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Snails Consume Fish

The deadly cone snail is never added to an aquarium by choice, and it should never be handled. It has a powerful venom that, in larger specimens, can even kill a human. In fact, the harpoon that delivers the venom is so powerful that, in some cases, it can penetrate a wetsuit.

Although they very, very rarely make their way into the aquarium hobby, some cone snails have been found in tanks after hitchiking on live rock. If you find one, you should attempt to remove it as soon as possible without touching it, for example, by using a baited trap.

If you wind up with one of the largest species of cone snails in your tank, here’s what can happen. This is a video from the BBC taken on the Great Barrier Reef of a cone snail attacking a fish.

Source: http://www.bbc.co.uk/nature/life/Conus

Posted May 29th, 2015.

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Best Plants for Beginners

By Lea Maddocks

As Lea Maddocks explains in the second part of her article in the December 2012 issue,  Setting Up a Successful Low-Tech Planted Tank Like a Pro, Part 2: Aquascaping and Maintaining Your Planted Tank, choosing aquatic plants that fit your skill level and fit the look that you want can be challenging. However, some plants have a reliable track record of doing well in low-tech setups.

Let’s start with the best epiphytic plants. These should not be planted in the substrate, instead they can be tied to rocks or stones and allowed to grow with their roots exposed.

Java fern and Java moss are both very hardy plants. Photograph by Gary Lange.

Java fern varieties (Microsprum pteropus) including regular, crested (aka ‘windelov’), and narrow leaf

Anubias species

Congo fern – Bolbitus heudelotii

Mosses, including Java moss

Next come floating plants. Similar to epiphytic plants, these should not be buried in the substrate. Instead they should be left floating freely in the aquarium. They are great for providing shade to skittish fish.

Duckweed is an easily grown floating plant, but be warned that it can easily reach plague proportions. Photograph by Albert Connelly, Jr.

Hornwort (Ceratophyllum demersum)

Lacefern/watersprite (Ceratopteris thalictroides)

Duckweed (Lemna minor)

Mosquito fern (Azolla caroliniana)

Brazillian pennywort (Hydrocotyle leucocephala)

Water lettuce

Some stem plants are appropriate for beginners. These must be planted in the substrate.

Green hygro (Hygrophila polysperma) is a relatively easy-to-grow stem plant. Photograph by MP. & C. Piednoir.

Some ludwigia, including the red Ludwigia repens

Elodea/Egeria – Egeria densa

Green hygro (Hygrophila polysperma)

Water wisteria (Hygrophila difformis)

Lacefern/watersprite (Ceratopteris thalictroides, note this can be planted as a stem plant or left floating)

Brazillian penny wort (Hydrocotyle leucocephala)

Bacopa – Bacopa australis, B. monnieri, Bacopa caroliniana

Camboba

Myriophyllum mattogrossense

Amazon swords, the ozelot variety has red flecks and can be great for color

Rotala rotundifolia

Cryptocoryne species, especially browns like C. Wendtii, C. Lutens

Pearlweed (Hemiantus glomeraturs), which was formerly confused with H. micranthemoides

Saggitaria and dwarf sgaggitarita

Pygmy chain sword (Helanthium tenellus)

Posted May 14th, 2015.

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Book Excerpt: Reef Aquarium Fishes

Organized by family for easy reference, each profile in Reef Aquarium Fishes includes all essential care, feeding and husbandry advice. The species profiled include all available reef aquarium choices, with scores of seldom seen, rare and recently discovered species. Written by the worlds most-read, most respected expert on marine fishes for the home aquarium, The PocketExpert Guide to Reef Aquarium Fishes is a must-read for any fish enthusiasts.

About the Author

Scott W. Michael is an internationally recognized writer, underwater photographer, and marine biology researcher specializing in reef fishes. He is the author of the Pocket Expert Guide to Marine Fishes (Microcosm/TFH), the Reef Fishes  series (Microcosm/TFH), and Reef Sharks and Rays of the World (Microcosm/TFH).

