Sand tiger sharks protect small fish, video


This 14 July 2019 video from the USA says about itself:

In this excerpt from JONATHAN BIRD’S BLUE WORLD, Sand Tiger sharks become the unwitting bodyguards for school of small fish called scad on the wrecks of North Carolina.

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Spawning carp on video


This 2019 video is about spawning carp in the Oostvaardersplassen nature reserve in the Netherlands.

Jonathan van Deelen made this video.

African new deep-sea fish species discovered


This January 2019 video is called LiveAquaria® Diver’s Den® Deep Dive: Red Head Solon Fairy Wrasse (Cirrhilabrus solorensis).

Recently, relatives of that species were discovered.

From the California Academy of Sciences in the USA:

Wakanda forever! Scientists describe new species of ‘twilight zone’ fish from Africa

July 11, 2019

Africa has new purple-clad warriors more than 200 feet beneath the ocean’s surface. Deep-diving scientists from the California Academy of Sciences’ Hope for Reefs initiative and the University of Sydney spotted dazzling fairy wrasses — previously unknown to science — in the dimly lit mesophotic coral reefs of eastern Zanzibar, off the coast of Tanzania. The multicolored wrasses sport deep purple scales so pigmented, they even retain their color (which is typically lost) when preserved for research. The scientists name this “twilight zone” reef-dweller Cirrhilabrus wakanda (common name “Vibranium Fairy Wrasse”) in honor of the mythical nation of Wakanda from the Marvel Entertainment comics and movie Black Panther. The new fish is described today in ZooKeys.

“When we thought about the secretive and isolated nature of these unexplored African reefs, we knew we had to name this new species after Wakanda,” says Yi-Kai Tea, lead author and ichthyology PhD student from the University of Sydney. “We’ve known about other related fairy wrasses from the Indian Ocean, but always thought there was a missing species along the continent’s eastern edge. When I saw this amazing purple fish, I knew instantly we were dealing with the missing piece of the puzzle.”

Underwater Wakanda

The Academy scientists say Cirrhilabrus wakanda’s remote home in mesophotic coral reefs — below recreational diving limits — probably contributed to their long-hidden status in the shadows of the Indian Ocean. Hope for Reefs’ scientific divers are highly trained for the dangerous process of researching in these deep, little-known mesophotic reefs, located 200 to 500 feet beneath the ocean’s surface. Accessing them requires technical equipment and physically intense training well beyond that of shallow-water diving. The team’s special diving gear (known as closed-circuit rebreathers) includes multiple tanks with custom gas blends and electronic monitoring equipment that allow the divers to explore deep reefs for mere minutes before a lengthy, hours-long ascent to the surface.

“Preparation for these deep dives is very intense and our dive gear often weighs more than us,” says Dr. Luiz Rocha, Academy Curator of Fishes and co-leader of the Hope for Reefs initiative. “When we reach these reefs and find unknown species as spectacular as this fairy wrasse, it feels like our hard work is paying off.”

Using a microscope, the team examined the specimens’ scales, fin rays, and body structures. DNA and morphological analyses revealed the new fairy wrasse to be different from the other seven species in the western Indian Ocean as well as other relatives in the Pacific. The new species’ common name is inspired by the fictional metal vibranium, a rare, and, according to Rocha, “totally awesome” substance found in the Black Panther nation of Wakanda. The Vibranium Fairy Wrasse’s purple chain-link scale pattern reminded the scientists of Black Panther’s super-strong suit and the fabric motifs worn by Wakandans in the hit film.

Precious life in deep reefs

In a recent landmark paper, the Academy team found that twilight zone reefs are unique ecosystems bursting with life and are just as vulnerable to human threats as their shallow counterparts. Their findings upended the long-standing assumption that species might avoid human-related stressors on those deeper reefs. The Hope for Reefs team will continue to visit and study twilight zone sites around the world to shed light on these often-overlooked ecosystems.

