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Glass frogs, ghost shrimp and clearwing butterflies use transparency to evade predators –



This article, written by James B. Barnett, McMaster University, originally appeared on The Conversation and has been republished here with permission:

What would you do if you could be invisible? Would you use your power for good? For evil? Or just to avoid awkward conversations?

Transparency may seem like the simplest form of camouflage, but in the last year, research has revealed new complexities behind what some animals do to vanish into their surroundings.

In my research, I have experienced first-hand how effective and sophisticated transparency really can be. That story begins on a dark night in the pouring rain in the thick of French Guiana’s tropical rainforest.

My colleagues and I could only see as far as the beams of our headlamps would permit. We scanned the branches overhead for the source of a strange, high-pitched chirp: an almost metallic sound cutting sharply through the nightly cacophony of buzzing, rasping and squeaking.

Finally, our headlamps revealed a pair of googly eyes peering down on us, and we knew we had found what we had been searching for: a tiny glass frog (Teratohyla midas), only a couple of centimetres long. These bizarre frogs have transparent skin that lets us look directly at their intestines and bones — even at their beating hearts.

Transparent, not invisible

Glass frogs are an amazing sight but seeing one raises an interesting question: what’s the point of having transparent skin if your predators can still see you, or your internal organs?

Let’s take a step back to see how transparency works and understand why we’re not constantly bumping into invisible creatures. Although transparency seems like an obvious type of camouflage — if that’s not too much of a contradiction in terms — becoming transparent is not easy.

We can see what’s around us because of how different objects interact with light. If something is opaque, light is either reflected or absorbed at its surface. For something to be transparent, light must instead travel straight through it.

But as light moves between transparent materials it can be bent and scattered. Think about how a straw in a glass of water appears to bend. This is refraction, and results from the different ways that light moves through air and water.

An animal’s body is made up of many organs and tissues, each with a different thickness, structure and chemical makeup. For the animal to be transparent, light must not be reflected, absorbed, scattered or refracted as it travels through each of these different layers.

Water-dwelling animals are at a clear advantage in terms of achieving transparency. Animal bodies are mostly made of water, and if a creature is already in the water, there is much less refraction and scattering of light. As a result, some of the most effective examples of transparency are oceanic species like jellyfish and shrimp.

On land, transparency is much rarer, but we are now learning that it can be very effective, sometimes in unexpected ways.

Clearwing butterflies, for example, are not bound by the colours and patterns other butterflies use to blend into specific backgrounds. Instead, their fully transparent wings mean that predators look straight through them, and they can blend effectively into any background.

Several large moth species have taken a different route. Instead of making the whole wing transparent, their wings have transparent panes that allow patches of the background to show through. By combining these transparent panels with opaque colours, the wing surface is broken up and the moth transformed into an unrecognizable mosaic.


So, what of our little transparent frogs back in the rainforest? Here, transparency provides yet another form of camouflage. Unlike butterflies and moths with their transparent wings, these frogs have all of their internal organs on show, preventing true transparency. Instead, by combining their transparent underside with a green topside, the frogs become translucent: allowing some light through but not showing a clear image.

Their green colouring is a close match to that of a generic leaf, and the trick of translucency allows the frog to brighten or darken in keeping with the leaves around it. What’s more, the frogs’ legs are more translucent than their bodies, providing an extra advantage from a process called “edge diffusion,” further blending frog and leaf together in the eyes of its predators.

Transparency makes animals hard to find, but there are many ways for animals to achieve invisibility.

Understanding how animals evade detection can help us protect species as humans continue to change the natural world around us.

James B. Barnett, Postdoctoral Fellow in Behavioural Ecology, McMaster University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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NASA rover Perseverance takes first spin on surface of Mars – Global News



NASA’s Mars rover Perseverance has taken its first, short drive on the surface of the red planet, two weeks after the robot science lab’s picture-perfect touchdown on the floor of a massive crater, mission managers said on Friday.

The six-wheeled, car-sized astrobiology probe put a total of 6.5 meters (21.3 feet) on its odometer on Thursday during a half-hour test spin within Jezero Crater, site of an ancient, long-vanished lake bed and river delta on Mars.

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Taking directions from mission managers at NASA’s Jet Propulsion Laboratory (JPL) near Los Angeles, the rover rolled 4 meters (13.1 feet) forward, turned about 150 degrees to its left and then drove backward another 2.5 meters (8.2 feet).

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“It went incredibly well,” Anais Zarifian, a JPL mobility test engineer for Perseverance, said during a teleconference briefing with reporters, calling it a “huge milestone” for the mission.

NASA displayed a photo taken by the rover showing the wheel tread marks left in the reddish, sandy Martian soil after its first drive.