Having studied biology and the University of Nebraska, he has been involved in research projects on sharks, rays, frogfishes, and the behavior of reef fishes. He has also served as a scientific consultant for National Geographic Explorer and the Discovery Channel. His work has led him from Cocos Island in the Eastern Pacific to various points in the Indo-Pacific as well as the Red Sea, the Gulf of Mexico, and many Caribbean reefs.

A marine aquarist since boyhood, he has kept tropical fishes for more than 30 years, with many years of involvement in the aquarium world, including a period of retail store ownership. He is a partner in an extensive educational website on the coral reef environment, www.coralrealm.com.

Scott lives with his wife, underwater photographer Janine Cairns-Michael, and their Golden Retriever, Ruby, in Lincoln, Nebraska.

Excerpt from Hogfishes (Genus Bodianus)

The hogfishes are some of the hardiest members of the wrasse family. As a whole, they are durable aquarium fish that readily accept most aquarium fare, while ignoring all live corals. Most can be kept in reef aquariums as juveniles, but as they grow they will eat worms, snails, small clams, and crustaceans. The size of the aquarium needed to harbor a hogfish will depend on the species—most small to medium-sized members of the family (i.e., those species that attain a maximum length of less than 10 in. [25 cm]) can be kept in tanks ranging from 20 to 75 gallons (76 to 285 L), while more robust species require a tank of 135 gallons (513 L) or larger once they reach adult size. They need hiding places as well as ample swimming room.

Hogfishes, unlike certain other wrasses, do not bury in the substrate, so the depth of sand in your tank is of little concern. However, several of these fishes will hunt buried prey items by blowing jets of water at the finer substrate. This predatory behavior is fascinating to watch and will also stir the upper layers of the substrate.

Spanish Hogfish (Bodianus rufus): a graphic warning about hogfish feeding habits—motile invertebrates, such as brittle stars, are likely to meet this fate. Photograph by Scott W. Michael.

Many hogfishes will not tolerate the presence of members of their own species in the same tank, but they can be kept with other members of their genus. One caution: avoid placing two similarly colored species in the same tank.
As far as unrelated species are concerned, hogfishes can be belligerent toward smaller fishes, more docile species, or those fishes introduced after the hogfish has become an established resident of the tank. The moderate- to large-sized hogfishes should be kept with fish species that can hold their own, like lionfishes, squirrelfishes, soldierfishes, smaller groupers, goatfishes, angelfishes, hawkfishes, medium-sized damselfishes, sand perches, and less aggressive triggerfishes. Adding a hogfish to an established community of aggressive fishes, however, can cause the hogfish to remain hidden most of the time and never acclimate. Of course, large frogfishes, scorpionfishes, and groupers will eat any hogfish that they can swallow whole. While the larger hogfish species simply won’t fit into the average reef tank community, some of the smaller members of this group are worthy of consideration. Choose carefully, based on size and feeding habits.

Bodianus mesothorax. Photograph by Scott W. Michael.

Bodianus mesothorax
Mesothorax Hogfish
Maximum Length: 7.5 in. (19 cm).
Aquarium Suitability: This species is generally durable and hardy, with most individuals acclimating to the home aquarium.
Reef Compatibility: Safe with stony corals. Safe with soft corals. Threat to ornamental crustaceans. Threat to other invertebrates.

Bodianus mesothorax juvenile. Photograph by Scott W. Michael.

Bodianus diana. Photograph by Scott W. Michael.

Bodianus diana
Diana’s Hogfish
Maximum Length: 9.8 in. (25 cm).
Aquarium Suitability: This species is generally durable and hardy, with most individuals acclimating to the home aquarium.
Reef Compatibility: Safe with stony corals. Safe with soft corals. Threat to ornamental crustaceans. Threat to other invertebrates.

Bodianus perditio. Photograph by Scott W. Michael.

Bodianus perditio
Goldspot Hogfish
Maximum Length: 31.5 in. (80 cm).
Aquarium Suitability: This species is generally durable and hardy, with most individuals acclimating to the home aquarium.
Reef Compatibility: Safe with stony corals. Safe with soft corals. Threat to ornamental crustaceans. Threat to other invertebrates.

