A Japanese pufferfish makes an extraordinary sand sculpture to attract and win a mate.
(BBC)
(BBC)
Links :
Saturday, April 8, 2017
Friday, April 7, 2017
Squishy robotic manta ray flaps its wings to spy in the ocean
A soft-bodied robot that swims like a manta ray has been engineered to spy on underwater creatures without disturbing them.
From New Scientist by Alice Klein
It’s a drone of the deep.
A soft-bodied robot that swims like a manta ray has been engineered to spy on underwater creatures without disturbing them.
The mostly transparent robot has no motor or other rigid machinery and is much faster than other soft robotic fish.
The goal is to use the robot to explore underwater areas, says Tiefeng Li at Zhejiang University in Hangzhou, China.
It could be used to investigate a submerged ship or plane wreck, or survey coral reefs.
“The soft body will make it easy for the robot to sneak through reefs without damaging them,” he says.
Robots are increasingly being constructed from soft, stretchy materials to make them more resilient and more compatible with living beings.
However, powering them without traditional hard-edged circuit boards and motors is a challenge.
Manta ray : a natural source of inspiration
A silicone-encased lithium battery supplies a cyclic voltage that squeezes and releases that material, causing the muscles to bend up and down.
This flaps the ray’s fins, made of a thin silicone film, so that it moves through the water.
The rest of the remotely controlled robot – which weighs 90 grams and has a wing span of 22 centimetres – is made of a silicone body and tail for steering.
All components are transparent, except for the small battery pack and two electromagnets that help to manoeuvre the tail.
The soft robot inspired by the manta ray.
Image: Li et al
Soft but spritely
At top speed, the robot can swim 6 centimetres per second.
This beats the previous record for soft, untethered underwater robots by 3 centimetres per second, but is still significantly slower than similar-sized fish.
The researchers showed that the electronic ray can tolerate temperatures between 0.4°C and 74°C, swim for 3 hours with a single battery charge, and carry a small video camera to monitor its surroundings.
The flexibility and transparent disguise of the robot ray should allow it to monitor underwater environments without disturbing or damaging them, says Li.
“Ocean creatures will feel more comfortable with it than hard, non-transparent robots,” he says.
The underwater electronics do not pose an electrocution risk to ocean life because the robot’s circuitry is set up so the surrounding water functions as the grounding electrode – the end that dissipates electrical energy.
“This is a very good idea,” says Gursel Alici at the University of Wollongong in Australia.
A previous project (2012)
A robotic ray tested in the deep end of UVA's Aquatic Fitness Center pool.
see Bart-Smith Labs
Although other types of robotic swimmers have been made using soft parts – including ones that mimic octopuses, fish and jellyfish – the manta ray is a unique take on this concept, says Alici.
It remains to be seen whether it will have practical applications, he says.
Links :
- Engadget : Soft manta ray robot could watch over coral reefs
- Silicone public : New, tiny manta ray robots could one day hunt lakes for pollution
- Engineering : A Robot That Swims Like a Manta Ray
- GeoGarage blog : 'Mantabot' vehicle swims like a ray
- ScienceMag : Robotic stingray powered by light-activated muscle cells
Thursday, April 6, 2017
This small island nation makes a big case for protecting our oceans : In gorgeous Palau, explorers find wonders worth protecting
From National Geographic by Sarah Gibbens
Two years ago, Palau created one of the largest marine reserves on the planet—and it's paying off.
It stands to reason that if you protect the ocean, ecosystems will thrive.
Now, scientists have hard data to back up that logical assumption, thanks to a sweeping study of marine reserves in the island nation of Palau.
Palau island with the GeoGarage platform (NGA chart)
Nearly two years ago, Palau officially designated 193,000 square miles of its maritime territory as a fully protected marine reserve, where no fishing or mining can take place.
The reserve became the sixth-largest of its kind in the world—while the island of Palau is smaller than New York City, its marine protected area became larger than the state of California.
Palau's vibrant corals are thriving, despite some of the warmest and most acidic waters in the world. In this virtual reality experience, Lukas Isall from the Palau International Research Centre explains how unlocking the mystery of Palau's corals might help in the fight against climate change.
Now, science has confirmed the case: In a paper published March 30 in the journal PLOS ONE, researchers from the Fisheries Ecology Research Laboratory at the University of Hawaii report the results of their efforts set out to monitor just how much positive impact a marine protected area could have.
The Pristine Seas team surveyed a lake harboring millions of jellyfish Palau's greatest tourist attraction.
photo : Enric Sala, National Geographic Creative
Their study focused heavily on the amount of biomass—fish and so-called benthic organisms living on the sea floor—that were present in Palau’s protected areas.
To disturb the marine life as little as possible, the researchers didn’t take any samples and instead derived their results from photographs and direct visual estimates.
