappeared.

“It’s vitally important to understand the factors responsible for past extinctions of island species, as many threatened species today are found on islands. The handful of Caribbean mammals that still exist today are the last survivors of a unique vanished world and represent some of the world’s top conservation priorities.”

Animals described as “coneys” and “little beasts like cats”, which were probably the now-extinct rodents Capromys or Geocapromys, were seen and recorded by Sir Francis Drake when he visited the Cayman Islands in 1586. Despite the major marine barrier separating the Cayman Islands from other Caribbean lands, the extinct mammals described in this study are similar to those on Cuba, and other subspecies of Capromys pilorides still survive on Cuba today. The Cayman Islands may have originally been colonised by mammals carried across from Cuba on floating rafts of vegetation, which in some cases have been documented to float as far as 100 kilometres in less than a week.

Professor Ross MacPhee of the American Museum of Natural History’s Mammalogy Department, a co-author of the study, said: “Although one would think that the greatest days of biological field discoveries are long over, that’s very far from the case. With only one possible sighting early in the course of European expansion into the New World, these small mammals from the Cayman Islands were complete unknowns until their fossils were discovered. Their closest relatives are Cuban; how and when did they manage a 250-km journey over open water?”

The Cayman Islands

The Cayman Islands consist of three islands (Grand Cayman, Little Cayman and Cayman Brac) in the north-western Caribbean Sea, separated by significant deeps of nearly 2000m of water for more than 20 million years.

Though it is rare that islands are successfully colonised by mammals other than bats, this is not the case for the West Indies — or the islands of the Caribbean Basin. During the late Quaternary record (i.e., 0.5-1.0 million years ago) the islands comprised of nearly 130 different species, including sloths, insect eating mammals, ancient mysterious monkeys, rodents and bats.

However, due to the arrival of European humans, only 13 endemic mammal species now survive in the West Indies, along with 60 species of bat. Calculations from the study indicate that several species might have survived into present day if they had not suffered at the hands of man — altering their habitat and introducing exotic creatures over the last 500 years.

Japanese eels, new research


This 2015 video is called The Mystery of the Eel – Documentary Film.

From Kobe University in Japan:

Endangered eel located using DNA from one liter of water

March 1, 2019

Researchers have shed light on the distribution of Japanese eel by analyzing environmental DNA (eDNA) from small samples of river water. This could enable faster and more effective surveys of Japanese eel populations, and help to conserve this endangered species. The finding was published on February 27 in Aquatic Conservation: Marine and Freshwater Ecosystems.

Eels are migratory fish that spawn in the ocean and grow up along the coast and in rivers. There are 16 known species in the world, distributed in 150 countries. The Japanese eel (Anguilla japonica) is found across East Asia. Since ancient times it has been an important part of Japanese life: as a food source, a subject of traditional poems and art, and sometimes even as a target of worship. However, eel catches have fallen drastically since the 1970s, and in 2014 it was added to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.

Most river surveys of Japanese eel use electrofishing. However, this method requires a lot of time and resources, and for widely distributed species it may not collect enough data. Surveys are usually carried out in the daytime, while the nocturnal eels hide among vegetation and dirt.

Rapidly-advancing eDNA technology can monitor aquatic lifeforms through extraction and analysis of DNA present in water, without capturing the organisms themselves. In this study, the team investigated whether eDNA analysis could be used to show the distribution of Japanese eel. They collected 1-liter samples from 125 locations upstream and downstream in 10 rivers in Japan, and analyzed the eDNA from these samples using a Real-Time PCR system. At the same time they carried out an electrofishing survey in the same locations, and compared this with the eDNA analysis results.

Japanese eel eDNA was found in 91.8% of the locations where eel had been confirmed using electrofishing (56 of 61 locations), and eDNA was also detected in an additional 35 areas (mainly upstream) where eel individuals were not found. This shows that eDNA analysis is more sensitive than conventional surveys for detecting the presence of Japanese eel in rivers. Electrofishing data for eel numbers and biomass also positively correlated with eDNA concentrations, showing that eDNA could help us estimate the abundance and biomass of Japanese eel.

In this study, electrofishing required three or more people for each river and took at least three days. Collecting water samples for eDNA analysis only needed two people, took half a day at the most, and data processing was finished by one person in one and a half days. When carrying out a large-scale distribution survey the eDNA analysis method is better in terms of human and time resources.

This method could potentially survey populations on an even wider scale. It is non-lethal, making it ideal for monitoring endangered species. The team is currently using eDNA analysis to monitor eels in Japan and overseas: it can be used as an international unified method for widely-distributed species. This could be a great help in the conservation and sustainable use of eel species worldwide.

The eDNA analysis method is also effective in dealing with the invasion of foreign eel species. For 20 years there have been reports of foreign eels (European eels and American eels) being released into Japanese waterways. These species look the same as Japanese eel, making them hard to detect. They are also long-lived so they may impact the ecosystem over long periods of time. By carrying out a wide-ranging investigation using eDNA analysis, we can swiftly identify foreign eel species and their distribution.