Bodianus izuensis. Photograph by Scott W. Michael.

Bodianus izuensis
Izu Hogfish
Maximum Length: 4.3 in. (11 cm).
Aquarium Suitability: This species is generally durable and hardy, with most individuals acclimating to the home aquarium.
Reef Compatibility: Safe with stony corals. Safe with soft corals. Threat to ornamental crustaceans. Occasional threat to some other invertebrates.

Excerpted from the PocketExpert Guide to Reef Aquarium Fishes by Scott W. Michael. ©Microcosm/ TFH Publications. Used by permission.

Posted October 16th, 2014.

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Research Reveals Strange Marine Mammals of the Ancient North Pacific

The pre-Ice Age marine mammal community of the North Pacific formed a strangely eclectic scene, research by a Geology PhD student at New Zealand’s University of Otago reveals.

whales

A speculative life rendering of the fossil whale Balaenoptera bertae unearthed in the San Francisco Bay Area. The whale belongs within the same genus as minke and fin whales, indicating that the Balaenoptera lineage has lasted for 3-4 million years. Balaenoptera bertae would have been approximately 5-6 meters in length, slightly smaller than modern minke whales. It was named by University of Otago Ph.D. student Robert Boessenecker in honor of San Diego State University’s Professor Annalisa Berta.
Credit: Robert Boessenecker

Studying hundreds of fossil bones and teeth he excavated from the San Francisco Bay Area’s Purisima Formation, Robert Boessenecker has put together a record of 21 marine mammal species including dwarf baleen whales, odd double-tusked walruses, porpoises with severe underbites and a dolphin closely related to the now-extinct Chinese river dolphin.

Among his finds, which were fossilized 5 to 2.5 million years ago, is a new species of fossil whale, dubbed Balaenoptera bertae, a close relative of minke, fin, and blue whales.

Mr Boessenecker named the whale in honour of San Diego State University’s Professor Annalisa Berta, who has made numerous contributions to the study of fossil marine mammals and mentored many students.

Although an extinct species, it belongs within the same genus as minke and fin whales, indicating that the Balaenoptera lineage has lasted for 3-4 million years. Balaenoptera bertae would have been approximately 5-6 meters in length, slightly smaller than modern minke whales, Mr Boessenecker says.

His findings appear in the most recent edition of the international journal Geodiversitas.

The publication represents eight years of research by Mr Boessenecker, who was 18 in 2004 when he was tipped off by a local surfer about bones near Half Moon Bay. When he discovered the fossil site, he was astonished by the numerous bone-beds and hundreds of bones sticking out of the cliffs.

He excavated the incomplete skull of Balaenoptera bertae during early field research there in 2005 and it was encased in a hard concretion that took five years to remove.

“The mix of marine mammals I ended up uncovering was almost completely different to that found in the North Pacific today, and to anywhere else at that time,” he says.

Primitive porpoises and baleen whales were living side-by-side with comparatively modern marine mammals such as the Northern fur seal and right whales. And species far geographically and climatically removed from their modern relatives also featured, such as beluga-like whales and tusked walruses, which today live in the Arctic, he says.

“At the same time as this eclectic mix of ancient and modern-type marine mammals was living together, the marine mammal fauna in the North Atlantic and Southern Ocean were already in the forms we find today.”

Mr Boessenecker says this strange fauna existed up until as recently as one or two million years ago. Its weirdness was likely maintained by warm equatorial waters and barriers to migration by other marine mammals posed by the newly formed Isthmus of Panama, and the still-closed Bering Strait.

“Once the Bering Strait opened and the equatorial Pacific cooled during the Ice Age, modernised marine mammals were able to migrate from other ocean basins into the North Pacific, leading to the mix we see today,” he says.

 

Originally published here: http://www.eurekalert.org/pub_releases/2014-02/uoo-smm020414.php.

Posted March 15th, 2014.