In addition to this new fish from Zanzibar, Rocha and his colleagues recently published descriptions of mesophotic fish from Rapa Nui [Easter Island] and Micronesia. Luzonichthys kiomeamea is an orange, white, and sunny yellow dwarf anthias endemic to Rapa Nui, and the basslet Liopropoma incandescens (another new species published today in Zookeys) inhabits Pohnpei‘s deep reefs — a neon orange and yellow specimen collected from a rocky slope 426 feet beneath the ocean’s surface.

“It’s a time of global crisis for coral reefs, and exploring little-known habitats and the life they support is now more important than ever,” says Rocha. “Because they are out of sight, these deeper reefs are often left out of marine reserves, so we hope our discoveries inspire their protection.”

How bluehead wrasse fish change sex


This 2008 video says about itself:

Caribbean Fish Identification: Bluehead Wrasse

Bluehead Wrasse fish experience a variety of color changes and are difficult to identify. Learn to identify Bluehead Wrasse with tips from a Caribbean scuba instructor in this free tropical fish identification video.

Expert: Don Stark.

Bio: Don Stark has over 20 years of active diving experience. He has been a frequent participant on fish collecting expeditions in the Bahamas with New England Aquarium staff.

Filmmaker: Don Stark.

From the La Trobe University in Australia:

Secrets of a sex-changing fish revealed

July 10, 2019

We may take it for granted that the sex of an animal is established at birth and doesn’t change.

However, about 500 species of fish change sex in adulthood, often in response to environmental cues. How these fish change sex has, until now, been a mystery.

The secrets of fish that change sex have, for the first time, been revealed by an international collaboration led by New Zealand scientists and including La Trobe University geneticist and Prime Minister’s Prize for Science winner 2017, Professor Jenny Graves. The findings were published today in the journal Science Advances.

“I’ve followed the bluehead wrasse for years because sex change is so quick and is triggered by a visual cue,” Professor Graves said.

“How sex can reverse so spectacularly has been a mystery for decades. The genes haven’t changed, so it must be the signals that turn them off and on.”

Bluehead wrasses live in groups, on coral reefs of the Caribbean. A dominant male — with a blue head — protects a harem of yellow females. If the male is removed, the biggest female becomes male — in just 10 days. She changes her behaviour in minutes, her colour in hours. Her ovary becomes a testis and by 10 days it is making sperm.

Using the latest genetic approaches — high-throughput RNA-sequencing and epigenetic analyses — the researchers discovered when and how specific genes are turned off and on in the brain and gonad so that sex change can occur.

The study is important for understanding how genes get turned off and on during development in all animals (including humans), and how the environment can influence this process.

“We found that sex change involves a complete genetic rewiring of the gonad,” Dr Erica Todd from the University of Otago, the co-lead author, said.

“Genes needed to maintain the ovary are first turned off, and then a new genetic pathway is steadily turned on to promote testis formation.”

Co-lead author PhD candidate Oscar Ortega-Recalde, also from the University of Otago, said the amazing transformation also appears possible through changes in cellular “memory”.

“Chemical markers on DNA control gene expression and to help cells remember their specific function in the body. Our study is important because it shows that sex change involves profound changes in these chemical marks,” Mr Ortega-Recalde said.

La Trobe’s Professor Jenny Graves said the project links to studies of sex reversal in Australian dragon lizards that she is collaborating on with researchers at the University of Canberra.

“With dragon lizards the trigger for sex change is temperature, which overrides genes on the male sex chromosomes and causes embryos to develop as females,” Professor Graves said.

“Sex reversal in dragons and the wrasse involve some of the same genes, so I think we are looking at an ancient system for environmental control of gene activity.”

Sea lamprey love life, new research


This 12 April 2018 video from Wales is called Sea lampreys (Petromyzon marinus) spawning in the upper Wye.

From Michigan State University in the USA:

Smells like love…to sea lampreys

July 9, 2019

Some people are drawn to cologne; others are attracted to perfume. When it comes to sea lampreys, however, spermine smells like love.

In new research led by Michigan State University and published in the current issue of PLoS Biology, spermine, an odorous compound found in male semen, proved to be a powerful aphrodisiac.

Spermine isn’t a new discovery. It’s been a known quantity in semen since 1678 — at least in humans. Its tractor-beam effect on spawning female sea lampreys is new, however, and it can be yet another key way to potentially control the invasive species.

