Purpose of rainbow shimmer is unknown

From the darkness of a fish tank comes a blur of movement, followed by shimmering rainbow light.

That’s what it looks like when ghost catfish go for a swim.

The species appear transparent, or clear, at first, but as they move, the fish begin to glow with a rainbow light.

A new study found why: Ghost catfish reflect light from within.

That’s different from other animals that change colours as they move.

Those animals reflect light off outer surfaces like feathers and scales.

What is a ghost catfish?

Ghost catfish are a species of fish with no scales.

They measure just a few centimetres in length. That’s a bit smaller than a paperclip.

Their exposed skin is so transparent that about 90 per cent of light can pass through.

Ghost catfish are sometimes called glass catfish because of their transparent skin. (Image credit: Qibin Zhao/The Associated Press)

Though they’re native to Thailand’s rivers, ghost catfish are sold in pet stores all over the world.

How do they make rainbows?

The muscles inside ghost catfish are able to bend light.

This produces a shimmering rainbow as the fish swim.

Their muscles move as they swim, resulting in flashes of colours that look like a shimmering rainbow.

This process was discovered in a study led by physicist Qibin Zhao at the Shanghai Jiao Tong University in China.

The study was published in the Proceedings of the National Academy of Science journal on March 13.

Light passes through a ghost catfish in a fish tank, revealing a rainbow of colour. (Image credit: Xiujun Fan, Qibin Zhao/The Associated Press)

Why is this unique?

There are many iridescent animals that make a shimmer, such as beetles, hummingbirds, butterflies and other types of fish.

These species mostly reflect light off external skin, scales or feathers.

Ghost catfish are also iridescent, but they are different because they reflect light from inside their bodies.

In other animals, iridescence is often used to communicate warnings, according to biologist Ron Rutowski at Arizona State University.

But scientists still don’t know what purpose ghost catfishes’ rainbows serve.

Click play to see the ghost fish glow!

Check out these other animal news videos:

Have more questions? Want to tell us how we’re doing? Use the “send us feedback” link below. ⬇️⬇️⬇️

With files from The Associated Press
TOP IMAGE CREDIT: Qibin Zhao/Associated Press with graphic design by Philip Street/CBC

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Archaeologists are hearing for the first time how humans made music some 12,000 years ago, by recreating a flute that was likely used to hunt ducks and other small birds in northern Israel.

On Friday, a team of Israeli and French researchers published an article about the recreated bone flute in the peer-reviewed Nature Scientific Report, offering an auditory window into how early humans shifted from hunter-gatherers to more settled villages, creating the earliest known musical instruments ever discovered in the Middle East.

The French-Israeli team of archaeologists discovered fragments of seven different flutes, dating to around 10,000 BCE, which is the largest collection of prehistoric sound-producing instruments ever found in the Levant. The pieces were found at the Eynan/Ain Mallaha site, a small village some 35 km (20 miles) north of the Sea of Galilee. The site was inhabited from 12,000 BCE to 8,000 BCE, around the time when humans were undergoing a massive revolution from nomadic hunter-gatherers to more sedentary, semi-settled communities.

Dr. Laurent Davin, a post-doctoral fellow at Hebrew University, was examining some of the bones recovered from the site when he noticed tiny holes drilled at regular intervals along a few of the bones. At first, experts had dismissed the holes as regular wear and tear on the delicate bird bones. But Davin examined the bones more closely and noticed that the holes were at very even intervals, and clearly created by humans.

“One of the flutes was discovered complete, and so far as is known it is the only one in the world in this state of preservation,” Davin said in a press release that accompanied the article’s publication.

Dr. Hamoudi Khalaily, a senior researcher with the IAA, spent 10 years excavating at the Eynan site and was instrumental in creating a replica of the extant flute.

“There were a lot of doubts that this was even possible [to recreate], but the replica was created exactly [in the same way] as the original and it allowed us to hear what people would have heard 12,000 years ago,” Khalaily told The Times of Israel.