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New Species of Marine Algae Discovered

algae3

The species that historically was quoted as the most abundant of coral algae that forms rodoliths at the Gulf of California in Mexico, is in reality a compound of five different species. This finding was made by Jazmín Hernández Kantun, marine biologist at the Autonomous University of South Baja California (UABCS), resulting in a change of paradigm in the study of the species known as Lithophyllum margaritae.

In fact, this Mexican research has reached Europe, where Hernández Kantun continues the project and her studies at Ireland’s National University with the support of the Mexican National Council of Science and Technology (Conacyt).

According with the Mexican researcher, the objective now is to determine the number of species of coral algae in Europe and Mexico trough molecular tests.

“Coral algae in Mexico and trough out the world are usually identified only by their shape and color. However, is necessary to investigate the species in depth, given that bigger biodiversity exists in this organism than previously thought” said the researcher.

About the importance of her discoveries, the researcher exposed that since 1992 the Habitats Directive of the European Union protects two rodoliths forming species: Lithothamnion corallioides and Phymatolithon calcareum; considering them the most abundant and important, giving them relevance as a marine ecosystem and using them as rich mineral fertilizers.

The specialist found that at least other two species: L. glaciale and L. tophiforme, should be considered in the protected group having the same characteristics.

The environmental value of coral algae lies in the fact that when detached during tides and accumulate in specific areas, they form mantles of rodoliths which are rich in calcium and used by corals, clams, larvae and mollusks as “foundation” to start their development.

However, global warming is changing the natural chemistry of ocean ecosystems, increasing the absorption of carbon dioxide and modifying its acidification levels (pH).

Hernández Kantun warned that the acidification could remove the mantles of rodoliths from the ecosystem, directly affecting the mollusks, corals and any other organism found in them.

The marine biologist insisted that the coral’s biological diversity must be considered. She assured that the negative effects of climate change and the level of repercussion that come with them are different for each species.

“A lot of research is missing in this field, we haven’t quite understood the diversity of this algae, is like saying that all dogs are alike when each breed has different genetics and response to environmental factors. Is not the same to protect one than five different species!” she highlighted.

After four years of studying for her PhD in Ireland and collaborating with researchers from the United Kingdom, Spain, France and Italy, Jazmín Hernández Kantun is waiting for her grade exam to return to Mexico where she plans to found a laboratory to continue with her research and use it for the conservation of this marine organisms.

Source: AlphaGalileo

Posted January 2nd, 2014.

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Art Imitating Life: A New Submarine May Be Based on Sting Rays

Richard Bottom, left, and Iman Borazjani hope their research on how stingrays swim will lead to the design of new underwater vehicles. (Photo: Douglas Levere)

BUFFALO, N.Y. ─ Stingrays swim through water with such ease that researchers from the University at Buffalo and Harvard University are studying how their movements could be used to design more agile and fuel-efficient unmanned underwater vehicles.

The vehicles could allow researchers to more efficiently study the mostly unexplored ocean depths, and they could also serve during clean up or rescue efforts.

“Most fish wag their tails to swim. A stingray’s swimming is much more unique, like a flag in the wind,” says Richard Bottom, a UB mechanical engineering graduate student participating in the research.

Bottom and Iman Borazjani, UB assistant professor of mechanical and aerospace engineering, set out to investigate the form-function relationship of the stingray — why it looks the way it does and what it gets from moving the way it does.

They will explain their findings at the 66th Annual Meeting of the American Physical Society Division of Fluid Dynamics. Their lecture, “Biofluids: Locomotion III – Flying,” is at 4:45 p.m. on Sunday, Nov. 24, in Pittsburgh, Pa.

The researchers used computational fluid dynamics, which employs algorithms to solve problems that involve fluid flows, to map the flow of water and the vortices around live stingrays.

The study is believed to be the first time the leading-edge vortex, the vortex at the front of an object in motion, has been studied in underwater locomotion, says Borazjani. The leading-edge vortex has been observed in the flight of birds and insects, and is one of the most important thrust enhancement mechanics in insect flight.