Click to play video 'Perseverance rover: Scientist on when we can expect samples back from Mars'

Perseverance rover: Scientist on when we can expect samples back from Mars

Perseverance rover: Scientist on when we can expect samples back from Mars – Feb 19, 2021

Another vivid image of the surrounding landscape shows a rugged, ruddy terrain littered with large, dark boulders in the foreground and a tall outcropping of rocky, layered deposits in the distance – marking the edge of the river delta.

Some additional, short-distance test driving is planned for Friday. Perseverance is capable of averaging 200 meters of driving per day.

But JPL engineers still have additional equipment checks to run on the rover‘s many instruments before they will be ready to send the robot on a more ambitious journey as part of its primary mission to search for traces of fossilized microbial life.

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So far, Perseverance and its hardware, including its main robot arm, appear to be operating flawlessly, said Robert Hogg, deputy mission manager. The team has yet to conduct post-landing tests of the rover‘s sophisticated system to drill and collect rock samples for return to Earth via future Mars missions.

NASA announced it has named the site of Perseverance’s Feb. 18 touchdown as the “Octavia E. Butler Landing,” in honor of the award-winning American science-fiction writer. Butler, a native of Pasadena, California, died in 2006 at age 58.

(Reporting by Steve Gorman, Editing by Rosalba O’Brien)

© 2021 Reuters

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NASA's new Mars rover Perseverance hits dusty red road, ventures 21 feet in 1st trip – Chilliwack Progress – Chilliwack Progress



NASA’s newest Mars rover hit the dusty red road this week, putting 21 feet on the odometer in its first test drive.

The Perseverance rover ventured from its landing position Thursday, two weeks after landing on the red planet to seek signs of past life.

The roundabout, back and forth drive lasted just 33 minutes and went so well that the six-wheeled rover was back on the move Friday.

During a news conference Friday, NASA’s Jet Propulsion Laboratory in Pasadena, California, shared photos of the tire tracks over and around small rocks.

“I don’t think I’ve ever been happier to see wheel tracks and I’ve seen a lot of them, said engineer Anais Zarafian. ”This is just a huge milestone for the mission.”

As soon as the system checks on Perseverance are complete, the rover will head for an ancient river delta to collect rocks for return to Earth a decade from now. Scientists are debating whether to take the smoother route to get to the nearby delta or a possibly tougher way with intriguing remnants from that once-watery time 3 billion to 4 billion years ago.


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Asteroid twice the size of the CN Tower to make fastest flyby of Earth this month – CTV News



The biggest and fastest known asteroid of 2021 is expected to make a flyby of Earth later this month.

The space rock, officially called asteroid 231937 (designated 2001 FO32), will zoom past Earth on March 21 travelling at a speed of 123,887 kilometres per hour or 34.4 kilometres per second, according to NASA.

The asteroid is an estimated 1.1 kilometres wide, which is roughly twice the size of the CN Tower. Of the approximately 25,000 near-Earth asteroids that scientists know about, NASA says only about 3.5 per cent of them are larger than a kilometre.

Due to its size and proximity to Earth, asteroid 231937 has been classified as “potentially hazardous” by NASA’s Center for Near-Earth Object Studies (CNEOS) and is being tracked by the space agency.

NEOs are defined as space objects, such as asteroids or comets, that come within 1.3 astronomical units (195 million kilometres) of the sun. If the object is larger than 140 metres across, it is considered a potentially hazardous object (PHO).

Nearly one hundred known asteroids are set to fly past Earth before the end of 2021, NASA says, but asteroid 231937 is set to be the largest and fastest.

However, NASA says the asteroid’s orbit is well known and poses no threat to humans.

According to the space agency, the asteroid will make is closest approach at 16:03 UTC (11:03 a.m. EST), at over two million kilometres away from Earth. NASA notes that this is nearly five times farther than the distance the moon orbits Earth.

Despite being two million kilometres away, NASA says this will be the asteroid’s closest encounter on record. According to NASA’s records dating as far back as the early 1900s, the space rock has not come closer to Earth and won’t do so again for 200 years.

Asteroid 231937 was discovered on March 23, 2001, by the Lincoln Near-Earth Asteroid Research program in New Mexico, according to NASA. It orbits the sun every 810 days and is classified as an Apollo asteroid as it travels from inside Mercury’s orbit to the asteroid belt and back, crossing Earth’s orbit in an elliptical pattern.

While those interested in catching a glimpse of the asteroid won’t be able to do so with their eyes, EarthSky reports that stargazers may be able to see it using a telescope 20 centimetres or larger in diameter to detect the asteroid’s motion in real time.

The asteroid will be relatively low in the southern sky, but EarthSky said observers might spot it moving between the constellations of Scorpius and Sagittarius just before dawn.

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