Disguise Master...

National Geographic

Photo of the Day

Eastern Screech Owl, Georgia

Photograph by Graham McGeorge

Masters of disguise. The eastern screech owl is seen here doing what they do best. You better have a sharp eye to spot these little birds of prey. Okefenokee Swamp, Georgia, U.S.A.

http://goo.gl/KYDRA

Mimic Octopus - The Great....

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 Description & Behavior

This fascinating creature was discovered in 1998 off the coast of Sulawesi in Indonesia on the bottom of a muddy river mouth. For the next 2 years, scientists filmed nine different mimic octopuses, Thaumoctopus mimicus (Norman & Hochberg, 2005), impersonating sea snakes, lionfish, and flatfish—a strategy used to avoid predators. Mimic octopuses reach about 60 cm in length and are typically brown and white striped.

Mimic octopuses have been observed shifting between impersonations as it crosses the ocean floor to return to its burrow.

Scientists speculate that additional mimic species will be found in muddy river and estuary bottoms in the tropics as these areas are typically unexplored.

All octopus species are highly intelligent and change the color and texture of their skin for camouflage to avoid predators. Until the mimic octopus was discovered, however, the remarkable ability to impersonate another animal had never been observed.

Norman and fellow researchers, Julian Finn of the University of Tasmania in Australia and Tom Tregenza of the University of Leeds in England, describe the mimic octopus in the September 7th issue of the Proceedings of the Royal Society of London.

Although mimicry is a common survival strategy in nature, certain flies assume the black and yellow stripes of bees as a warning to potential predators, the mimic octopus is the first known species to take on the characteristics of multiple species. The creatures they mimic include:

» Sole fish: This flat, poisonous fish is imitated by the mimic octopus by building up speed through jet propulsion as it draws all of its arms together into a leaf-shaped wedge as it undulates in the manner of a swimming flat fish.

» Lion fish: To mimic the lion fish, the octopus hovers above the ocean floor with its arms spread wide, trailing from its body to take on the appearance of the lion fish's poisonous fins.

» Sea snakes: The mimic octopus changes color taking on the yellow and black bands of the toxic sea snake as it waves 2 arms in opposite directions in the motion of two sea snakes.

Scientists believe this creature may also impersonate sand anemones, stingrays, mantis shrimp and even jellyfish.

This animal is so intelligent that it is able to discern which dangerous sea creature to impersonate that will present the greatest threat to its current possible predator. For example, scientists observed that when the octopus was attacked by territorial damselfishes, it mimicked the banded sea snake, a known predator of damselfishes.

World Range & Habitat

 OBIS Distribution map

Indo-pacific (Sulawesi and Bali in Indonesia), muddy estuary bottoms in the tropics.

Feeding Behavior (Ecology)

Because mimic octopuses, Thaumoctopus mimicus, are found in muddy river bottoms and estuaries, its diet most likely consists of small crustaceans and fish.

Astronomy Picture of the Day

2013 June 8 

Messier Craters in Stereo 

Credit: Apollo 11, NASA; Stereo Image by Patrick Vantuyne

http://apod.nasa.gov/apod/ap130608.html

Many bright nebulae and star clusters in planet Earth's sky are associated with the name of astronomer Charles Messier, from his famous 18th century catalog. His name is also given to these two large and remarkable craters on the Moon. Standouts in the dark, smooth lunar Sea of Fertility or Mare Fecunditatis, Messier (left) and Messier A have dimensions of 15 by 8 and 16 by 11 kilometers respectively. Their elongated shapes are explained by an extremely shallow-angle trajectory followed by the impactor, moving left to right, that gouged out the craters. The shallow impact also resulted in two bright rays of material extending along the surface to the right, beyond the picture. Intended to be viewed with red/blue glasses (red for the left eye), this striking stereo picture of the crater pair was recently created from high resolution scans of two images (AS11-42-6304, AS11-42-6305) taken during the Apollo 11 mission to the moon.

New sulfur-based battery is safer, cheaper, more powerful than lithium-ion

Scientists at the DoE’s Oak Ridge National Laboratory (ORNL) have struck the battery mother lode: They’ve created an all-solid lithium-sulfur battery that is cheaper, less flammable, and has four times the energy density of conventional lithium-ion batteries. Beyond the obvious gains from a four-fold increase in energy density, these sulfur-based batteries could play a key role in electric vehicles and airplanes, where the flammability of lithium-ion batteries is a serious concern.

We have known about the potential of lithium-sulfur batteries for decades. Theoretically, sulfur-lithium battery chemistry can have an energy density (watt-hours per gram) that is 10 times that of conventional lithium-ion batteries. In small-scale testing, sulfur-lithium has been shown to have an energy density that is four times that of lithium-ion. Another advantage is that sulfur cathode is a lot cheaper than the lithium-based cathode normally used in a lithium-ion battery. Sulfur, by virtue of being a byproduct of petroleum processing, is almost free.

The problem with conventional lithium-sulfur battery chemistry, though, is that the liquid electrolyte — which is present in just about every commercial battery chemistry — essentially burns through the sulfur cathode, resulting in a battery that’s only good for a few charge-discharge cycles. The scientists at ORNL have solved this problem in two ways: They’ve developed a new, more-rugged sulfur-based material for the cathode — and they’ve also introduced a solid electrolyte, further reducing the wear and tear on the cathode. This new cathode material, fashioned out of lithium polysulfidophosphates, has a massive capacity of 1,200 milliamp-hours (mAh) per gram after 300 charge/discharge cycles; a lithium-ion cathode, on the other hand, has a capacity of just 140-170 mAh/g.