The vortices on the waves of the stingrays’ bodies cause favorable pressure fields — low pressure on the front and high pressure on the back — which push the ray forward. Because movement through air and water are similar, understanding vortices are critical.

“By looking at nature, we can learn from it and come up with new designs for cars, planes and submarines,” says Borazjani. “But we’re not just mimicking nature. We want to understand the underlying physics for future use in engineering or central designs.”

Studies have already proven that stingray motion closely resembles the most optimal swimming gait, says Bottom. Much of this is due to the stingray’s unique flat and round shape, which allows them to easily glide through water.

Borazjani and Bottom plan to continue their research and study the differences in movement among several types of rays.

Posted November 18th, 2013.

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“Just keep swimming, just keep swimming”… For Stability That Is

t0802_134

 

A quirk of nature has long baffled biologists: Why do animals push in directions that don’t point toward their goal, like the side-to-side sashaying of a running lizard or cockroach? An engineer building a robot would likely avoid these movements because they seem wasteful. So why do animals behave this way?

A multi-institutional research team, led by Johns Hopkins engineers, says it has solved this puzzle. In an article published in the Nov. 4-8 online edition ofProceedings of the National Academy of Sciences(PNAS), the team reported that these extra forces are not wasteful after all: they allow animals to increaseboth stability and maneuverability, a feat that is often described as impossible in engineering textbooks.

“One of the things they teach you in engineering is that you can’t have both stability and maneuverability at the same time,” said Noah Cowan, a Johns Hopkins associate professor of mechanical engineering, who supervised the research. “The Wright Brothers figured this out when they built their early airplanes. They made their planes a little unstable to get the maneuverability they needed.”

When an animal or vehicle is stable, it resists changes in direction. On the other hand, if it is maneuverable, it has the ability to quickly change course. Generally, engineers assume that a system can rely on one property or the other—but not both. Yet some animals seem to produce an exception to the rule. “Animals are a lot more clever with their mechanics than we often realize,” Cowan said. “By using just a little extra energy to control the opposing forces they create during those small shifts in direction, animals seem to increase both stability and maneuverability when they swim, run or fly.”

Cowan said this discovery could help engineers simplify and enhance the designs and control systems for small robots that fly, swim, or move on mechanical legs.

The solution to the animal movement mystery surfaced when the scientists used slow-motion video to study the fin movements of the tiny glass knifefish. These fish, each about three inches long, prefer to hide in tubes and other shelters, a behavior that helps them avoid being eaten by predators in the Amazon basin, the natural habitat of these shy fish. In a lab, the team filmed the fish at 100 frames per second to study how they used their fins to hover in these tubes, even when there was a steady flow of water in the fish tank.

“What is immediately obvious in the slow-motion videos is that the fish constantly move their fins to produce opposing forces. One region of their fin pushes water forward, while the other region pushes the water backward,” said Eric Fortune, a professor of biological sciences at the New Jersey Institute of Technology who was a co-author of the PNAS paper. “This arrangement is rather counter-intuitive, like two propellers fighting against each other.”

The research team developed a mathematical model that suggested that this odd arrangement enables the animal to improve both stability and maneuverability. The team then tested the accuracy of their model on a robot that mimicked the fish’s fin movements. This biomimetic robot was developed in the lab of Malcolm MacIver, an associate professor of mechanical and biomedical engineering at Northwestern University and a co-author of the PNAS paper.

“We are far from duplicating the agility of animals with our most advanced robots,” MacIver said. “One exciting implication of this work is that we might be held back in making more agile machines by our assumption that it’s wasteful or useless to have forces in directions other than the one we are trying to move in. It turns out to be key to improved agility and stability.”

The mutually opposing forces that help the knifefish become both stable and maneuverable can also be found in the hovering behavior of hummingbirds and bees, in addition to the glass knifefish examined in this study, said senior author Cowan, who directs the Locomotion in Mechanical and Biological Systems Lab within Johns Hopkins’ Whiting School of Engineering.