They found that protected waters had twice the number of fish as unprotected waters and five times the number of predatory fish.
As a key food source for other predators, a healthy fish population indicates a thriving ecosystem.
"What we measured confirmed that no-take marine reserves help increase the biomass of fish, as we've seen in other areas around the world," says Enric Sala, a National Geographic Explorer-in-residence who worked on the study.
Protected areas allow Palau’s fish to produce more offspring, which in turn produces a number of benefits for local fishers.
The study suggests that when biomass increases inside protected areas, the resulting spillover of adult fish populations into non-protected waters leads to more abundant catches for local fisheries.
Sala notes that this successful conservation was attributable not only to policy instated by the local government, but also to the culture of conservation among the island's inhabitants.
Palau is a collection of around 250 islands located in the Pacific Rex
The nation has no military with which to enforce regulations.
Instead, local conservation efforts evolved from a thousand-year-old tradition called bul.
The practice takes place when Palau's Council of Chiefs places certain reefs off limits to allow fish undisturbed space to breed and feed.
Heeding the sensitivity of fish during these periods ensured populations would be sufficient for feeding local communities at later times in the year.
In Gorgeous Palau, Explorers Find Wonders Worth Protecting
National Geographic Explorer-in-Residence Enric Sala led an expedition in September 2014 to document the stunning biodiversity of the Republic of Palau's waters and assess how a marine protected area could help safeguard the ecosystems of this paradise for generations to come.
National Geographic Explorer-in-Residence Enric Sala led an expedition in September 2014 to document the stunning biodiversity of the Republic of Palau's waters and assess how a marine protected area could help safeguard the ecosystems of this paradise for generations to come.
The expedition was part of National Geographic's Pristine Seas project.
It has one of the highest rates of biodiversity on the planet, and a significant portion of its economic revenue is generated by environmental tourism.
Of course, Palau isn’t the only country to benefit from healthy marine resources, and only 1.6 percent of the world's oceans are protected.
The researchers hope other governments will take notice of how beneficial these protected areas can be.
“We need as many more reserves as possible in remote and in populated places, large and not so large," saysid Sala. "There is no time to waste."
Correction: The area surveyed for this study took place off the coast of Palau.
The marine sanctuary is located farther offshore.
Scientists believe their findings in protected areas near Palau's populated regions mean the reserve will yield positive results.
Links :
- ScienceLine : Protecting the other two thirds of the globe
- GeoGarage blog : World's largest single marine reserve created in Pacific / Protection of our oceans must go hand-in-hand with the fight against climate change / Tiny Pacific island nations create world's largest marine ... / Jellyfish lake, Palau / Enric Sala: Saving the world's oceans one at a time
Wednesday, April 5, 2017
The 15th-century monk who crowdsourced a map of the World
Nat Williams, James and Bettison Treasures Curator at the National Library of Australia, discusses the Fra Mauro Map of the World.
Created by the monk Fra Mauro between 1390-1459, it is one of the most important and famous maps of all time and the crown jewel of the collections of the Biblioteca Nazionale Marciana in Venice.
If you had landed in Venice during the mid-15th century, you might have been accosted by a monk with a prominent nose and baggy, smurf-like hat.
Ignoring your exhaustion and atrocious body odor after a long sea journey, he would have dragged you to a nearby tavern and cross-examined you about your travels.
What was the weather like?
What kind of precious gems were mined?
What animals did you encounter, and how many heads did they have?
Map of the world by Venetian monk Fra Mauro.
The image shows a reproduction made by W. Fraser made in 1806.
The map is orientated with south at the top.
The Fra Mauro map, inverted according to the modern North-South orientation.
The monk was Fra Mauro, a 15th-century version of Google Earth.
Famous for his cartographic skills, he had been commissioned by King Alfonso of Portugal to produce a map of the world.
Earth according to Fra Mauro and the Blue Marble
courtesy of NASA
courtesy of NASA
The Portuguese were eager explorers and wealthy clients, and in the days before satellite imagery, Venice was a cartographers’ heaven.
Arab traders and world explorers passed through the port, giving Fra Mauro an incomparable source of gossip and tall tales about the world.
The fall of Constantinople, occurring a few years before the map was finished, would also have provided a rich source of well-traveled refugees, presumably willing to swap their stories for some bread or beer.
Crowdsourcing a map had never been easier, and Fra Mauro took full advantage.
He interrogated these travelers with an inquisitiveness verging on belligerence, cross-checking their tales against the extensive library in his monastery in the Venice lagoon.
He used their information to draw the map itself and pepper it with almost 3,000 annotations.
Some of the thousands of annotations on the map.
Fra Mauro loved a good story, and his map is packed with pictures of amber, rubies, pearls, diamonds, manna, and “other notable things”.
