The Earth Story

The red eye shine seen in alligators arises when light enters the eye and hits a layer of cells called the tapetum lucidum. This membrane is located beneath the photoreceptor cells (rods and cones) in the retina and reflects light back into these cells to increase the amount of light detected, which improves an alligator's vision in low light conditions. Several species exhibit this phenomenon, with different colour 'shines' observed. Most species with eyeshine are night hunters who must make use of limited light. -Jean Photos by Larry Lynch (http://www.lynchphotos.com/) and David Moynahan (http://www.davidmoynahan.com/)

Pygmy Mammoths, Cyclops and Greek Mythology

Many people have heard the tales of the terrible Cyclops; giants with a single eye that had a nasty tendency to kill, and sometimes eat, unsuspecting adventurers. However, conjuring up such fearsome beasts may not have been purely a feat of imagination; their origins may have been based on fact.

This story begins with the Mediterranean Islands during the Pleistocene, when low sea levels allowed land bridges to be exposed and for fauna to cross between land masses. Both elephants and mammoths roamed the Mediterranean with several species living side by side. However, at the end of the Ice Age, melting ice led to a sudden sea level rise, destroying any land bridges and isolating any individuals unfortunate to find themselves stuck on the island.

A lack of food led to an evolution bias in the elephant (Sardinia is the only island to have Mammoths) populations, with smaller individuals more successful as they required less food to survive. Over several generations this led to elephants/mammoths that could be as small as 1m at the shoulder.

So how do the cyclops come into this? Well, when the animals died they were stripped of all their soft tissue, but parts of their skeleton were preserved. The trunk of an elephant contains no bones and therefore is rarely found. This leaves the skull looking like the image below. Which oddly enough looks just like a huge skull with a single eye socket, especially if the specimen in question had lost its tusks.

Greeks coming to the island subsequently found these preserved skulls, often separated from any other bones or remains, and hypothesised to what they could be. They came to the conclusion these skulls had belonged to giant men with a single eye in the centre of their forehead and the myth of the cyclops was born.

Image Credit: Darren Copley

Reference: http://bit.ly/1PaBTr7

Further Reading: http://bit.ly/1DbTqHE

The Evolution of the Vertebrate Eye

The eye is one of the most complex organs across all taxa. Variations of it occur in 96% of animal species through all animal phyla, and is known to have evolved independently multiple times.

The origin of the vertebrate eye remained a mystery in the 1800s as it seemed something particularly complex could not be made by natural selection as it was understood in its early years. Darwin himself wrote that it was "... absurd in the highest possible degree," but continued to say that "Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist." Since those days, science has allowed a better understanding of how the eye came to be through gradual steps.  So, what were these gradual steps? The evolution of the eye begins on the cellular level with an organ as simple as a light-sensitive area. This light directs cells such as plant cells to a place where light is available for photosynthesis, or a microscopic multicellular animal may sense a shadow overhead and know to take cover from a predator. Over time, this light spot gradually became concave, allowing for the ability to detect the direction the light came from. This would have increased survivalship of the individuals because it allows them to travel away from predators or toward prey. The curvature became deeper, and the light spot began receding into the body, leaving only a pin-hole sized opening. This opening became covered by a transparent film, the eye filled with fluid, and finally, a lens was developed that allowed for the focusing of images at varying distances. Eventually other traits developed such as the pupil for light-control, eyelids, tear ducts, night vision, etc.

For a more detailed explanation:https://www.youtube.com/watch?v=qrKZBh8BL_U

~Rosie

Image: http://bit.ly/1ynxNYo

Reference: http://bit.ly/1IWovCT

Eye of the desert

In 1980, artist Tom Van Sant made the Mojave Desert wink. As part of an effort to celebrate the bicentennial of the city of Los Angeles, the artist was commissioned to produce this image in the desert using the Landsat 3 spacecraft.

This image, supposed to resemble an eye, was created using a series of 90 perfectly positioned mirrors. The artist worked with scientists from theUSGS and Stanford to calculate the exact position of each mirror by including the rotational speed of the earth, the velocity of the spacecraft, and the position of the sun.

Each mirror had to be accurately positioned to better than 1/10th of a degree in order to produce the over-exposure effect on the spacecraft's camera. Each mirror was only 2 feet by 2 feet square, and the mirrors covered an area 2.5 kilometers wide.

