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First In Fish: ‘Fully Warm-Blooded’ Moonfish Prowls The Deep Seas

NOAA Fisheries biologist Nick Wegner holds an opah caught during a research survey off the California coast. Researchers say the opah is the first fish known to be fully warm-blooded, circulating heated blood throughout its body.

NOAA Fisheries biologist Nick Wegner holds an opah caught during a research survey off the California coast. Researchers say the opah is the first fish known to be fully warm-blooded, circulating heated blood throughout its body.

Over decades of studying the oceans’ fishes, some species have been found to have partial warm-bloodedness. But scientists say the opah, or moonfish, circulates heated blood — and puts it to a competitive advantage.

“Nature has a way of surprising us with clever strategies where you least expect them,” according to NOAA Fisheries biologist Nicholas Wegner, who works in the Southwest Fisheries Science Center in La Jolla, Calif. In a news release about finding, Wegner said, “It’s hard to stay warm when you’re surrounded by cold water but the opah has figured it out.”

The opah is not a small animal; it’s roughly the size of a car tire and often weighs more than 100 pounds. In the past, it was often viewed as a fairly complacent dweller of water that’s hundreds of feet deep.

Now researchers say the opah also uses internal warmth to help it move quickly and efficiently — and kill prey such as squids and smaller fish. As the researchers describe in the journal Science, the fish relies on an internal heating system that seems to have been developed in frigid waters.

From the National Oceanic and Atmospheric Administration Fisheries:

“Satellite tracking showed opah spend most of their time at depths of 150 to 1,300 feet, without regularly surfacing. Their higher body temperature should increase their muscle output and capacity, boost their eye and brain function and help them resist the effects of cold on the heart and other organs, Wegner said.

“Fatty tissue surrounds the gills, heart and muscle tissue where the opah generates much of its internal heat, insulating them from the frigid water.”

Heat is generated from the opah’s large wing-like pectoral fins, which were previously thought only to help it swim fast enough to catch prey.

The agency’s researchers say they found an unexpected design tweak in the opah’s gills that sets it apart from other fish: a counter-current heat exchange in which blood vessels carrying warm blood are twined around vessels that are bringing oxygen — and cold temperatures — from the gills. The design helps the opah maintain endothermy (warm-bloodedness).

“The fish had an average muscle temperature about 5 degrees C (roughly 9 degrees Fahrenheit) above the surrounding water while swimming about 150 to 1,000 feet below the surface,” NOAA says.

Revelations about the opah’s blood temperature come after a moonfish was captured in a striking photograph off the California coast earlier this year, an encounter that was seen as part of a surge in opah sightings off the western U.S. coast.

Opah have more commonly been spotted in Hawaii — including at fish auctions.

Of the flavor, National Geographic has reported:

“Opah are unusual in that different parts of their body look and taste different, the biologist explains. The upper part of the fish looks like tuna and tastes like a cross between tuna and salmon, he says. But their pectoral muscles — the ones that power the fins on the side of the body — look and taste a bit like beef.”

Originally published here: http://www.npr.org/sections/thetwo-way/2015/05/15/407072979/first-in-fish-fully-warm-blooded-moonfish-prowls-the-deep-seas

Author: Bill Chappell

Posted May 18th, 2015.

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Cichlid Fish Display Extensive Social Interactions

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Neolamprologus pulcher (N. pulcher) is the breed of cichlid used in the study.

Credit: Dario Josi

A new study shows that cichlid fish reared in larger social groups from birth display a greater and more extensive range of social interactions, which continues into the later life of the fish. Researchers say this indicates the fish develop more attuned social behavior as a result of early environments.

The researchers also found that those fish raised in a more complex social environment have a different brain structure to those who experienced fewer group members in early life. If fish experienced the complex social environment for 2 month they had a larger hypothalamus: the area that contains most of the brain nodes of the ‘social behavior network’. They also had a larger ‘optic tectum’, which processes visual stimuli and could be related to the need to process more visual stimuli in larger groups, say researchers.