“We found the male ejaculate contains spermine, a highly specific and potent pheromone, which attracts only mature females”, said Weiming Li, fisheries and wildlife professor and senior author of the study. “Mature females likely use spermine to identify males actively releasing sperm in the spawning aggregation.”

They need this help because sea lampreys migrate up to river gravel beds ¬- spawning aggregation sites — drawn by other pheromones released from spawning males. These mating cues are merely the billboards, though, along riverine highways that draw them to the sites.

Arriving at the gravel bar of love, the females see many males on nests — all mature and ready to mate. Rather than find “the perfect mate,” the females seem to act on localized cues and form promiscuous pairs with many males — in sequence and one at a time — and spawn several times per hour.

Spermine is a coup de gras [sic; coup de grâce] that helps females make their final selections, navigate the throng of males and find the best ones with which to mate. According to Li, this is the first time scientists have been able to document this behavior in sea lampreys.

“We also were able to document a specific receptor in the noses of females that picks up spermine, and it can be smelled at trace-level concentrations,” said Richard Neubig, pharmacology professor and study co-author. “This was a big job requiring nearly 12,000 tests in the MSU high-throughput screening lab to figure out the right pair of chemical and receptor.”

Ovulatory females detect this faint cologne, and they respond at levels as low as 10-14 molar, a mere whiff comparable to a single drop of perfume in a pool. It’s interesting to note that even higher levels of spermine had no effect on immature females or other males.

Li and a team of scientists identified the receptor for spermine, a trace-associated receptor, or TAAR, in females. Future work will determine if spermine can be used to manage invasive sea lamprey populations. Likewise, MSU scientists will investigate the TAAR mechanism to explore its control potential.

Controlling sea lampreys in the Great Lakes is a critical goal of fisheries scientists. The invasive species infiltrated the upper Great Lakes via the Atlantic Ocean in the 1920s through shipping canals. They feed by attaching themselves to other fish, such as salmon and trout. One sea lamprey can kill more than 40 pounds of fish, and the U.S. and Canadian governments spend approximately $20 million annually to control them in the Great Lakes.

Great white sharks’ small Jurassic ancestor


This 23 July 2018 video says about itself:

In the first video of this year’s Shark Week we investigate the earliest evolution of the sharks, and look at just where and when these incredibly remarkable animals came from.

From the University of Vienna in Austria:

The ancestor of the great white shark

The unique tooth structure of the great white shark gives new insights into its origin

July 8, 2019

Mackerel sharks (Lamniformes) are a group consisting of some of the most iconic sharks we know, including the mako shark (the fastest shark in the world), the infamous great white shark and Megalodon, the biggest predatory shark that has ever roamed the world’s oceans. An international team of researchers around Patrick L. Jambura from the University of Vienna found a unique feature in the teeth of these apex predators, which allowed them to trace back the origin of this group to a small benthic shark from the Middle Jurassic (165 mya). Their study was recently published in the journal Scientific Reports.

Similar to humans, shark teeth are composed of two mineralized structures: a hard shell of hypermineralized tissue (in humans enamel, in sharks enameloid) and a dentine core. Depending on the structure of the dentine we distinguish between two different types: orthodentine and osteodentine.

Orthodentine has a very compact appearance and is similar to the dentine we can find in human teeth. In shark teeth, orthodentine is confined to the tooth crown. In contrast, the other dentine type is spongious in appearance and resembles real bone and therefore is called osteodentine. It can be found in the root, anchoring the tooth to the jaw and in some species also in the tooth crown where it supports the orthodentine.

Using high resolution CT scans, Patrick L. Jambura and his colleagues examined the tooth composition of the great white shark and its relatives and found a peculiar condition of the teeth of members of this group: the osteodentine of the roots intrudes into the crown and replaces the orthodentine there completely, making it the only type of dentine being present. This condition is not known from any other shark, which all possess orthodentine to some degree and thus it is confined to members of this group.