This study was carried out by Research Associate Hikaru Itakura (Kobe University Graduate School of Science), Assistant Professor Ryoshiro Wakiya (Chuo University), Assistant Professor Satoshi Yamamoto (Kyoto University), Associate Professor Kenzo Kaifu (Chuo University), Associate Professor Takuya Sato and Associate Professor Toshifumi Minamoto (both from Kobe University).

Itakura comments: “Concentration of eDNA in rivers is influenced by physical properties such as water depth and the speed of the current. Next we must increase the accuracy of eDNA analysis by clarifying the impact of these physical properties on eDNA concentration.”

Swiss Triassic fossil fish, new study


Fossil Fish Eosemionotus diskosomus. Credit: A. López-Arbarello

From the Ludwig-Maximilians-Universität München in Germany:

Paleontology: Diversification after mass extinction

March 1, 2019

A team led by Ludwig-Maximilians-Universitaet (LMU) in Munich paleontologist Adriana López-Arbarello has identified three hitherto unknown fossil fish species in the Swiss Alps, which provide new insights into the diversification of the genus Eosemionotus.

Monte San Giorgio in the Swiss canton of Ticino is one of the most important known sources of marine fossils from the Middle Triassic Period (around 240 million years ago). The new and exquisitely preserved fossil fish specimens, which Dr. Adriana López-Arbarello (a member of the Institute of Paleontology and Geobiology and of the Geobiocenter at LMU) has been studying in collaboration with colleagues based in Switzerland were also discovered in these dolomites and limestones. As the researchers now report in the online journal Palaeontologia Electronica, the specimens represent three previously unknown species of Eosemionotus, a genus of ray-finned fishes. “The largest episode of mass extinction in the history of the Earth took place about 250 million years ago,” as López-Arbarello explains. “Our finds now provide further evidence that after this catastrophic event, the biosphere recovered relatively fast and went through a period of rapid diversification and the emergence of numerous new species during the Middle Triassic.”

The first member of the genus Eosemionotus was discovered in the vicinity of Berlin in 1906, and was named E. vogeli. Almost a century later, in 2004, a second species was described from Monte San Giorgio as E. ceresiensis. Detailed anatomical studies of new material from this locality, carried out by López-Arbarello, have now enabled the recognition of three further species that can be assigned to same genus — E. diskosomus, E. sceltrichensis and E. minutus. All five species are small in size, but they can be clearly distinguished from each other on the basis of the relative proportions of their bodies, the position of the fins, the morphology of the skull, and the disposition of teeth and scales. “These differences indicate that each species was adapted to different ecological niches,” López-Arbarello concludes.

These findings provide new insights into the evolution of the genus. “Our phylogenetic analyses demonstrate that Eosemionotus is the oldest known member of an extinct family within the Order Semionotiformes. Although the Semionotiformes were a species-rich and highly diversified clade during the Mesozoic Era, the order died out in the Cretaceous. Only a few members of its sister group have survived down to the present day, and this ancient lineage is now represented by a single family, the gars,” says López-Arbarello.

Fossil sharks, rays discovery in Madagascar


Eocene shark teeth from northwestern Madagascar. Credit: Samonds et al, 2019

From PLOS:

A rare assemblage of sharks and rays from nearshore environments of Eocene Madagascar

This finding, including one new shark species, fills a gap in the known marine record of Madagascar

February 27, 2019

Eocene-aged sediments of Madagascar contain a previously unknown fauna of sharks and rays, according to a study released February 27, 2019 in the open-access journal PLOS ONE by Karen Samonds of Northern Illinois University and colleagues. This newly-described fauna is the first report of sharks and rays of this age in Madagascar.

The Mahajanga basin of northwestern Madagascar yields abundant fossil remains of terrestrial and marine ecosystems, but little is known about fossil sharks and rays during the Eocene Epoch, 55-34 million years ago, in this region. This is in contrast to the numerous shark and ray faunas known from other Eocene sites around the globe, and to shark and ray ecosystems known from older and younger sediments in the Mahajanga basin.

In this study, Samonds and colleagues collected isolated teeth, dental plates, and stingray spines from ancient coastal sediments of the Ampazony and Katsepy regions of the basin, dated to the middle to late Eocene. They identified at least 10 species of sharks and rays, including one new species, Carcharhinus underwoodi. This is the oldest named species of Carcharhinus, a genus that has been globally distributed for the past 35 million years but is known only rarely from the Eocene.

Aside from the new species, the fauna of Eocene Madagascar shares many species with Eocene ecosystems across North Africa, suggesting these animals were widespread in southern seas at that time. On the other hand, the Madagascar fauna is uniquely lacking in sandsharks and dominated by eagle rays, indicating a somewhat unusual ecosystem, unsurprising given Madagascar’s long history of isolation. The authors caution that this study provides an incomplete picture given that they collected only fossils larger than 2 millimeters. They recommend that future studies target smaller material for a more complete view of the ancient ecosystem.

Sturgeon in trouble, video


This 20 February 2019 video from North America says about itself:

This Ancient Fish is Facing a Plummeting Population Crisis

Despite producing thousands of eggs at a time, sturgeon populations are down to about 1% of their historic population levels. Scientists are scrambling for answers.