The brains of fish with enhanced social skills were not bigger overall than those reared in small groups; however, the ‘architecture’ within the brain was different.

“Our data suggests that, during development, relative brain parts change their size in response to environmental cues without affecting overall brain size: increasing certain parts forces others to decrease concurrently. These ‘plastic’ adjustments of brain architecture were still present long after the early stages of social interaction,” said study author Dr. Stefan Fischer, from Cambridge University’s Department of Zoology.

“Social animals need to develop social skills, which regulate social interactions, aggression and hierarchy formations within groups. Such skills are difficult and costly to develop, and only beneficial if the early social environment predicts a high number of social interactions continues to be critically important later in life,” he said.

For the study, published this week in the journal The American Naturalist, researchers used the Neolamprologus pulcher (N. Pulcher) breed of cichlid, primarily found in Lake Tanganyika — the great African freshwater lake that feeds into the Congo River.

N. Pulcher lives in family groups with up to 25 individuals, with one breeder pair and several helpers participating in territory defense and raising of offspring — known as ‘cooperative breeding’. To test for social skills, the researchers reared juvenile fish over two months with either three or nine adult group members, and observed all social behaviors at key experimental points.

These interactions included ‘lateral display’ — when one fish interrupts another by displaying their body side-on, sometimes as a mating ritual — as well as ramming, tail quivering, and ‘mouth fighting': a social display in which fish lock mouths to challenge each other over everything from food to mates.

Six month after this test phase, individual fish brains were measured to investigate the long term consequences of early group size on brain morphology, revealing differences in brain architecture.

The researchers say that one of the effects on social behavior in larger groups might be the perception of environmental risk. “In the wild, larger social groups of N. Pulcher represent a low-risk environment with enhanced juvenile survival. Being part of a larger, safer group may increase the motivation of juveniles to interact socially with siblings, enhancing the opportunities to acquire social skills,” said Fischer.

As perhaps with any social creature, Fischer points out that higher social competence and the ability to conform to social hierarchies may well stand the cichlids in good stead in later life:

“Group size for these fish stays relatively stable across the years, they have delayed dispersal. Remaining in a larger group means a better chance of survival. Fish reared in large groups showed more submissive and less aggressive behavior to big fish in the group, social behavior which greatly enhances the survival chances of smaller fish.”

Fischer added: “In highly social animals, such as cooperative breeders, almost all activities involve social interactions, where individuals need to adequately respond to social partners. In larger groups, these interactions are more common and individuals developing sophisticated social skills during childhood might highly benefit from them later in life.”

Source: University of Cambridge

Originally published here: www.sciencedaily.com/releases/2015/05/150507114048.htm

Posted May 15th, 2015.

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Some Like it Cold: Sea Anemones found in Antarctica

The Edwardsiela andrillae sea anemone measures less than 1 inch in length. (Credit: Courtesy Frank Rack, ANDRILL Science Management Office, University of Nebraska-Lincoln)

Using a camera-equipped robot to explore beneath the Ross Ice Shelf off Antarctica, scientists and engineers with the Antarctic Geological Drilling (ANDRILL) Program made an astonishing discovery.

Thousands upon thousands of small sea anemones were burrowed into the underside of the ice shelf, their tentacles protruding into frigid water like flowers on a ceiling.

“The pictures blew my mind,” said Marymegan Daly of Ohio State University, who studied the specimens retrieved by ANDRILL team members in Antarctica.

The new species, discovered in late December 2010, was publicly identified for the first time in a recent article in the journal PLoS ONE.

Though other sea anemones have been found in Antarctica, the newly discovered species is the first known to live in ice. They also live upside down, hanging from the ice, compared to other sea anemones that live on or in the sea floor.

The white anemones have been named Edwardsiella andrillae, in honor of the ANDRILL program. The discovery was “total serendipity,” said Frank Rack, executive director of the ANDRILL Science Management Office at the University of Nebraska-Lincoln and associate professor of Earth and atmospheric sciences at UNL.

“When we looked up at the bottom of the ice shelf, there they were,” he said.