The world’s fastest computer, Titan, is also situated at ORNL

Combined with the solid electrolyte, and after factoring in lithium-sulfur’s lower voltage, the ORNL battery has four times the energy density of the lithium-ion battery in your smartphone. In other words, if your current smartphone battery gets you eight hours of use, a lithium-sulfur battery should get you 32 hours.

Beyond its increased power density, the use of a solid electrolyte instead of flammable liquid electrolyte should significantly reduce the chance of combustion. This is good news for Boeing, which recently had its fleet of 787 Dreamliners grounded due to some on-board battery fires, and for electric vehicle makers.

Moving forward, ORNL’s new battery is still in the demonstration stage, but the team has filed for a patent. It’s easy to get bogged down by the seemingly never-ending stream of go-nowhere battery advances, but this one, by virtue of its efficacy, frugality, and relatively simple chemistry, really could come to market in the next few years. Maybe the Department of Energy’s plea for a 5x improvement in chemical batteries within five years will actually come to pass.

What ur Email says about U...............

Mantis Shrimp Amazing Beautiful

Stomatopod crustaceans (mantis shrimps) possess an incredibly complex visual system, comprised of compound eyes that contain more types of photoreceptors than in any other known animal. The mantis shrimp eye’s optical arsenal includes monocular range finding capability, 12-channel colour vision, 2 channel linear polarization detection, and, in some species, the ability to detect and analyze circularly polarized light. Underlying this unparalleled array of functional capabilities is a structural diversification of a basic photoreceptive unit common to all compound eyes the ommatidium. In the following, the mantis shrimps visual prowess is described in the context of the design variations and the distribution of its ommatidia.

Mantis Shrimps shows the eye of the scaly-tailed mantis, Lysiosquilla scabricauda. It consists of upper and lower (dorsal and ventral) hemispheres separated by a narrow central band. A close examination of the eye’s surface reveals that each region consists of closely-spaced parallel rows of facets tiny ones in the hemispheres and much larger ones in the band. The hemispheres have many rows of facets but the band has only six. Looking beneath the surface reveals that each facet is the tip of an elongate structural unit, known as an ommatidium. All ommatidia are optically sensitive devices, but those in the band are the most complex, most functional, and most interesting.

The various ommatidia share certain general structural features. In particular, each ommatidium
consists of the following three sections, from top to bottom: (i) the cornea (ii) the crystalline cone (a hexagonal converging lens), and (iii) the rhabdom (rod). The rhabdom is a transparent light sensor/guide consisting of 8 photoreceptor cells a short cell (R8) sitting atop 7 long cells (R1, R2, …, R7) that are fused along a central axis. Each cell has numerous interdigitating, coplanar, finger-like constructs (microvilli) containing light-sensitive molecules. At the bottom of each rhabdom there is a conduit (axon) that conveys electrical signals to neurons. Within the framework of these general similarities, the various ommatidia have internal structural differences that give them quite different light-sensing functionalities. These will now be described.

Each ommatidium in the hemispheres is long and thin, with a rhabdom consisting of a short R8 cell on top of a ring of R1-R7 cells. There are two sets of microvilli distributed over the 8 cells. One set consists of parallel planes of coplanar microvilli, while the other set is similarly distributed in planes that are perpendicular to those of the first set. The R8 cell has both sets, but the other R1-R7 cells have one set each. This may have significance, as discussed below.

When non-polarized sunlight enters the earth’s atmosphere it interacts with atmospheric molecules and is scattered (preferentially in the blue end of the spectrum) in all directions. When viewed at an angle of 90o to the incident beam, the scattered light appears linearly polarized, meaning that the electric vector of the light wave is along a line that is perpendicular to both the incident beam and the line of sight. The sky is therefore full of linearly polarized light. Many animal species (e.g. bees, locusts) have developed an ability to use this ambient polarization to navigate even when the sun is obscured.

 The parallel planes of coplanar microvilli is suggestive of sensitivity to linear polarization. The aligned light-sensitive molecules of the microvilli will sense linear polarization by oscillating only in response to electric vectors vibrating parallel to the molecule’s vibration axis. Perpendicular planes of microvilli should therefore detect light with perpendicular planes of polarization. In the R8 cell the presence of the two sets of perpendicular planes likely has a “null” effect a linearly polarized wave enters the cell, splits into two perpendicular components oscillating parallel to each plane, and the two components recombine on exit to regenerate the original linearly polarized ray. As if nothing had happened.

The two sets of planes thereby destroy linear polarization sensitivity (LPS). However, it is not clear what happens next in the R1-R7 cells. Since each of these cells has only one set of parallel microvillar planes, it all depends on what the the receiver of the seven independent signals does with them. It could either merge them to destroy LPS or use them to advantage. Which of these actually happens is still not known. 

The long axes of the ommatidia in the first few rows adjacent to the midband are skewed slightly
inwards relative to the optical axes of the ommatidia in the midband, which are perpendicular to the cornea. The ommatidia in the more distant rows have axes nearly parallel to the midband axes. It has been suggested that the intersections of these skewed optical axes from opposite sides of the midband, and hence intersections of the visual fields of these ommatidia, give rise to a monocular range-finding and speed-measuring capability. Experiments have shown that stomatopods have both monocular and binocular range-finding capability, the former being short-range and the latter longrange. Most of the ommatidia in the hemispheres, however, are parallel to each other as well as to the ommatidia in the midband, and therefore sample nearly the same narrow visual fields. No wonder mantis shrimps are constantly moving their eyes they have “tunnel vision”.

Why Mantis Shrimp is my new Favourite animal?????