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A photo montage of a Marcgravia evenia flower, with its nectaries below and dish-shaped leaf above, along with a Glossophaga soricina bat (image courtesy of Ralph Mangelsdorff and Ralph Simon)

Flowers have evolved many strategies for attracting pollinators—bright colors, guiding patterns, interesting scents, brilliant mimicry. The Cuban rainforest vine Marcgravia evenia has a different strategy, though. Scientists have found that the vine has one or two specially shaped leaves hanging near its flowers that act as a bat signal, luring these flying mammals. The bats get a meal, and the flowers get pollinated. (The study appears in this week’s Science.)

The leaves have a concave shape, somewhat like a dish reflector. When researchers sent a sonar signal towards such a leaf, they found that they received back strong echoes that a bat would find easy to identify. The scientists then trained nectar-feeding Glossophaga soricina bats to find a small feeder among foliage; when they placed a replica of the special leaf near the feeder, the bats were able to find it twice as fast.

Having such a leaf does have a downside for the plant—it isn’t as well-suited for photosynthesis as more traditional leaves on the vine and thus creates less energy for the plant. But the scientists argue in their paper that “these costs are outweighed by the benefits of more efficient pollinator attraction.” In other words, the plant’s need for sex is greater than its need for more food.

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One of the most dangerous jobs in science has to be a volcanologist. When you watch the video above you can see why (although trying to get that close to a bubbling cauldron of lava is not just dangerous; it’s stupid enough that even your fellow volcanologists will yell at you). But collecting and analyzing samples of lava and deadly gases are just a couple tools in the volcanologist’s box; here are some of the other—safer—ways they study volcanoes:

Measure seismic activity: Earthquakes are an early warning sign that something is going on underground with a volcano. The rumblings can be difficult to interpret, but an increase in activity often presages an eruption.

Measure ground movements: Scientists often set up sensitive tiltmeters that can detect the tiniest changes in the shape of a volcano’s surface. Before an eruption, the volcano may start to bulge as magma accumulates closer to the surface. Before Mount St. Helens erupted in 1980, the north side of the volcano visible bulged, but more often this deformation is detectable only with sophisticated equipment.

Take the volcano’s temperature: If a volcanologist wants to see how hot a volcano has become and which lava flows are newer (and hotter), there’s no need to get up close. A thermal imaging camera on an airplane or satellite can take a picture and identify the hot spots.

Check on its geophysical properties: Minute changes in the electrical conductivity, magnetic field and even gravity around a volcano can indicate that something is brewing beneath the surface.

Map it in three dimensions: A 3-D map of all the nooks and crannies on the surface of a volcano can help scientists make predictions about where the lava will flow and who is most in danger in the event of an eruption.

Study the volcano’s past: Scientists examine geologic deposits to learn about past eruptions, which can give important clues to what a volcano may do in the future.

(HT: Bad Astronomy)

What do you hate most about mosquitoes? (photo courtesy of flickr user Aesum (Very Busy))

If there’s one downside to living in a city built on a swamp (not really—it just feels that way during D.C.’s muggy summers), it’s the mosquitoes. They hover just outside my front door, ready to take a bite from my face or, worse, follow me indoors where they can munch on me in my sleep. And then yesterday I read about how the West Nile Virus has been identified in samples of D.C. mosquitoes, which adds a layer of worry on top of the itching. After reading up on these pesky summer companions, I thought I’d share these 14 facts:

1 ) There are around 3,500 species of mosquitoes, but only a couple hundred feast on human blood.

2 ) If you’ve been bitten by a mosquito, it was a female. Male mosquitoes make do just fine with plants, but females need a blood meal before they can lay eggs.

3 ) The female’s saliva contains an anti-coagulant that lets her more easily suck up her meal. The saliva induces an allergic response from her victim’s immune system; that’s why your skin gets an itchy bump.

4 ) Females lay their eggs in shallow water or even damp soil that’s prone to flooding. Get rid of any standing water near your home to reduce the mosquito horde.

5 ) The best time to avoid mosquitoes is in the afternoon, when temperatures are hottest and the insects rest in cooler spots.

6 ) The Centers for Disease Control and Prevention lists only four chemicals as being effective for repelling mosquitoes: DEET, Picaridin, Oil of Lemon Eucalyptus (or its synthetic version, called PMD) and IR3535.

7 ) Mosquitoes are attracted to the carbon dioxide, lactic acid and octenol found in our breath and sweat, and they also sense the heat and humidity that surrounds our bodies. They may also have a preference for beer drinkers.

8 ) Some scientists think that eliminating mosquitoes wouldn’t be such a bad thing. Others aren’t so sure, though, and worry about the effects on the ecosystem of the loss of an insect that is eaten by spiders, salamanders, frogs, fish and other insects.

9 ) Malaria infects around 250 million people each year worldwide and kills about one million, mostly children in Africa. About a fifth of those deaths can be attributed to counterfeit anti-malarial drugs.

10 ) George and Martha Washington both suffered from malaria. George contracted the disease when he was a teenager. In the second year of his presidency, he experienced severe hearing loss due to quinine toxicity.

11 ) Insecticide-treated nets (ITNs) that hang over a bed have been shown to reduce malaria incidence among children and pregnant women by up to 50 percent. The nets last only a few years before they have to be replaced.

12 ) The last time there was an outbreak of yellow fever, another mosquito-borne illness, in the United States was in 1905 in New Orleans. At the time, the city was trying to prevent the disease by fumigating all the ships that entered the city. However, a smuggler’s ship full of bananas avoided the quarantine and by June cases began to emerge among Italian immigrants who unloaded banana boats.