Scientists had lowered the robot, a 4 1/2-foot cylinder equipped with two cameras, a side-mounted lateral camera and a forward-looking camera with a fish-eye lens, into a hole bored through the 270-meter-thick shelf of ice that extends more than 600 miles northward into the Ross Sea from the grounding zone of the West Antarctic Ice Sheet.

Their mission, financed by the National Science Foundation in the U.S. and the New Zealand Foundation for Research, was to learn more about the ocean currents beneath the ice shelf and provide environmental data for modeling the behavior of the ANDRILL drill string, Rack said. They didn’t expect to discover any organisms living in the ice, and surely not an entirely new species.

The discovery indicates that, even after 50 years of active U.S. research, more remains to be studied about the southernmost continent, said Scott Borg, head of the Antarctic Sciences Section in the NSF’s Division of Polar Programs.

“Just how the sea anemones create and maintain burrows in the bottom of the ice shelf, while that surface is actively melting, remains an intriguing mystery,” he said. “This goes to show how much more we have to learn about the Antarctic and how life there has adapted.”

Rack, who is U.S. principal investigator for the environmental surveys that were conducted as part of the international ANDRILL Coulman High project, had left the site just prior to the discovery. He was listening by radio when he heard the report from the robot deployment team — engineers Bob Zook, Paul Mahecek and Dustin Carroll — who began shouting as they saw the anemones, which appeared to glow in the camera’s light.

“They had found a whole new ecosystem that no one had ever seen before,” Rack said. “What started out as a engineering test of the remotely operated vehicle during its first deployment through a thick ice shelf turned into a significant and exciting biological discovery.”

In addition to the anemones, the scientists saw fish that routinely swam upside down, the ice shelf serving as the floor of their undersea world. They also saw polychaete worms, amphipods and a creature they dubbed “the eggroll,” a 4-inch-long, 1-inch-diameter, neutrally buoyant cylinder that seemed to swim using appendages at both ends of its body. It was observed bumping along the field of sea anemones under the ice and hanging on to them at times.

The anemones measured less than an inch long in their contracted state — though they get three to four times longer in their relaxed state, Daly said. Each features 20 to 24 tentacles, an inner ring of eight longer tentacles and an outer ring of 12 to 16 tentacles. After using hot water to stun the creatures, the team used an improvised suction device to retrieve them from their burrows. They were then transported to McMurdo Station for preservation and further study.

Because the team wasn’t hunting for biological specimens, they were not equipped with the proper supplies to preserve them for DNA/RNA analyses, Rack said. The anemones were placed in ethanol at the drilling site and some were later preserved in formalin at McMurdo Station.

Many mysteries remain. Though some sea anemones burrow into sand with tentacles or by expanding and deflating the base of their bodies, those strategies don’t seem feasible for ice. It is also unclear how they survive without freezing and how they reproduce. There is no evidence of what they eat, although they likely feed on plankton in the water flowing beneath the ice shelf, Daly said.

Rack said a proposal is being prepared for further study of this unusual environment using a robot to explore deeper in the ocean and further from the access hole through the ice. NASA is helping finance the development of the new underwater robot because the Antarctic discoveries have implications for the possibility of life that may exist on Europa, the ice-covered moon of Jupiter.

He said researchers hope to return to Antarctica as early as 2015 to continue studying the sea anemones and other organisms beneath the ice shelf.

 

Originally published here: http://newsroom.unl.edu/releases/2014/01/16/ANDRILL+team+discovers+ice-loving+sea+anemones+in+Antarctic

Posted January 23rd, 2014.

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Solving the Mysteries of the Sea: Biologists in Norway Strive to Discover Full Extent of Biodiversity

A crawfish that lives on the seabed along the Norwegian coast, Campylaspis costata is one of the 76 known species of crawfish found in Norwegian waters that we now know more about as a result of inventories conducted for the Norwegian Taxonomy Initiative. (Credit: Photo: Henrik Glenner, University of Bergen)

More than a thousand new species -nearly one-quarter of which are new to science — have been discovered in Norway since a unique effort to find and name all of the country’s species began in 2009.