-JBB

Image credit: NASA/USGS/Landsat http://landsat.gsfc.nasa.gov/?p=9153

Opabinia One of the strangest creatures to ever live, Opabinia is known mainly from the Burgess Shale (see post athttp://on.fb.me/Riw7KU). The strangeness starts with the five eye stalks that protruded from the top of Opabinia's head. Its other most famous feature was the elephant trunk-like proboscis that seemingly delivered food to its backward-facing mouth found at the bottom of the head. -Mr. A Read more at https://en.wikipedia.org/wiki/Opabinia

In the eye These incredible frames were taken on Tuesday by CDR Kibbey on board a flight of what is known as the “Hurricane Hunters”. These flights, run by the US National Oceanographic and Atmospheric Administration, literally take planes and fly them into hurricanes. As they go, they collect data on air pressure, rain, and wind speed – coupled with satellite measurements data from these planes gives us our key constraints on the strength of major Atlantic Cyclones. Apparently this view from inside the eye, with the clouds of the eyewall towering around all sides, is nicknamed the Stadium View. This plane was literaly in the middle of the eye of Hurricane Irma when these were taken. -JBB Image source: http://bit.ly/2eEdnUs

The Process of Hurricane Landfall

As the immensely powerful Hurricane Irma tears through the islands of the Caribbean, now seems as good a time as any to discuss the behavior of hurricanes as they cross over coastlines onto land. Since the greatest impacts at landfall occur in and near the eyewall, let’s begin our discussion there.

The sometimes-cloudless center of rotation of a hurricane (most commonly referred to as the “eye”) has on its periphery the “eyewall,” a structure containing the most intense rains and winds in the entire storm (see the example of Jeanne from 2004, making landfall not far from where Matthew is forecast to hit). However, even a well-developed, highly symmetric eyewall is not an equal-opportunity destructive force, as the diagram below illustrates. In the Northern Hemisphere, a hurricane’s right-front quadrant (the northeastern quarter of the storm) contains the most forceful winds because the motion of the storm itself contributes to these wind speeds. As a direct result of these more intense winds, hurricanes are usually able to accumulate the greatest amount of water on their NE sides as well, leading to maximum storm surges occurring slightly to the east of the center of landfall.

While the aggregate effects of high winds, heavy rains, and storm surge can obviously result in terrible damage, the winds themselves are often not as severe as advertised. This isn’t a product of media hype – rather, it’s a result of friction. The wind speed attached to a hurricane represents the maximum sustained wind anywhere in the storm while it’s over water. Therefore, a “140mph (225kph) hurricane” may only be producing 140mph winds over a small area, and these winds begin decelerating when they start interacting with objects that slow their momentum (land, buildings, trees, etc.). Unfortunately, much of this kinetic energy from the slowing wind is transferred to objects on the ground, resulting in snapped trees, airborne debris, and damaged buildings.

As a storm’s center spends more time near or over land, the storm continues to weaken. The effects of friction continue to accumulate, slowing the storm’s wind and rotation. Moreover, the loss of warm ocean waters beneath the hurricane’s thunderstorms means that its chief source of energy is lost, and the intensity of its rains and winds further decrease. Even large and powerful major hurricanes survive for just a handful of hours to perhaps a day or so over land. 

--BRC

References: http://bit.ly/2dhHRJu http://bit.ly/1okC0TP Image credit: http://bit.ly/2dvGQ3o http://bit.ly/2e5SCCH

Fluorescing flowers

Insect's eyes can see in UV wavelengths, giving them a wider view of life than us creatures with a narrower colour range. Not surprisingly, some of their signals (eg wing patterns) also fluoresce in UV light, but so also do the flowers that largely depend on them for pollination. To our eyes, the flowers and leaves reflect one colour, the one they don't absorb (eg green for leaves), but to theirs there may well be an extra dimension that we do not perceive (like so much of the Universe around us). When plants absorb UV light, they also fluoresce, a process whereby it absorbs the high energy UV wavelengths and then gives the energy off as visible wavelengths as the electrons get charged and jump up and down in their orbits. The resulting photos are long exposures taken under a UV light over a black cloth, and reveal a new beauty to the botanical world.

Loz

Image credit: Craig Burrows 1: Juvenile blanket flower, 2: Bee balm, 3: Dandelion, 4: Ice plant buds, 5: Narcissus Craig's website: http://www.cpburrows.com/ http://bit.ly/2m7XiYH

Scientists in Australia have discovered the fossilised eyes of a prehistoric "super predator" Anomalocaris in rocks on the coast of Kangaroo Island, South Australia. The predator lived in Cambrian seas. The eyes of Anomalocaris measured 3cm across and had 16,000 individual lenses! Anomalocaris was a shrimp like creature measuring up to 1m across, and are currently considered to have been at the top of the ancient marine food chain. The find shows that the creature lived in clear, well-lit waters and it is believed that the eyes evolved rapidly, possibly triggering an evolutionary arms race with other marine species. http://bit.ly/KkbF5G -LL

Light

Photographer Daniel Gaussen sent us this shot of the Milky Way captured above the peaks of Queensland, Australia, last July, and added this text describing the time when the shot was taken.

“So technical details: Canon 600D (astro modified) with a Samyang 16mm lens @ F 2.0 . The camera was piggy-backed on a Skywatcher HEQ5 pro tracking mount to counteract the rotation of our planet and reduce star trailing allowing me to expose the galaxy for 1 minute. It was taken in Queensland, Australia high on Mt. Tambourine. With the naked eye the dark and elusive dust lanes were clearly visible, brought out by a contrasting backdrop of hazy, ghostly light produced by the billions of distant suns that spanned out in front of me. It resembled an eerily glowing white cloud hanging across the sky, cold and distant yet beautiful and humbling. The camera gathered up light produced by these distant suns revealing such a much deeper and detailed view...