13 ) Birds were originally blamed for the spread of the West Nile Virus across the United States. But a 2010 study says that it was the mosquitoes themselves, which can travel up to 2.5 miles per day, that were responsible for the spread of the disease from 2001 to 2004.

14 ) The emergence of a worldwide outbreak of the mosquito-borne disease chikungunya can be traced to a 2004 drought in Kenya. The disease hasn’t made it to the United States yet, but scientists think that could occur at any time.

In these two images from the Hubble Space Telescope, Pluto's new moon, P4, can be seen to move around the dwarf planet (Credit: NASA, ESA, and M. Showalter (SETI Institute))

Pluto has a fourth moon, scientists announced last week. They used images from the Hubble Space Telescope to find P4, the smallest of Pluto’s satellites, estimated to be between only 8 and 21 miles in diameter. It orbits between Nix and Hydra, which circle Pluto on the outside of Charon’s path.

P4, however, is just a temporary name for the new moon. And while there are many suggestions for a permanent name, I can say that it definitely won’t be Mickey, Donald or Goofy. That’s because there are strict naming conventions for astronomical bodies. When it comes to our solar system, we’re stuck with Greek mythology and each planet (or dwarf planet, as in this case) has its own set of stories to choose names from. Let’s look at the Pluto system:

Pluto: The dwarf planet—discovered on January 23, 1930 in Flagstaff, Arizona—is named for Pluto, the Greek god of the underworld. Perhaps better known as Hades, Pluto had two brothers, Zeus, ruler of the skies, and Poseidon, who held dominion over the seas. Pluto abducted his niece Persephone to be his wife and queen. But when Persephone went missing, her mother, Demeter, goddess of the harvest, became overcome with grief; the seasons ended and everything began to die. Zeus sent a messenger to retrieve to Persephone, but because she had eaten pomegranate seeds, she remained bound to Pluto for several months every year. Her yearly return to her mother brings the spring season.

Charon: Pluto’s largest moon was discovered in 1978 when astronomer Jim Christy, examining photographic plates with Pluto’s image, noticed an odd, periodic bulge. Charon, in mythology, was the ferryman who carried souls to the underworld. (The choice of Charon as the moon’s name, however, wasn’t entirely due to its connection to Pluto in mythology; Christy wanted to name the moon in honor of his wife, Charlene, and Charon was as close as he could get.)

Nix: One of two moons discovered in 2005 with Hubble images, Nix named for Nyx, the goddess of the night and Charon’s mother. (Nix is the Egyptian spelling; Nyx was already the name of an asteroid.) Nyx lived in Tartarus, the dungeon of the underworld, and in some stories she is said to be involved with dark doings, such as protecting spies during the Trojan War.

Hydra: The other of the two moons discovered in 2005, Hydra is named for a many-headed, serpent-like beast of ancient times. If one head was cut off, two grew in its place. The hydra guarded an entrance to the underworld near the city of Argos. Heracles (a.k.a. Hercules) slew the hydra in the second of his Twelve Labors.

Mark Showalter of SETI, the discoverer of P4, has said that the name of Cerberus comes up most often in discussions of potential names for the new moon. Cerberus would certainly fit in with the mythology of the Pluto system—he was the three-headed dog that guarded the gates to the underworld. The spelling of the name would have to be altered, though, as, like Nyx, Cerberus is already the name of an asteroid.

But are there other characters that would fit in? Major characters, such as Persephone, would be inappropriate for a moon so tiny, but there are plenty of options. Here are a few of my favorites:

Erberus: Husband (and brother—ew) to Nyx and father of Charon, he personified darkness.

Styx: The river that was the border between the living world and the underworld.

Hypnos: One of Nyx’s many sons, Hypnos was the personification of sleep. His twin brother was Thanatos, the personification of death.

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A hexagonal grain of iron sulfide in a diamond may be a flaw for jewelers, but it's useful data for scientists (Credit: Jeffrey Harris, University of Glasgow)

When it comes to diamonds in jewelry, perfection is everything. But tiny little inclusions–imperfections in the crystal structure–are a clue to the past. In a study published last week in Science, scientists have now analyzed more than 4,000 inclusions found in diamonds to determine just when plate tectonics began.

As you probably know, the Earth is covered with tectonic plates that grow and move and dive under and crash into each other, creating and destroying continents and oceans over billions of years. Scientists call this the Wilson Cycle, but just when it began has been a mystery.

Diamonds are created in the Earth’s mantle, the hot and viscous layer between the core and the crust. Volcanic eruptions then bring them to the surface. There are two types of inclusion in diamonds: Peridotitic inclusions come from the melting of the mantle, which has happened continuously through Earth’s history. Eclogitic inclusions derive from shallow, partial melting that most often occurs during the formation of oceanic crust.

The scientists used two types of isotopic dating to determine when each of the diamonds in the study formed. They found that diamonds with peridotitic inclusions formed before 3.2 billion years ago, and after 3 billion years ago, eclogitic inclusions were far more common. The researchers concluded that the cycle of plate tectonics must have started around 3 billion years ago.

“The simplest explanation” for the emergence of eclogitic inclusions as the dominant type, says the study’s lead author, Steven Shirey of the Carnegie Institution of Washington, is that this change came from the initial subduction of one tectonic plate under the deep mantle keel of another as continents began to collide on a scale similar to that of the supercontinent cycle today.”