New shark species discovery


This 2015 video from the USA is called Eugenie Clark – The Shark Lady.

From the Florida Institute of Technology in the USA:

Newly discovered shark species honors female pioneer

Squalus clarkae named for Eugenie Clark

July 17, 2018

Eugenie Clark was a pioneer in shark biology, known around the world for her illuminating research on shark behavior. But she was a pioneer in another critical way, as one of the first women of prominence in the male-dominated field of marine biology.

Fondly labeled the “Shark Lady”, Clark, who founded Mote Marine Laboratory and continued studying fishes until she passed away in 2015 at age 92, will now be recognized with another distinction: namesake of a newly discovered species of dogfish shark.

The species, named Squalus clarkae, also known as Genie’s Dogfish, was identified from the Gulf of Mexico and western Atlantic Ocean. The confirmation of this new species was reported this month in the journal Zootaxa.

Florida Institute of Technology assistant professor and shark biologist Toby Daly-Engel was among the paper’s four authors, along with marine scientists Mariah Pfleger of Oceana, the lead author and Daly-Engel’s former graduate student, and Florida State University’s Dean Grubbs and Chip Cotton.

Before their findings, researchers labeled this species of dogfish shark Squalus mitsukurii. However, using new genetic testing and morphology, the study of an organism through physical appearance, they discovered and classified Genie’s Dogfish as a new species.

Deep-sea sharks are all shaped by similar evolutionary pressure, so they end up looking a lot alike,” Daly-Engel said. “So we rely on DNA to tell us how long a species has been on its own, evolutionarily, and how different it is.”

“This type of research is essential to the conservation and management of sharks, which currently face a multitude of threats, from overfishing and bycatch, to the global shark fin trade“, added Pfleger, marine scientist for the responsible fishing and sharks campaigns at Oceana. “Many fisheries around the world are starting to fish in deeper and deeper waters and unfortunately, much less is known about many of the creatures that live in the deep. The first step to successfully conserving these species that live in deeper waters, like Genie’s Dogfish, is finding out what is down there in the first place.”

For Daly-Engel, the discovery goes beyond science.

At an early age, she was drawn to Clark and her books. As Daly-Engel advanced in her career, she saw Clark’s impact as one of the early members of the American Elasmobranch Society, a group Daly-Engel later joined and through which she met Clark.

“She is the mother of us all”, Daly-Engel said. “She was not just the first female shark biologist, she was one of the first people to study sharks.”

The feeling rings true for Pfleger, as well. “Dr. Clark was a trailblazer for women in shark biology. Her work showed me that it was possible to make my mark in a male-dominated field. This paper is a perfect example of how her career has influenced multiple generations of women in science: the first author is a woman who graduated from a woman-led lab.”

“Genie was aptly nicknamed the ‘Shark Lady’ because her shark research was so innovative and she was dedicated to teaching the truth about sharks“, said Robert Hueter, Ph.D., director of the Center for Shark Research at Mote. “Not only was she responsible for establishing Mote’s legacy of more than 60 years in shark research, but also, her discoveries inspired people around the world to develop a sense of eagerness and passion for understanding and ultimately protecting these fascinating animals.”

As founding director of Mote Marine Laboratory, Clark was very familiar with the Gulf of Mexico. For a trailblazer in the world of shark biology, it is fitting that the new species of shark would be named after her, Daly-Engel said.

“Genie established Mote and she lived on the Gulf of Mexico coast,” she said. “She did a lot to advance our understanding of marine biodiversity there. So naming the dogfish shark from the Gulf of Mexico after her is the most appropriate thing in the world.”

About Eugenie Clark

Eugenie Clark, an ichthyologist, was a world authority on fishes — particularly sharks and tropical sand fishes. A courageous diver and explorer, Clark conducted 72 submersible dives as deep as 12,000 feet and led over 200 field research expeditions to the Red Sea, Gulf of Aqaba, Caribbean, Mexico, Japan, Palau, Papua New Guinea, the Solomon Islands, Thailand, Indonesia and Borneo to study sand fishes, whale sharks, deep sea sharks and spotted oceanic triggerfish. In 1955, Clark started the one-room Cape Haze Marine Laboratory in Placida, Fla., with her fisherman assistant and with philanthropic support and encouragement from the Vanderbilt family. That lab became Mote Marine Laboratory in 1967 to honor major benefactor William R. Mote. Today, Mote is based on City Island, Sarasota, and it hosts more than 20 diverse research and conservation programs along with extensive informal science education programs.

