This 25 May 2018 Dutch video shows four young thornback rays which had grown up in aquariums were freed into the Oosterschelde estuary in Zeeland province; to bring that species which had become extinct there, back.
See also here.
From the American Museum of Natural History in the USA:
First an alga, then a squid, enigmatic fossil is actually a fish
New study suggests that Cretaceous fossil discovered 70 years ago is a large ray
April 16, 2018
A fossil slab discovered in Kansas 70 years ago and twice misidentified — first as a green alga and then as a cephalopod —
Maybe misidentified a third time: as a Angiospermopsida seed plant
has been reinterpreted as the preserved remains of a large cartilaginous fish, the group that includes sharks and rays. In a study published in the Journal of Paleontology, American Museum of Natural History researchers describe the fishy characteristics of the animal, which lived between 70-85 million years ago.
“There are many examples of temporarily misplaced taxa in paleontological history, including ferns that were once thought to be sponges and lungfish teeth thought to be fungi“, said the lead author, Allison Bronson, a comparative biology Ph.D.-degree student in the Museum’s Richard Gilder Graduate School. “In this case, the misidentification didn’t happen because of a lack of technology at the time — scientists familiar with cartilage structure could easily see this was a chondrichthyan fish. The researchers used reasonable arguments for their interpretations, but didn’t look outside of their own fields.”
The enigmatic specimen, Platylithophycus cretaceum, is roughly 1.5-feet long by 10-inches wide and from the Niobrara Formation in Kansas. The Niobrara Formation is one of the most diverse fish-fossil sites in North America, preserving late Cretaceous animals that lived in and around the Western Interior Seaway, a broad expanse of water that split North America into two land masses.
In 1948, two paleobotanists from the Colorado School of Mines and Princeton University compared the texture of the fossil slab with that of green algae. They described two parts of a plant: surfaces covered with hexagonal plates, which they called “fronds”, and supposedly calcium carbonate-covered thread-like filaments. In 1968, two researchers from Fort Hays Kansas State College studying cephalopods from the Niobrara Formation compared the specimen with a cuttlefish, based primarily on its textural similarities to a cuttlebone — the unique internal shell of cuttlefish. The reclassification made Platylithophycus the oldest sepiid squid then on record.
In both of these earlier studies, the hard tissue was assumed to be composed of calcium carbonate, but no tests were performed. For the new study, Bronson and co-author John Maisey, a curator in the Museum’s Division of Paleontology, applied a small amount of dilute organic acid to the specimen — a method that has been widely used in paleontology since the time of the initial description of Platylithophycus. If there is a reaction, the fossilized material is likely made from calcium carbonate. But if there is no reaction, which was the case when Bronson and Maisey performed the test, it is likely made from calcium phosphate, as are the fossilized skeletons of cartilaginous fish like sharks and rays.
The most obvious clue that Platylithophycus was a cartilaginous fish are the hexagonal plates on the surface of the specimen. After taking a closer look with a scanning electron microscope, Bronson and Maisey reinterpreted that feature as tessellated calcified cartilage, found on both extinct and living sharks and rays. The new study suggests that the “filaments” earlier described are actually part of the gill arches, made up of tessellated cartilage. Gill arches are cartilaginous curved bars along the pharynx, or throat, that support the gills of fish. The “fronds” are reinterpreted as gill rakers, finger-like projections that extend from the gill arches and help with feeding.
“We think this was a rather large cartilaginous fish, possibly related to living filter-feeding rays such as Manta and Mobula“, Maisey said. “This potentially expands the range of diversity in the Niobrara fauna.”
But because this fossil only preserves the animal’s gills and no additional identifying features like teeth, it cannot be given a new name or reunited with an existing species. So until then, this fish will still carry the name of a plant.