The light from those stars traveled for up to thirty - thousand years before happening to collide with my tiny camera. When we look into the Milky Way we see thousands of years into the past across unimaginably vast expanses of space and time toward the dense core of our ancient spiral galaxy.”

-JBB

Photographers’ Flickr Page: https://www.flickr.com/photos/130223747@N03/

I...cannot do this.

The Process of Hurricane Landfall

As the immensely powerful Hurricane Matthew (Category 4 as of this writing) tears through the Bahamas and bears down on Florida, now seems as good a time as any to discuss the behavior of hurricanes as they cross over coastlines onto land. Since the greatest impacts at landfall occur in and near the eyewall, let’s begin our discussion there.

The sometimes-cloudless center of rotation of a hurricane (most commonly referred to as the “eye”) has on its periphery the “eyewall,” a structure containing the most intense rains and winds in the entire storm (see the example of Jeanne from 2004, making landfall not far from where Matthew is forecast to hit). However, even a well-developed, highly symmetric eyewall is not an equal-opportunity destructive force, as the diagram below illustrates. In the Northern Hemisphere, a hurricane’s right-front quadrant (the northeastern quarter of the storm) contains the most forceful winds because the motion of the storm itself contributes to these wind speeds. As a direct result of these more intense winds, hurricanes are usually able to accumulate the greatest amount of water on their NE sides as well, leading to maximum storm surges occurring slightly to the east of the center of landfall.

While the aggregate effects of high winds, heavy rains, and storm surge can obviously result in terrible damage, the winds themselves are often not as severe as advertised. This isn’t a product of media hype – rather, it’s a result of friction. The wind speed attached to a hurricane represents the maximum sustained wind anywhere in the storm while it’s over water. Therefore, a “140mph (225kph) hurricane” may only be producing 140mph winds over a small area, and these winds begin decelerating when they start interacting with objects that slow their momentum (land, buildings, trees, etc.). Unfortunately, much of this kinetic energy from the slowing wind is transferred to objects on the ground, resulting in snapped trees, airborne debris, and damaged buildings.

As a storm’s center spends more time near or over land, the storm continues to weaken. The effects of friction continue to accumulate, slowing the storm’s wind and rotation. Moreover, the loss of warm ocean waters beneath the hurricane’s thunderstorms means that its chief source of energy is lost, and the intensity of its rains and winds further decrease. Even large and powerful major hurricanes survive for just a handful of hours to perhaps a day or so over land. With a storm like Matthew, we can only hope that its projected track grinding along the coast will lead to a quick demise.

--BRC

References: http://bit.ly/2dhHRJu http://bit.ly/1okC0TP Image credit: http://bit.ly/2dvGQ3o http://bit.ly/2e5SCCH

Fossil eye pigments offer a window into evolutionary history

Over the last couple of decades modern technology has become increasingly sophisticated in its ability to tell us cool stories about our world, and knowledge just squeezed out of lamprey eyes that saw the light of the late Carboniferous of 300 million years ago has shown that complex eyes have been around for a long time. Trying to trace the history of soft parts is tricky, requiring an uncommon degree of preservation in the fossils and a good deal of sheer ingenious sweat, mental and physical, hence the value in this paper recently published in the Proceedings of the Royal Society. Eyes have been a big topic of evolutionary debate since Darwin first published his ideas, and they have evolved several times in different models during the course of evolutionary history.

Lampreys and hagfish are proto vertebrates and some of the earliest complex chordates (a phylum that includes us), with a notochord of nervous tissue unprotected by the vertebrae that keep our spinal tissue relatively safe. Primitive chordates include species without eyes, at best only having a light sensitive patch at one end (eg the sea squirts), while most vertebrates have complex eyes with lenses, irises and controlling muscles backed by a retina on which the image is projected for transmission to the brain. Modern retinas contain the dark pigment melanin in order to absorb reflections and stop light rays bouncing around inside the eye and confusing the picture focussed onto the light sensitive proteins.

Lampreys nowadays are somewhere in between, with a complex eye but no spine, whilst hagfish have none, and similarly lack pigment granules in their retinas, so whether are hagfish a missing link has long been a contentious subject. A team decided to study pigments in fossil eyes in a specimen of each group preserved in the Mazon Creek locale in Illinois.

They managed to examine them in much greater detail than ever before, showing that the fossil hagfish had well developed complex eyes with pigmented retinas, showing that they have in fact been lost somewhere in evolutionary history by their descendants, rather than representing a missing link between eyes and not eyes, requiring a refinement of the quest for the intermediary forms, if they ever existed and were preserved in the geological lottery of fossilisation.

Loz

Image credit, Short-Headed Lamprey, a jawless fish found in Australia and one of the closest living relatives of the fossils under discussion: Ho/Reuters:

http://bit.ly/2cTY7mu http://bit.ly/2d2QRp4 http://bit.ly/2cJOl5R Original paper, paywall access: http://bit.ly/2aQQuOl