Advertisements

Fish scales, ancestors of hair, feathers


This music video from Europe says about itself:

Animal body coverings song

9 January 2016

Simple video used to teach students who are ELLs [Euroleague for Life Sciences] about different animal body coverings: feathers, skin, scales, or fur.

Music taken from Dommo107/Universal Music Corporation.

From the University of Virginia in the USA:

The ancient armor of fish — scales — provide clues to hair, feather development

July 17, 2018

Summary: How do scale patterns on fish provide understanding of the development of feathers, fur — and even cancer? Biologists are investigating.

When sea creatures first began crawling and slithering onto land about 385 million years ago, they carried with them their body armor: scales. Fossil evidence shows that the earliest land animals retained scales as a protective feature as they evolved to flourish on terra firma.

But as time passed, and species diversified, animals began to shed the heavy scales from their ocean heritage and replace them with fur, hair and feathers.

Today the molecular mechanisms of scale development in fish remain remarkably similar to the mechanisms that also produce feathers on birds, fur on dogs and hair on humans — suggesting a common evolutionary origin for countless vastly different skin appendages.

A new study, scheduled for online publication Tuesday in the journal eLife, examines the process as it occurs in a common laboratory genetics model, the zebrafish.

“We’ve found that the molecular pathways that underlie development of scales, hairs and feathers are strikingly similar”, said the study’s lead author, Andrew Aman, a postdoctoral researcher in biology at the University of Virginia.

Aman and his co-authors, including UVA undergraduate researcher Alexis Fulbright, now a Ph.D. candidate at the University of Utah, used molecular tools to manipulate and visualize scale development in zebrafish and tease out the details of how it works. It turns out, as the researchers suspected, skin appendages seen today originated hundreds of millions of years ago in primitive vertebrate ancestors, prior to the origin of limbs, jaws, teeth or even the internal skeleton.

While zebrafish have been studied for decades in wide-ranging genetic experiments, their scale development has mostly been overlooked, according to Aman.

“Zebrafish skin, including the bony scales, is largely transparent and researchers probably have simply looked past the scales to the internal structures”, he said. “This is an area ripe for investigation, so we got the idea to look at the molecular machinery that drives the development of patterning in surface plating. We discovered profound similarities in the development of all skin appendages, whether scales, hair, fur or feathers.”

Aman works in the lab of David Parichy, the study’s senior author and the Pratt-Ivy Foundation Distinguished Professor of Morphogenesis in UVA’s Department of Biology. Parichy’s lab investigates developmental genetics of adult morphology, stem cell biology and evolution, using zebrafish and related species as models. A high percentage of the genes in these common aquarium fish are the same as in humans — reflecting a common ancestry going back to the earliest common vertebrates that populated the ancient seas.

Developmental patterning — such as how scales take shape and form in slightly overlapping layers (in the case of zebrafish, there are more than 200 round scales on each side of the fish) — is a critical part of all development, including how stem cells differentiate and become, for example, bone cells, skin cells and any of the hundreds of kinds of cells that comprise the 37 trillion or so cells in the human body.

How cells differentiate and organize into precise shapes (and sometimes develop into misshapen forms that can result in congenital diseases, cancers and other abnormalities) is of utmost interest to developmental biologists like Parichy and Aman. Understanding the process provides insights into birth defects, cancer and genetic disease, and how the process might be fixed when gone awry.

As an example, teeth, which are actually an epidermal appendage, sometimes are subject to developmental problems. “Defects we find in fish scale development are reminiscent of the developmental problems that can occur with teeth,” Parichy said. “Since scales regenerate, maybe there is a way to get teeth to regenerate.”