“When we first heard it, it gave us this feeling like, we are really doing something for history,” Khalaily said.

The recreated flute produces a screeching, breathy whistling sound that Khalaily and the team believe could be an imitation of predator birds, including falcons, which eat small waterfowl.

“The sound could have attracted predator birds, which creates chaos with the other birds, and then it’s very easy to catch them, even with your hands,” explained Khalaily.

Previously, nomadic hunter-gathers had focused on bigger game such as gazelles, rabbits, or foxes. But when humans began settling in the Hula Valley for the first time, they started taking advantage of new food sources, including fish and smaller waterfowl in the lake that used to stretch across the Hula Valley.

Today, the Hula Valley is still a major conduit for bird migration in the late fall when tens of thousands of birds pass through Israel on their way from Europe to Africa. The Hula Valley was once covered by water, with a 13 square kilometer (5 square mile) lake and 47 square kilometers (18 square miles) of seasonal swamps. Early Zionist pioneers drained the swamp in the early 20th century as a major infrastructure project to create more agricultural land and to combat malaria.

A trove of bird bones

At the Eynan site, archaeologists are excavating a small Natufian village, which was a Mesolithic culture in the Levant and Western Asia around 9000 BCE. It’s a unique time because the culture emerged when humans started living a semi-sedentary lifestyle predating the agricultural revolution, meaning they had to find regular food sources in the same area even before they knew how to cultivate them. Once humans became more settled, their culture underwent dramatic societal change including the appearance of burial practices, art, and durable structures.

The Eynan site was first excavated by a French mission in 1955 and later from 1996–2005 by a joint team from Israel and France directed by François Valla of the Centre Nationale de Recherche Scientifique (CNRS) and Khalaily of the Israel Antiquities Authority.

Excavations at the site are ongoing and it can take years to methodically sift through all of the earth removed from a site and search for fragments of tools, animal bones, or other detritus from daily life thousands of years ago. Over the past two decades, careful sifting has yielded 1,112 bird bones from the Eynan site.

The bone flute was researched and recreated by a team of French and Israeli experts, consisting of archaeologists and archaeozoologists, who study animal bones, ethnomusicologists, paleo-organologists (the research of ancient sound-making instruments), and technical experts that were able to find ways to recreate the exact placement of the finger holes.

The original flutes, also called aerophones because they are an instrument that produces sound due to vibrating air, were made from the hollow wing bones of the Eurasian teal and the Eurasian coot. The current replica was made from the wing bones of two female mallard ducks “because of the difficulty in obtaining carcasses of Eurasian coot (Fulica atra) used by the Natufians,” the article stated.

The tinier the bone, the more difficult it is to play. The researchers believe the bones were chosen specifically to mimic the calls of the Eurasian Sparrowhawk and the Common Kestrel, two birds of prey that were widespread in the Hula Valley.

The flute represents the oldest musical instrument found locally, but it is not the oldest aerophone that has been discovered. Most of the known Paleolithic sound-making instruments are found in Europe, and the oldest dates to around 40,000 years ago, which was found in southwestern Germany, made from bird bone and mammoth ivory.

Previous to this discovery, the only known “music” or sound production during the Paleolithic and Neolithic periods in the Levant was from a few studies suggesting that humans could have developed a belt of bone pendants that clacked and rattled, or possibly a bone whistle (flute with no fingerholes).

The flute represents an important discovery, but it’s not music to everyone’s ears.

“I heard it for the first time on Youtube, and it’s really a terrible tone, it’s high and pitchy and not nice at all to my ear,” said Prof. Rivka Rabinovich, the scientific director of archeozoological collections at the National Natural History Collections at the Hebrew University. Rabinovich, an expert in studying and interpreting the remains of ancient mammal bones has been studying the discoveries from the Eynan site for years.

Rabinovich added that there’s no way of knowing whether ancient humans had a similar cringe reaction when they heard it; whether it was used for hunting, communication, or making music.