The Norwegian Taxonomy Initiative is one of just two government efforts worldwide where scientists are being funded to find and catalogue the country’s true species diversity.

The Norwegian initiative is focused on describing poorly known species groups across the country’s varied habitats, from its alpine plateaus to the northernmost reaches of the island archipelago of Spitsbergen.

The finds range from new species of insects and lichens to new species of molluscs and cold-water sponges. The information gives scientists and policymakers a better platform for understanding of the complexity and function of Norway’s ecosystems.

“These are very good results that provide new knowledge of both individualspecies and ecosystems,” says Ivar Myklebust, director of the Norwegian Biodiversity Information Centre, which is coordinating the taxonomy initiative on commission from the Norwegian Ministry of the Environment.

Scientists believe that there are roughly 55,000 species in Norway, but until now only 41,000 have been discovered. The 1165 new species discovered by the taxonomy initiative over the last four years are thus an important addition to this number. However, it will take time before the species that are thought to be new to science can be added to this list. These newly discovered species must first be given a scientific name and a description of the species must be published in a scientific publication.

“Norway’s land, seas and coastal areas have a unique variety of landscapes and ecosystems with great variation over short distances, which is rare in a global context,” said Tine Sundtoft, Norway’s Minister of Climate and the Environment. “This gives us a rich and varied flora and fauna. The Government will take our management responsibilities seriously.”

Many new insect species The biggest discoveries have been made in the major species-rich groups where previous knowledge has been poor — including in the groups that include wasps, flies and mosquitoes.

Scientists believe that there are thousands of species in Norway yet to be discovered in these groups. The figures from the taxonomy initiative shows that nearly 60 per cent of the new species are insects or other small terrestrial invertebrates (729 species), including 667 new species of insects, 17 new spider species and 18 new springtail species.

A boost in knowledge about fungi Fungi represent another large and species-rich group in Norway. Since 2009, scientists have found 227 new fungi species as part of the taxonomy initiative.

Some of these fungal species have been discovered using DNA analysis to clarify the relationship between species. This has led scientists to split some species into two, or to increase the species numbers from 14 to 31, as was the case for coral fungi.

New marine species Norway’s rich marine environment supplied 157 new species, including sponges, snails, slime worms, bristle worms, fish parasites, molluscs and starfish. Another 16 new species were discovered in brackish and fresh water, primarily fish parasites and small crustaceans.

Marine species are not as accessible as terrestrial species for researchers. As a result, 48 per cent of the species found as part of the taxonomy initiative are completely new to the scientific world and have never before been described scientifically.

In comparison, 18 per cent of the new terrestrial species are what scientists call undescribed species. In some of the very poorly known marine species groups such as the worm-like (aplacophoran) molluscs that live on the ocean floor, Aplacophora/shell less molluscs, the proportion of undescribed species may be as high as 90 per cent.

New knowledge about better-known species groups Norway’s landscape varies greatly in its topography, climate and habitats, which are home to a rich lichen and moss flora, with more than 2000 species of lichens and about 11 000 species of mosses.

“Even though we believe that the flora of both lichens and mosses are relatively well known, we have learned a great deal about the incidence and prevalence of both groups as a result of the initiative” says Ingrid Salvesen, senior adviser at the Norwegian Biodiversity Information Centre and coordinator of the Norwegian Taxonomy Initiative.

This is partly because much of the current knowledge and species descriptions are based on very old data. DNA analyses, combined with surveys in little explored areas, have proven to be very useful.

Salvesen also says that the initiative has given scientists a better understanding of where better-known species are found and the relationships of these species to different habitats. This is an important cornerstone for knowledge-based management.

“Geo-referenced information records of species give us new knowledge of the habitat that these species live in, and the organisms that they live with,” Salvesen says. “That gives us the ability to better understand the complex interactions of nature.”

DNA reveals new species DNA barcoding is a method for identifying species using differences in genetic material. The method involves comparing a short DNA sequence of an unknown organism to known sequences in a reference library.