“This research helps us make important links between the natural history of life on Earth, the evolutionary process and human disease”, Aman said.

Flashlight fish, new research


This video says about itself:

The Flashlight Fish Anomalops katoptron Uses Bioluminescent Light to Detect Prey in the Dark

9 February 2017

To hunt in the dark, these fish bring their own ‘flashlights’.

Scientists just discovered a weird new fish and we can’t tell if it’s cool or terrifying or both.

From the Ruhr-University Bochum in Germany:

Light receptors determine the behavior of flashlight fish

July 12, 2018

Biologists at the Ruhr-Universität Bochum characterized new, unknown photoreceptors from the bioluminescent flashlight fish Anomalops katoptron. The photoreceptors known as opsins allow the fish to detect light with a specific wavelength. As published on the 11th July 2018 in PLOS ONE the scientists found new opsin variants, which are specialized to detect low intensity blue light in the wavelength range of bioluminescent light emitted by the fish. The blue light can be used to influence the fish behaviour.

The authors conclude that this specific blue light receptors and light processing is an evolutionary adaptation to the ecological environment of the fish. The study is an interdisciplinary biological approach combining the expertise of geneticist Dr Minou Nowrousian and Prof Dr Ulrich Kück, molecular biologist Dr Melanie Mark, zoologists Dr Jens Hellinger and Dr Marcel Donner as well as physiologist and optogeneticist Prof Dr Stefan Herlitze.

Two opsin variants to detect blue light

Besides the fact that bioluminescence is a widespread phenomenon in marine environments it is currently not known how bioluminescence is processed and which physiological and behavioural consequences bioluminescence is evoking in most species. The flashlight fish Anomalops katoptron can be seen in shallow waters of coral reefs at moonless nights and is found during the day in caves up to 400 metres deep. Light organs are situated under the eye, which produce blue light with a wavelength of 490 nanometres, which is used to detect and hunt prey.

The research team analysed the photoreceptor composition of the retina and found two visual pigments, which resemble the visual pigments expressed in the mammalian retina. Both of these photoreceptors are activated by low intensity blue light in the range of 490 nanometres, which match the wavelength range of its own bioluminescent light.

Fish are conditioned during feeding

Next, the research team analysed if Anomalops katoptron uses blue light for behavioural responses. They performed a Pavlovian conditioning task with eight fish, where the fish had to associate feeding with a specific light pulse. “The fish were fed in darkness, but we used a strong red flashlight to illuminate the feeding area. We thought originally that the fish cannot see the red light”, says Jens Hellinger, “but found that they can associate the red light with food. Thus, once we switched on the red light at the corner of the aquarium, the fish swam into the light beam.”

The scientists used this phenomenon to perform a behavioural test, to show that flashlight fish would react only to specific wavelength of light. They used a much lower light intensity in comparison to the red flashlight and found that the fish now only reacted to low intensity blue but not red light.

Adaptation to star light and bioluminescence

“The visual system of flashlight fish seems to be adapted to detect low intensity light, such as star light or bioluminescent light to adjust their own behaviour”, concluded Stefan Herlitze. The low light detection reveals a new behavioural function of bioluminescence in fish.

Bioluminescence

Bioluminescence involves a chemical process where free energy is converted into light. The phenomenon is found in various different species from bacteria, fungi and insects to vertebrates. Bioluminescent light is often produced in specialized cell organelles or light organs. Light organs filled with symbiotic bacteria are for example often found in deep-sea fish to produce behaviour-relevant light signals.

African electric fish, new research


This video shows Gnathonemus petersii fish.

From ScienceDaily:

A fish that subtracts its own electric signals to better ‘see’ through its murky habitat

July 11, 2018

The elephant-nose fish Gnathonemus petersii relies on electricity to find food and navigate through the obstacles riddling its native murky African rivers. On July 11 in the journal Neuron, Columbia University researchers present evidence that the fish’s ability to accurately “see” an “electrical image” of its surroundings requires it to filter out its own electrical interference.