But it opens a window into a fascinating point in human development, the complexity of society and their ability to make tools. The small finger holes in the flute were drilled with the talon of a larger bird, likely a falcon. Archaeologists believe that talons also had spiritual significance to early humans, Khalaily said.

“It’s very interesting because this is just at the starting point of people becoming more sedentary,” Rabinovich said. “It’s a very exciting period at which to understand the day-to-day life and also larger questions beyond day-to-day life, and why they did certain things.”

She credited the discovery to the large and varied French-Israeli team, which united researchers and archaeologists with areas of expertise in niche areas like reconstructing bone tools and interpreting scratches made in animal bones.

“The message from this is that you really need to save everything [excavated from a site] because you always see these things with new eyes and new tools,” she said. “It takes a long time to sift through things, and when you look at it anew, you can see it differently. That’s because there’s continually new research, there’s continually new technology, and new ways to investigate new information. And it all works together to create a more complete picture of what happened there.”

The Eynan site hosted continuous human presence for around 4,000 years, with people living in round houses made of stones with animal hides or branches for roofs. In 8,000 BCE, when the agricultural revolution was well underway, humans abandoned the site, moving around 500 meters closer to the Hula Lake, whose contours had changed with time.

One of the most important tests on the flute is yet to come: In late fall, when the annual bird migration through the Hula Valley takes place, Khalaily plans to take the replicated flute to the Eynan site and play it there, in the same spot where humans created it 12,000 years ago.

“I want to go and see if we can make these voices, in hopes of attracting a hawk or falcon,” he said. “I’m naturally an optimistic person, but I do really think it will work. If we were able to replicate this sound, I’m certain it will bring those birds to us.”

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Most galaxies exist in groups or clusters with dozens or hundreds of members, and these cluster galaxies are all in constant motion, pulled and twisted by their neighbour’s gravity. Galaxies exist in the vastness of space, consisting of various celestial objects such as stars, clouds of dust, and gas, all of which are bound together by gravity. These galaxy clusters are the largest objects in the Universe bound by gravity and astronomers can use them to measure important cosmological properties, according to NASA.

Today’s NASA Astronomy Picture of the Day is a snapshot of Abell 2744, also known as the Pandora’s Cluster of galaxies which is located about 4 billion light-years away towards the constellation of Sculptor. This galaxy cluster formed when four smaller galaxy clusters piled up nearly 350 million years ago, according to NASA. Shockingly, the galaxies in this cluster only account for 5 percent of its mass while dark matter inside it accounts for nearly 75 percent!

Tech used to capture the picture

This awesome snapshot was captured by the NIRCam instrument aboard the James Webb Space Telescope (JWST). It is operated by NASA in collaboration with ESA and is used to capture various celestial objects in stunning detail with the help of its suite of highly advanced instruments and cameras.

It also has sophisticated instruments like the Near Infrared Camera (NIRCam) which is the primary camera onboard the telescope. It has three specialized filters and captures images in two different infrared ranges. NIRCam also has coronagraphic and spectroscopic capabilities and is the primary tool for the alignment of the telescope. The space telescope also has Mid-Infrared Instrument (MIRI) and NIRSpec instruments onboard which aid in capturing mesmerizing snapshots of objects in space.

NASA’s description of the picture

This deep field mosaicked image presents a stunning view of galaxy cluster Abell 2744 from the James Webb Space Telescope’s NIRCam. Also dubbed Pandora’s Cluster, Abell 2744 itself appears to be a ponderous merger of three different massive galaxy clusters some 3.5 billion light-years away toward the constellation Sculptor. Dominated by dark matter, the mega-cluster warps and distorts the fabric of spacetime, gravitationally lensing even more distant objects.

Redder than the Pandora cluster galaxies many of the lensed sources are very distant galaxies in the early Universe, stretched and distorted into arcs. Of course distinctive diffraction spikes mark foreground Milky Way stars. At the Pandora Cluster’s estimated distance this cosmic box spans about 6 million light-years. But don’t panic. You can explore the tantalizing region in a 2 minute video tour.

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