Another species that was examined was the fossil shark Palaeocarcharias stromeri, which is well-represented by complete skeletons from the famous 150 million-year-old Solnhofen Plattenkalks of South Germany. The oldest find of this species is from the Middle Jurassic (165 million years ago) and it didn’t have much in common with today’s mackerel sharks. Palaeocarcharias was a small sluggish benthic shark, not exceeding lengths of more than a metre and seemingly hunted small fish in shallow waters. To this day, its affiliation has been a riddle to scientists, since its body shape resembles a carpet shark, while its fang like teeth are similar to mackerel sharks. The examination of the tooth microstructure yielded the presence of the same unique tooth composition that is found only in great white sharks and their relatives. The shared tooth histology is a strong indicator that this small inconspicuous shark gave rise to one of the most iconic shark lineages that includes giants like the extinct Megalodon or the living great white shark.

“Orthodentine is known for almost all vertebrates — from fish to mammals, including all modern sharks, except for the mackerel sharks. The discovery of this unique tooth structure in the fossil shark Palaeocarcharias strongly indicates that we found the oldest known ancestor of the great white shark and shows that even this charismatic giant shark started on a shoestring” states Patrick L. Jambura.

Plastic kills sharks, rays


This 2016 video is called The Secret World of Sharks and Rays (Nature Documentary).

From the University of Exeter in England:

Hundreds of sharks and rays tangled in plastic

July 4, 2019

Hundreds of sharks and rays have become tangled in plastic waste in the world’s oceans, new research shows.

University of Exeter scientists scoured existing published studies and Twitter for shark and ray entanglements, and found reports of more than 1,000 entangled individuals.

And they say the true number is likely to be far higher, as few studies have focussed on plastic entanglement among shark[s] and rays.

The study says such entanglement — mostly involving lost or discarded fishing gear — is a “far lesser threat” to sharks and rays than commercial fishing, but the suffering it causes is a major animal welfare concern.

“One example in the study is a shortfin mako shark with fishing rope wrapped tightly around it,” said Kristian Parton, of the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall.

“The shark had clearly continued growing after becoming entangled, so the rope — which was covered in barnacles — had dug into its skin and damaged its spine.

“Although we don’t think entanglement is a major threat to the future of sharks and rays, it’s important to understand the range of threats facing these species, which are among the most threatened in the oceans.

“Additionally, there’s a real animal welfare issue because entanglements can cause pain, suffering and even death.”

Co-author Professor Brendan Godley, co-ordinator of the university’s marine strategy, added: “Due to the threats of direct over-fishing of sharks and rays, and ‘bycatch‘ (accidental catching while fishing for other species), the issue of entanglement has perhaps gone a little under the radar.

“We set out to remedy this. Our study was the first to use Twitter to gather such data, and our results from the social media site revealed entanglements of species — and in places — not recorded in the academic papers.”

The review of academic papers found reports of 557 sharks and rays entangled in plastic, spanning 34 species in oceans including the Atlantic, Pacific and Indian. Almost 60% of these animals were either lesser spotted dogfish, spotted ratfish or spiny dogfish.

On Twitter, the researchers found 74 entanglement reports involving 559 individual sharks and rays from 26 species including whale sharks, great whites, tiger sharks and basking sharks.

Both data sources suggested “ghost” fishing gear (nets, lines and other equipment lost or abandoned) were by far the most common entangling objects. Other items included strapping bands used in packaging, polythene bags and rubber tyres.

The study identified factors that appear to put certain species more at risk:

  • Habitat — sharks and rays in the open ocean appear more likely to get entangled, as do those living on the sea floor, where materials such as nets loaded with dead fish sink and attract predators, which in turn get stuck.
  • Migration — species that cover long distances appear at more at risk of encountering plastic waste.
  • Body shape — sharks seem to be at greater risk than rays. Species with unusual features — such as manta rays, basking sharks and sawfish — are also at more risk.

U.S. NAMED ONE OF WORST TRASH OFFENDERS The U.S. is one of the world’s top offenders when it comes to its creation and management of solid waste, according to an alarming new study. The report found that the U.S. produces 12% of global municipal solid waste, despite it representing just 4% of the world’s population. [HuffPost]