“We needed to determine whether being able to predict its own electrical signals would help the fish better detect environmental cues”, says Nathaniel Sawtell, a neuroscientist at Columbia’s Zuckerman Mind Brain Behavior Institute. “So using both neural recordings and behavioral experiments, we showed that these predictions known as negative images actually do help the fish sense external signals related to hunting prey.”

As an electric fish, the elephant-nose fish has two specialized systems that help it sense its surroundings — a passive system attuned to the minute electric signatures of everything living in its environment, including prey, and an active system that voluntarily emits brief pulses of electricity. The fish uses these electrical pulses to both communicate with other electric fish and sense its environment by painting an “electric image” of it to aid in navigation.

“The fish’s own electrical pulses cause large neural responses that interfere with the passive system,” says Sawtell. “Our work shows how changes in neural connections produce negative images to cancel out this interference.”

While earlier studies speculated that the elephant-nose fish might generate these negative images, no evidence had existed to directly demonstrate their functional importance. But the authors showed that delivering a drug that interfered with the formation of negative images essentially blinded the fish to external electrical signals.

“An important part of this work has been the integration of experimental and theoretical approaches to understanding neural circuits”, says Sawtell. “From here, we’re trying to take the lessons we’ve learned from the electric fish and apply them to related systems, including the mammalian cerebellum and auditory system.”

Endemic Baltic Sea fish species discovered


This September 2017 video says about itself:

Flatfish With Parasites – Flounder Cleaning Station

Snorkeling in icy cold water in Gotland, Sweden, May 2017. I found one frozen flounder and removed some leech-like parasites from its skin. Crazy clear visibility like never before in the Baltic Sea.

From the University of Helsinki in Finland:

The first endemic Baltic Sea fish species received its name

July 11, 2018

The “Baltic flounder” Platichthys solemdali is the first fish species shown to be native only to the Baltic Sea, i.e. the first endemic fish described from the area and one of the only two known endemic species when considering any organism. The fact that a new vertebrate species is found and described from European waters, and especially from the species-poor Baltic Sea still after more than a century of biological research in the area, makes this finding significant.

“The reason why this species has not been recognized before is that it appears to be near to identical to the other flounder species, the European flounder, Platichthys flesus, also occurring in the Baltic Sea”, says professor Juha Merila, one of the authors behind the article, from the Faculty of Biological and Environmental Sciences.

Currently the two species can be distinguished only with genetic methods, or by studying their eggs and sperm. The species also differ in their interaction with the environment: the newly described Baltic flounder lays sinking eggs on the sea floor in coastal areas while the European flounder spawns buoyant eggs in deep areas out in the open sea. The new species is more abundant in the Gulf of Finland while the distribution of the European flounder is centered to the central and southern Baltic Sea.

Previous research by the same research group uncovered the ecological speciation process that drove the evolution of these flounders, which is rarely witnessed in the marine environment and had occurred at record speed in evolutionary time scales. However, the two flounders can officially be considered separate species only now after the new species has been formally described.

“Because the definition of a species and the binomial scientific name in connection to that are central concepts and entities of biology in general and in biological taxonomy in particular, the formal description and naming of a species still constitute an important part in the understanding of biological order,” states Merilä.

The official separation of the flounders into two distinct species through a formal description and naming procedure is essential for conducting more accurate stock assessments and highly relevant to the management and conservation of the species that in many areas constitute mixed stocks.

The commercial fishing of flounders in the Baltic Sea has been partially based on the wrong assumption that stocks consist of a single species, while the two flounder species may co-occur in several locations. As fisheries might currently be targeting both flounders species, this poses the danger of unknowingly over-exploiting the species that constitute the weaker component of a mixed-stock.

Great Barrief Reef fish and snakes


This video says about itself:

Deadly Predators of the Reef: the Queensland Grouper and the Sea Snake | BBC Earth

30 June 2018

The reef is full of dangerous predators, including the giant Queensland grouper and the deadly sea snake.

Stretching a full 2000 kilometres in length and made up of 3000 individual reef systems and hundreds of islands, Australia’s Great Barrier Reef is breathtakingly beautiful. Given world heritage status in 1981 it is one of the wonders of the natural world.