“As an engineer, I think about animals as incredible, living robots,” said study’s lead author, Shahin Sefati, a doctoral student advised by Cowan. “It has taken several years of exciting multidisciplinary research during my PhD studies to understand these ‘robots’ better.”

Other co-authors on the paper were Izaak D. Neveln and James B. Snyder, both Northwestern doctoral students in the Neuroscience and Robotics Laboratory supervised by MacIver; Eatai Roth, a former Johns Hopkins doctoral student now at the University of Washington; and Terence Mitchell; a former Johns Hopkins postdoctoral fellow now at the Campbell University School of Osteopathic Medicine.

This research was supported by three grants from the National Science Foundation, and by a grant from the Office of Naval Research.

 

Originally published here: http://hub.jhu.edu/2013/11/04/fishy-movement-solves-mystery.

Posted November 5th, 2013.

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A Female Guppy’s Mr. Right is One of a Kind

shutterstock_150200120

Photo Credit: Nantawat Chotsuwan/Shutterstock

Oct. 30, 2013 — When it comes to choosing a mate, female guppies don’t care about who is fairest. All that matters is who is rarest.

Florida State University Professor Kimberly A. Hughes in the Department of Biological Science has a new study just published in the journal Nature that is the first to demonstrate a female preference for rare males using an experiment in a wild population, rather than a laboratory setting.

This study of genetic differences in male guppies is relevant to understanding variation in humans as well as in other organisms, Hughes said.

Hughes and her longtime collaborators studied guppies in Trinidad and found that male guppies with rare color patterns mated more — and lived longer — than the common males. The males’ color variations are genetic and not due to diet or temperature. And the males’ actual appearance didn’t matter to the females, who are tan in color and do the choosing of mates.

“No matter which color pattern we made rare in any group, they mated more and had more offspring,” Hughes said.

So, a male guppy common in one grouping, i.e., placed in a stream with many fish that look like him, is a dud to the females also in the stream. But, take that common male and place him in a different stream with only one or two others similar to him, and he’s suddenly rare — and a desirable mate.

In an earlier study, Hughes showed that male guppies with rare color patterns had a survival advantage compared to those with common patterns in natural populations. During a three-week study, also in Trinidad, 70 percent of common males survived, while 85 percent of rare males survived.

This new study, “Mating advantage for rare males in wild guppy populations,” reports the results of paternity analyses of the offspring produced by the females in that earlier field experiment.

Hughes approached this new, rare-male-as-mating-champ theory with the goal of ruling it out. She thought it was unlikely.

But, “We got a big, significant result,” she said.

Guppies (Poecilia reticulata) are an ideal species for this study, Hughes said, because the males’ color variations are so visible and because there is so much variation. Other fish show color variation but not as widely as the guppy.

“These guys are sort of the champions of variation,” she said.

And it’s not that the rare males are simply trying harder to land a female. All male guppies do elaborate mating rituals, fanning out their fins and pursuing a mate.

The next question to answer, Hughes said, is why. Why do female guppies go for the rarest male in a particular population? It’s possible that in choosing a mate who appears unknown to her, a female guppy is trying to avoid procreating with a relative, which can lead to genetic disorders in offspring.

The guppy question speaks to a longstanding puzzle within evolutionary biology: Why are individuals within species so genetically diverse?

Understanding why species are genetically diverse is key to understanding human variation in disease susceptibility, for maintaining healthy crop and livestock populations and for preserving endangered species, Hughes said.

Hughes’ collaborators in this study are Anne E. Houde of the Lake Forest College Department of Biology in Lake Forest, Ill., and Anna C. Price and F. Helen Rodd of the Department of Ecology and Evolutionary Biology at the University of Toronto in Toronto, Ontario, Canada. Their work was supported by grants from the National Science Foundation and the Natural Sciences and Engineering Research Council of Canada.

Originally published here.

Posted November 1st, 2013.

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Aeronautics Used Underwater!