He was also fascinated by exotic animals and practices. Seven-headed serpents roam the province of Malabar in India, troglodytes run wild in East Africa, and the Barents Sea near Norway harbors fish that can “puncture the ships with a spike they have on their backs”.
More exotic treasures include a lake on an island in the Indian Ocean that can turn iron into gold.
In the accompanying annotation, Fra Mauro hastily explained that he didn’t believe a word of this story, and included it “just to do justice to the testimony of many people.”
Given that he repeated this particular tale in three different places and drew a spectacular gold lake in the middle of the Andaman Islands for good measure, his skepticism seems ambiguous to say the least.
Detail from Fra Mauro's map, a work of unprecedented thoroughness and accuracy.
To modern eyes, the monsters, lakes of honey-wine, and cannibals suggest credulity.
In fact, however, the annotations on the map are full of doubt and skepticism.
In both India and Africa, Fra Mauro gives no credence to the wild tales of “human and animal monsters,” noting that none of the travelers with whom he spoke could confirm the stories.
“I leave research in the matter,” he concluded sarcastically, “to those who are curious about such things.”
Fra Mauro’s depiction of Africa
Fra Mauro was also exceptional in his rejection of religious and classical authority.
Europe was not a haven of religious tolerance at the time; the Spanish inquisition started just 20 years after the map was completed.
Mapmakers, consequently, focused on keeping the Church happy rather than worrying about minor geographic details.
Medieval maps showed the location of Noah’s Ark, discussed the depravity of pagans, and illustrated the hideous giants Gog and Magog, lurking in the far North and eagerly awaiting the apocalypse.
Fra Mauro, by contrast, took a rigidly empirical approach.
The Garden of Eden was relegated to a sidebox, not shown in a real geographic location.
He sternly noted that the tradition that the Gog and Magog lived in the Caucasus Mountains “is certainly and clearly mistaken and cannot be upheld in any way,” since plenty of people lived in and traveled to the mountains, and they would have noticed any monstrous giants living nearby.
Adam and Eve made an appearance on the bottom-right corner of the map.
Fra Mauro also criticized various classical authorities.
Like a cheeky schoolchild—or a commentator on an online forum—Fra Mauro prefaced his criticism by saying that he didn’t want to seem contrary but couldn’t help it that everyone else was wrong. Ptolemy got the size of Persia wrong, mislabeled Sri Lanka, and didn’t realize that you could sail all the way around Africa.
Regarding the circumference of the Earth, Fra Mauro cited a couple of expert opinions and concluded dismissively that “they are not of much authenticity, since they have not been tested.”
His robust skepticism marked a transition away from medieval traditions towards the intellectual excitement of the Renaissance.
Comparison between Fra Mauro map (1450) and Da Ming Hun Yi Tu map (1389)
As a result, Fra Mauro’s map was the most accurate ever made at the time.
It wasn’t just his piercingly accurate national stereotypes; the Norwegians were “strong and robust,” while the Scottish were “of easy morals.”
He was the first to depict Japan as an island, and the first European to show that you could sail all the way around Africa.
The latter finding drew on reports from unfortunate traders blown by a storm ‘round South Africa, learning that it was circumnavigable and liberally endowed with 60-foot birds, capable of picking up elephants.
Through depicting the riches, navigation routes, and people around the world, Fra Mauro didn’t just describe terrain, but played a part in encouraging further exploration and analysis, leading up to the famous Age of Exploration and the discovery of the Americas.
Ships at sea on the map.
Modern interest in Fra Mauro’s map was sparked by Placido Zurla, a monk at the same monastery, who published a lengthy study in 1806.
Since then, it’s been widely recognized that Fra Mauro was way ahead of his time for his accurate geographical knowledge, willingness to challenge authority, and emphasis on empirical observation.
The map is accurate enough to guide researchers to as-yet undiscovered archaeological sites.
For example, Fra Mauro’s contacts in the Ethiopian Church allowed him to map medieval Ethiopia in surprising detail.
He accurately portrayed a number of geographical features; the Awash River, mountain ranges surrounding Addis Ababa, and the Ziquala mountain and monastery (which is still there, 500 years later).
Alongside geographical features, Fra Mauro plotted ancient cities that for centuries scholars assumed never existed.
This assumption is challenged by archaeologists today, who have found unmistakable signs of past habitation in the sites that Fra Mauro indicated.
Although no excavation has started, obsidian shards and pottery pieces litter the landscape, and small walls, old grindstones, and worn foundations are visible under moss and bushes.
If he were alive today, Fra Mauro would probably be disappointed to know that lakes of gold and wine existed just in the imagination of the travelers he interviewed.
He would, however, be happy to know that his map is proving more accurate than skeptical cartographers gave it credit for, and that it still acts as a starting point for research and discovery.
Links :
- Crossing the Ocean Sea : Fra Mauro’s Great Map of the World in Venice
- Cartographic images : Fra Mauro's Mappamundi
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