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Category: Top Posts
An Icy Critter Cocktail Helped Baleen Whales Evolve
One way to understand how the ecosystem of the Antarctic originated is to look at its very base: tiny organisms called dinoflagellates, the little creatures that attract bigger creatures, and thus in effect support all of life in the ocean. Dinoflagellates produce hard cysts that fossilize well, and researcher Sander Houben and his team recently published findings in Science indicating that, once Antarctic ice began to spread over what was formerly a lushly forested, warm sub-tropical continent, the makeup of the ocean’s dinoflagellate population dramatically changed.
The Antarctic ice sheet began spreading to inland Antarctica about 34 million years ago, during a climactic shift caused by a decrease in atmospheric carbon dioxide that was cooling the planet, known as the Eocone-Oglicene extinction event. The Antarctic ice sheet is one of two polar ice caps on Earth, and covers 98% of the Antarctic continent, making it the largest single ice mass on Earth. Put another way, that’s 61% of all fresh water on Earth, held in the ice cap.
Life Could Have Evolved in Frigid Underwater Ice Gardens
New evidence indicates that chemical gardens which form beneath the Antarctic ice could be the origin of coldwater life.
Brinicles, first captured forming on film by the BBC in 2011, are hollow tubes of ice that descend from Antarctic sea ice. They look a lot like icicles, but aren’t. As sea water freezes into ice, it excludes salt and other ions, which get trapped in brine-rich compartments in sea ice. Brine has a lower freezing temperature than water, so if the sea ice cracks, the liquid is released, and immediately freezes any seawater that it comes in contact with, creating a hollow tube of ice descending into the water.
Menagerie of Animals Launched Into Space
Last Friday, a crew of geckoes, forty-five mice, eight Mongolian gerbils, fish, snails, and plant seedlings were rocket launched on the Bion M1 into space, for the longest animal space experiment to date, a round trip lasting thirty days. The Russian spacecraft will relay information to scientists on the ground interested in studying the health effects of space on the animals.
Animals were the pioneers for manned space flight. Scientists wanted to make sure animals could survive before they sent any humans. Russia sent dogs, rabbits, and mice on short duration flights in the early 1960s.
I Can See Clearly Now, the Brain is Gone
It’s been a big month for developments in transparency.
First: the Antarctic icefish, whose native habitat is 3,200 feet deep in the waters off the coast of Antarctica. Earlier this month, Tokyo Sea Life Park debuted its display of the only captive icefish in the world, prompting a flurry of news pieces about the fishes’ mysterious clear blood. The aquarium boasts they now have a mating pair of icefish, which could enable studies on their unique cardiovascular system in a controlled environment.
What makes the icefish so remarkable is that it defies yet another one of those rules of biology that seem to always have exceptions. In this case, it’s the rule that all vertebrates were thought to have red blood. This is because of hemoglobin, an iron-containing oxygen transport protein in the red blood cells of vertebrates. It carries oxygen from respiration organs like lungs or gills to all the tissues of the body, where it releases the oxygen to help power the tissues of the organism. Hemoglobin also collects the carbon dioxide produced from the activity of tissues and carries it back to the respiratory organs to be exhaled, and expelled from the body as waste.
Saturn Gets Drenched by Its Eroding Rings
Ethereal, stately Saturn, it turns out, deals with a problem we Earthlings are quite familiar with this time of year: rain. The planet gets an Olympic-pool sized quantity of water dumped on her each day.
Studying satellite images taken at the Keck Observatory in Hawaii, James O’Donoghue, a postgraduate researcher at the University of Leicester, and his colleagues noticed several mysterious dark bands on the surface of Saturn. They found that the bands correlate directly to magnetic lines that link the planet with her densest, wateriest, and most brilliant, rings, and shared these cosmic findings in a letter to Nature last week. The drizzle coming from her rings effectively douses the glowing hydrogen molecules we see on Saturn’s surface.
Saturn is famous, among humans, for her very photographic rings. But their origins, and evolution, have remained a mystery. How exactly were the rings formed to begin with? Are the rings we see today remnants of a previously more massive ring system? These recent observations indicate than an electromagnetic erosion force pulls charged water molecules from the rings and deposits them in Saturn’s upper atmosphere, called an ionosphere. Perhaps this process is playing a part in shaping the rings over time.