This video says about itself:
Deep-Sea Skates Incubate Eggs Near Hydrothermal Vents | Nautilus Live
8 February 2018
In June 2015, a team of researchers aboard E/V Nautilus made a surprising discovery while exploring the seafloor northwest of the Galapagos Islands. Large numbers of skate egg cases were observed near hydrothermal vents emitting volcanically-heated fluids. Researchers believe the warmer water helps to incubate and speed development of the embryos–the first time this behavior has been observed in marine animals. The Bathyraja spinosissima, commonly known as Pacific white skate, is a relative of sharks and rays. As one of the deepest living skate species, this species is rarely seen but has been documented from the Galapagos Islands to the Pacific Northwest.
The research team from Charles Darwin Research Station, University of Rhode Island, and the Galapagos National Park Directorate collected video surveys and specimens using ROV Hercules, recently publishing their findings in Scientific Reports.
From Penn State university in the USA:
Deep-sea fish use hydrothermal vents to incubate eggs
February 12, 2018
Summary: An international team of researchers have discovered egg cases of deep-sea fish near hydrothermal vents. The team believes that deep-sea skates, a relative of sharks and rays, use the warm water near the vents to accelerate the typically years-long incubation time of their eggs.
Some deep-sea skates — cartilaginous fish related to rays and sharks — use volcanic heat emitted at hydrothermal vents to incubate their eggs, according to a new study in the journal Scientific Reports. Because deep-sea skates have some of the longest egg incubation times, estimated to last more than four years, the researchers believe the fish are using the hot vents to accelerate embryo development. This the first time such behavior has been seen in marine animals.
“Hydrothermal vents are extreme environments, and most animals that live there are highly evolved to live in this environment,” said Charles Fisher, Professor and Distinguished Senior Scholar of Biology at Penn State and an author of the paper. “This study is one of the few that demonstrates a direct link between the vent environment and animals that live most of their life elsewhere.”
Among the least explored and unique ecosystems, deep-sea hydrothermal fields are regions on the sea floor where hot water emerges after being heated in the ocean crust. In their study, an international team of researchers, led by Pelayo Salinas-de-León of the Charles Darwin Research Station, used a remotely operated underwater vehicle (ROV) to survey in and around an active hydrothermal field located in the Galapagos archipelago, 28 miles north of Darwin Island.
“The first place the ROV landed on the sea floor was on a ridge, in the plume of a nearby hydrothermal vent that we had specifically come to investigate — a black smoker,” said Fisher. “When we panned the camera down, we found something we did not expect: These giant egg cases, also known as mermaid purses. And we found several layers of them, indicating that whatever was laying these eggs had been coming back to this spot for many years to lay them. As the dive progressed, we saw more and more of these egg cases and realized that this was not the result of a single animal, but rather a behavior shared by many individuals.”
The researchers found 157 egg cases in the area and collected four with the ROV’s robotic arm. DNA analysis revealed that the egg cases belonged to the skate species Bathyraja spinosissima, one of the deepest-living species of skates that is not typically thought to occur near the vents. The majority — 58 percent — of the observed egg cases were found within about 65 feet of the chimney-like black smokers, the hottest kind of hydrothermal vents, and over 89 percent had been laid in places where the water was hotter than average. The researchers believe that the warmer temperatures in the area could reduce the typically years-long incubation time of the eggs.
While several species of reptiles and birds lay their eggs in locations that optimize soil temperatures, only two other groups of animals are known to use volcanically heated soils: the modern-day Polynesian megapode — a rare bird native to Tonga — and a group of nest-building neosauropod dinosaurs from the Cretaceous Period.
Because of their long lifespan and slow rate of development, deep-water skates may be particularly sensitive to threats to their environment, including fisheries expanding into deeper waters and sea-floor mining. Understanding the development and habitat of the skates is vital for developing effective conservation strategies for this poorly understood species.
“The deep sea is full of surprises,” said Fisher. “I’ve made hundreds of dives, both in person and virtually, to deep sea hydrothermal vents and have never seen anything like this.”
This video says about itself:
Manta Rays Use Tiny Fish to Help Them Stay Clean
12 January 2018
Wrasse perform a vital cleaning function for other fish, by ridding their bodies of dead cells and parasites. Their biggest customers–literally and figuratively–are the massive manta rays. From the series: David Attenborough’s Great Barrier Reef: Visitors.