The DNA barcodes can identify species from just tiny tissue samples, such as from an insect leg or a drop of blood.

A selection of the material collected by the Taxonomy Initiative has been made available for DNA barcoding in collaboration with the Norwegian Barcode of Life network (NorBOL).

To date, NorBOL has registered barcodes from approximately 3800 species in Norway, over half of which have come via the Taxonomy Initiative. NorBOL is part of a global effort to build up the reference library of DNA barcodes for more and more of the Earth’s species.

The Research Council of Norway has provided funding for the country’s national infrastructure for DNA barcoding up to and including 2018, which will allow for a great number of Norwegian species to be registered in the library.

Facilitator and catalyst The major activity that has been generated by the Norwegian Taxonomy Initiative has revitalized the country’s biosystematics research. A large number of academics, experts, technicians and students from most natural science research institutions in Norway are involved in the survey work.

The project has also led to the establishment of solid, professional networks across national boundaries. Norwegian researchers have established working relationships with their colleagues in Sweden, Denmark, Finland, Estonia, the UK, Ireland, the Netherlands, Belgium, Poland, Germany, Austria, Hungary, Georgia Spain, Canada and Japan.

42 projects in five years The Norwegian Taxonomy Initiative has started 42 inventory projects for mapping and identifying species in Norway since its inception in 2009. About half of these projects are completed or will be completed during 2013. Another eight new projects will be initiated in 2014.

 

Originally published here: http://www.alphagalileo.org/ViewItem.aspx?ItemId=137581&CultureCode=en

Posted January 8th, 2014.

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Life in the Splash Zone

A male Pacific leaping blenny on the island of Guam. Photo: Courtney Morgans/UNSW.

One of the world’s strangest animals – a legless, leaping fish that lives on land – uses camouflage to avoid attacks by predators such as birds, lizards and crabs, new research shows.

UNSW researchers, Dr Terry Ord and Courtney Morgans, of the Evolution and Ecology Research Centre, studied the unique fish – Pacific leaping blennies – in their natural habitat on the tropical island of Guam.

Their study will be published in the journal Animal Behaviour.

“This terrestrial fish spends all of its adult life living on the rocks in the splash zone, hopping around defending its territory, feeding and courting mates. They offer a unique opportunity to discover in a living animal how the transition from water to the land has taken place,” says Dr Ord, of the UNSW School of Biological, Earth and Environmental Sciences.

The researchers first measured the colour of five different populations of the fish around the island and compared this with the colour of the rocks they lived on. “They were virtually identical in each case. The fish’s body colour is camouflaged to match the rocks, presumably so they aren’t obvious to predators,” says Dr Ord.

To see if background matching reduced predation, the researchers created realistic-looking models of blennies out of plasticine. “We put lots of these model blennies on the rocks where the fish live, as well as on an adjacent beach where their body colour against the sand made them much more conspicuous to predators,” says Dr Ord.

“After several days we collected the models and recorded how often birds, lizards and crabs had attacked them from the marks in the plasticine. We found the models on the sand were attacked far more frequently than those on the rocks.

“This means the fish are uniquely camouflaged to their rocky environments and this helps them avoid being eaten by land predators.”

The researchers then studied the body colour of closely related species of fish, some of which lived in the water and some of which were amphibious, sharing their time between land and sea.

“These species provide an evolutionary snapshot of each stage of the land invasion by fish,” says Dr Ord.

The similarities in colour between these species and the land-dwelling fish suggest the ancestors of the land-dwelling fish already had a colouration that matched the rocky shoreline before they moved out of the water, which would have made it easier for them to survive in their new habitat.

The Pacific leaping blenny, Alticus arnoldorum, is about four to eight centimetres long and leaps using a tail-twisting behaviour. It remains on land all its adult life but has to stay moist to be able to breathe through its gills and skin.

Originally published here: http://newsroom.unsw.edu.au/news/science/secrets-legless-leaping-land-fish

Posted December 3rd, 2013.

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