BY ROB JORDAN

coral reef

Dan Griffin, Stanford aeronautics graduate student Ved Chirayath photographs coral reefs from below the water using a 360-degree camera.

Like undiscovered groves of giant redwoods, centuries-old living corals remain unmapped and unmeasured. Scientists still know relatively little about the world’s biggest corals, where they are and how long they have lived.

The secret to unlocking these mysteries may lie with a shoebox-size flying robot.

The robot in question is a four-rotor remote-controlled drone developed by Stanford aeronautics graduate student Ved Chirayath. The drone is outfitted with cameras that can film coral reefs from up to 200 feet in the air. Chirayath teamed up with Stanford Woods Institute Senior Fellow Stephen Palumbi to pioneer the use of drone technology to precisely map, measure and study shallow-water reefs off Ofu Island in American Samoa.

“Until now the challenges have been too high for flying platforms like planes, balloons and kites,” Palumbi said. “Now send in the drones.”

Chirayath, who also works as a scientist at NASA’s Ames Research Center, analyzes the drone’s footage using software he designed. The software removes distortions caused by surface wave movements and enhances resolution. To link the drone aerial footage to close-up images of corals, Chirayath and his colleagues are photographing reefs from below the water using a 360-degree camera. The result is a centimeter-scale optical aerial map and stunning gigapixel panoramic photographs of coral heads that stitch together thousands of images into one.

 Surveys and maps of rainforests have resulted in new understanding of the vital role these ecosystems play in sustaining the biosphere. Detailed coral maps could do the same, allowing scientists to conduct precise species population surveys over large areas and assess the impact of climate change.

Rob Jordan is the communications writer for the Stanford Woods Institute for the Environment.

For more, please visit http://news.stanford.edu/news/2013/october/coral-reefs-drones-101613.html.

Posted October 21st, 2013.

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Just another way of Regenerating Tissue?

Spiked structures on male zebrafish pectoral fins are important for mating but also produce a potent signaling inhibitor. Presence of this inhibitor disrupts regeneration of fin tissue after amputation injury. (Credit: Developmental Cell, Kang et al.)

New research on the reproductive habits of zebrafish offers an explanation as to why some animals’ bodies repair tissues. The research team previously noticed that male zebrafish regenerate their pectoral fins poorly, as compared to females. Their latest findings, publishing in the October 14 issue of the Cell Press journalDevelopmental Cell, reveal the basis for this sex-specific regenerative deficiency: structures that are used to improve reproductive success. The scenario represents an example of the tradeoffs between reproduction and survival.

Led by first author Junsu Kang, the scientists identified anatomical structures that male fish use during mating that produce a signal that impedes regeneration of the pectoral fins after injury. As such, fish appear to trade an ancient ability to regenerate tissue easily for a new-found way of enhancing reproductive success. This valuable information could help scientists begin to explain why humans are less able to regenerate tissue and could also be used to improve the body’s tissue regenerative capacity.

“We discovered that male zebrafish have a very important set of structures on their pectoral fins that they use for breeding and that these structures secrete a potent molecular inhibitor of a key signaling pathway to aid their cycles of regular replacement,” explains senior author Kenneth Poss of Duke University Medical Center.

Higher vertebrates like mammals generally have a diminished capacity for tissue regeneration compared with lower vertebrates like fish and salamanders. “The biology we describe here suggests a new paradigm for how tissue regenerative capacity may be lost during species evolution,” says Poss. The researchers speculate that natural selection acting on traits like sexual features could have detrimental effects on tissue regenerative potential. For example, male zebrafish with more numerous or more effective breeding ornaments — and thus lower regenerative potential — might contribute more to the gene pool, phasing out regenerative potential over generations.

Poss notes that growing attention in the field of tissue regeneration is being paid to factors that block signaling pathways. “Our results indicate that the presence or restriction of a pathway inhibitor is critical to whether regeneration occurs normally, providing new fuel for ideas of how to promote regeneration after injury in humans.”

Originally published http://www.sciencedaily.com/releases/2013/10/131014121741.htm.

Posted October 16th, 2013.

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