This BBC video says about itself:
Filming Hundreds Of Mobula Rays At Night – Blue Planet II Behind The Scenes
The Blue Planet II underwater camera crew use new camera technology to film hundreds of Mobula rays in almost complete darkness. As the rays glide through the dark water, their movement causes plankton to glow which is picked up my the camera.
This video is called Thornback ray or thornback skate (Raja clavata).
On Saturday 14 October 2017, five young thornback rays, raised in aquariums, will be brought to an oyster farm in Yerseke town. There, they will get used to the Oosterschelde estuary water. In a few weeks’ time, they will be freed. Later, more, up to 1000, young thornback rays will be freed. It is hoped that they will be a sustainable thornback ray population in the Oosterschelde; where they had become extinct. This species is sexually mature after eight years. Will they survive now? We don’t know yet.
THis 2014 video from the USA says about itself:
In the front they are broad like a ray, but the back section they are all shark with dual dorsal fins. How cool is that! Also known as a bowmouth guitarfish, this large species can reach a length of 2.7 m (8.9 ft) and weigh up to 135 kg (298 lb).
WHERE TO SEE RAY SHARKS IN THE USA In one of the biggest resorts in town, there’s a major Aquarium with full grown Shark Rays in it. It’s called the “Shark Reef” and it’s main tank is filled with 1.3 million gallons of water. This Aquarium displays all kinds of sharks, rays, fish, reptiles, even a green sawtooth shark — but the real celebrities here are the Shark Rays….
Just step inside what they call the Shark Tunnel and within seconds you will have a very up close and personal encounter – guaranteed!
SHARK RAYS ARE A THREATENED SPECIES Shark Rays are not dangerous to humans. They like to eat crabs or lobsters and stuff like that but their numbers in the wild are dwindling due to overfishing. They are killed for the shark fin on top. It’s the main ingredient in Shark Fin Soup which is popular in certain parts of the world. Attempts to breed these amazing creatures in captivity so far has been a failure. Seven pups born at the Newport Aquarium in Kentucky all died within a few months of their birth.
From James Cook University in Australia:
Sharks and rays live a lot longer than we thought
September 29, 2017
A James Cook University researcher has found that sharks and rays live a lot longer than we thought — some twice as long as previously estimated.
Dr Alastair Harry looked at 53 different populations of sharks and rays that scientists had already intensely studied. He said in nearly a third of populations the studies had underestimated the animals’ ages.
“Questions arose over methods of ageing sharks after it was found that grey nurse sharks can live up to 40-years-old, double the length of time first thought, and the age of New Zealand porbeagle sharks had been underestimated by an average of 22 years,” he said.
Dr Harry said scientists usually measure shark age by counting growth rings in their vertebrae. These measurements are confirmed by tagging animals and injecting them with a fluorescent marker or by measuring carbon accumulated in the animals from atmospheric testing of nuclear weapons in the 1950s.
“Age underestimation appears to happen because the growth rings cease to form or become unreliable beyond a certain size or age. Across the cases I studied age was underestimated by an average of 18 years, and up to 34 years in one instance. From the amount of evidence we now have it looks like the problem is systemic rather than just a few isolated cases,” he said.
Dr Harry said accurate age estimation was important because it was used to manage fishery stocks.
He said the underestimation of longevity in orange roughy, a deep-sea fish, led to overly optimistic estimates of stock productivity, contributing to serious, long-term ecological and socio-economic impacts.
Dr Harry said sharks and rays are less commonly targeted by commercial fishers, but are still often caught as bycatch. That means the impacts of age underestimation may well take longer to become apparent.
“It could lead to inefficient prioritisation of research, monitoring and management measures. If it’s as widespread and common as it seems from this study, the impacts could also be substantial from a wider scientific perspective, affecting the many disciplines that also use baseline life history data,” he said.
To shine light on and conserve rare shark, ray, and chimaera species (chondrichthyans), SFU researchers have developed a fully-resolved family tree and ranked every species according to the unique evolutionary history they account for: here.