The rings, which look like marvelous elliptical beams of light as seen in satellite images, are actually bands of collisional, self-gravitating water-ice sludge rocks, some of which are submicrometer-sized, and others the size of mini-moonlets a few kilometers across. All these watery ice objects behave like a dense gas together, orbiting Saturn in a thin disk.
Saturn behaves like a big magnet, with magnetic field lines that link her rings to her body. Remember that iron-filing experiment in school? It’s like that. The ionosphere of Saturn’s rings is “seen” by the magnet that is Saturn, says O’Donoghue, “and effectively bounces back and forth from ring-to-planet. Some of these bouncing water particles go too far and never come back.”
There’s not much danger of the moonlets in the rings going anywhere, but the small particles in the orbiting disks behave differently when they acquire a significant electrical charge. When the sun charges the water molecules, they become vulnerable to getting swept down towards the planet’s upper atmosphere along the magnetic field lines.
The researchers estimate that about 30-40% of Saturn’s upper atmosphere is flooded regularly, the equivalent of between 1 and 10 Olympic-sized swimming pools a day. It may be, then, that these magnetic field lines are responsible for shaping the spacing and composition of the rings.
Thanks to James O’Donoghue for kindly answering my questions and consulting on images.
A fun video about how Earth’s magnetic field interacts with the Sun’s to create aurorae:
Peering Into Trilobite Eyes to See the Evolution of Vision
They might not seem like the most expressive eyes you’ve ever seen—but the beady eyes of extinct trilobites have a lot to say. Recently, they’ve given us some new insights into the evolution of vision.
Trilobites are one of the first animals in the fossil record to develop complex eyes (as opposed to the light-sensitive spots that passed as early eyes). So understanding trilobite vision is also understanding the origins of eyes themselves. It has even been hypothesized that trilobite vision drove rapid changes in their prey’s body structure as prey evolved to escape sighted predators, thus fueling the Cambrian Explosion.
Rocket Engines Recovered From Their Watery Graves
Jeff Bezos, founder of Amazon, is on a mission to retrieve the Saturn V rocket stages and engines from a watery “sculpture garden,” as he calls it, at the bottom of the sea off the coast of Florida. In a blog post on March 20th he announced that the endeavor to bring some of the F1 engines from Saturn up to the surface has been successful.
The size of small office buildings, the Saturn V moon rockets are the most powerful rockets ever to have flown. When tested, their engines shattered the windows of nearby houses. To date, the Saturn Vs are the only launch vehicles to have transported human beings beyond the low Earth orbit.
Dark Life Beneath the Ocean’s Crust
A few years back, scientists discovered that the ocean crust, previously considered a thick layer of lifeless rock that covers 60% of the Earth’s surface, actually contained some microbes. But the extent of the microbial ecosystem in the crust was unclear until a study published recently revealed that the “dark biosphere” in the ocean crust might be one of the biggest ecosystems on the planet. As creatures of the light we may find this hard to imagine, but evidently much of our biosphere is in the dark.
It’s an ecosystem based on chemosynthesis, not photosynthesis, which is the process of producing energy in the absence of light—as well as, sometimes, the absence of oxygen. This dark biosphere is the first major ecosystem on Earth based on chemosynthesis.
Plants Have Slow Sex in Space
A new study on plant reproduction finds that developing cells are very affected by altered states of gravity—a finding that has implications for our hopes for a future human society in space.
In order for plants to have sex, a pollen grain first lands on a stigma (the female part of a flowering plant.) Following a chemical come-hither signal from the stigma, the pollen grain grows a pollen tube, a tunnel for sperm cells to travel down to reach the egg for fertilization. Pollen tubes are the fastest growing cells in the plant kingdom. The pollen tube was used as a model system for a recent study on the effects of altered gravity on plant reproduction because a response in the pollen tube takes a matter of mere seconds.
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Some Plants Are Sugar Junkies
A plant’s sap is responsible for transporting sugars from the site of their manufacture (the leaves) to growth centers (further up the branch or trunk of the plant). And the system has to strike a delicate balance: if the sap has a low concentration of sugars, there isn’t much energy flowing to the plant; if, on the other hand, there are lots of sugars in the sap it becomes too thick to pump efficiently. It’s a situation a lot like transporting any payload through a traffic artery, be that a paved highway or a canal with kayakers. So what’s in a plant’s best interest?
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