Science News Headlines . Are pesticides hidden danger to child IQ? . Is the hobbit just a dwarf cretin? The hobbit is a modern human affected by iodine deficiency in the womb, say Australian researchers . Sea monster had teeth like cucumbers . Airborne bugs make rain and snow . Mercury has super long, glowing tail; other planets have tails too . Snakes hear through their jaws Sea monster had teeth like cucumbers The fossil of a 15 metre long sea monster called the pliosaur has been found in Arctic Norway. It was dug up in the archipelago of Svalbard, 1300 kilometres from the north pole. Pliosaurs were the top marine predators of the Jurassic era, living in the northern seas and preying upon squid-like animals, fish and other marine reptiles. They are now extinct. The 150-million year old pliosaur lived at the time of the dinosaurs. Its lower jaw is about 3 meters long, large enough to fit a car inside, if cars had existed then. It has dagger-like teeth in a mouth large enough to bite a small car, researchers say. It is currently the biggest of its kind known to Science. The Natural History museum at the University of Oslo in Norway has recorded this find. Another type of fossil marine reptile, the ichthyosaur, was bigger, up to 23 metres in length. It is likely that the pliosaur was more fierce, though, with jagged teeth the size of cucumbers. The Norwegian museum says that it is planning to return in mid-2008 to excavate a skull and skeleton of another gigantic pliosaur recently found near The Monster. Airborne bugs make rain and snow A new study shows that biological organisms play a surprisingly large role in how rain and snow form. They are the seed around which ice forms in the atmosphere. Scientists have long known that the ice crystals in clouds that become rain or snow need to cling to some kind of particle, called ice nucleators, to form in temperatures warmer than minus 40C. But they did not realise, until now, that the most active particles involved in this process are biological ones. Mineral (or inorganic) ice nucleators are typically dust and soot. They can only capture and freeze moisture at temperatures below about minus 10C. But it was found about 40 years ago that certain plant bacteria could capture the moisture present in air and turn it into ice even at temperatures as warm as minus 2C. The resulting frost can harm or kill the plant. These bacteria were found in many places in the snow, from Europe to North America and even in the Antartica, although in different concentrations. Since there are no plants in the Antarctica this shows that they can be carried great distances by the wind. Hence they also help in spreading plant disease. This is being studied only now. The finding could help researchers improve climate forecasts. It could also help to understand the relationship between the biosphere and climate. The discovery could also one day be used to bring rain to dry areas in future. Mercury has super long, glowing tail Mercury's tail of sodium gas, seen here in the centre of the image, is 2.5 million kilometres long. The insert shows where on the planet the tail gases come from. (Source: Center for Space Physics, Boston University). The glowing dragon tail of sodium atoms is more than seven times longer than ever suspected, scientists report. It is estimated to be more than 100 times the radius of the planet itself. The neutral sodium atoms that make up the 2.5 million kilometre-long streamer are thought to be blasted off the surface by the sun and micro-meteor impacts. These impart enough energy to launch the atoms into space. These atoms stream in the solar wind like the long tail of a kite. Other elements are also in the tail. But it is the sodium that lights up and can be detected. Mercury's tail has been seen before, but scientists missed its great length as they were looking at too small a piece of the sky. Now they are using wide-angle imaging with a telescope at McDonald Observatory. With this, they can see images as wide as 16 moons (8 degree angle). This helped them to spot the sodium tail that is about 4 moons long. In the image Mercury is blocked out because its brightness outshines the sodium tail. If Mercury were shown to scale in the image, it would be less than a pixel in diameter (less than a dot on the image). To understand how Mercury's tail is created, the scientists also made close-up sodium-glow images of Mercury. This revealed that the planet has two sodium hot spots, both at high latitudes. These could be the product of the planet's mineralogy, topography or have something to do with how the planet's magnetic field channels in particles from the sun. That's similar to how Earth does the same thing and creates aurora light shows near the poles. The secrets of these hotspots are likely to be revealed by the Messenger spacecraft, which made a close fly-by of the planet in January and is scheduled to settle into orbit in March 2011. A large part of Messenger's mission will be to map out the mineral composition of the swiftly moving planet. Other planets have tails too Mercury is not the only heavenly body with a sodium tail. Neutral sodium is also seen streaming from our moon and forming a haze around Jupiter from the sodium blasted off of its tiny and hyper-volcanic moon Io. It's also seen blowing from comets. Because tails are associated with rocky bodies in our solar system, scientists believe they could some day help planet hunters identify rocky worlds orbiting other stars. Snakes hear through their jaws It is well-established that snakes neither have ears visible on the outside nor any ear-drums internally. For years it was assumed that snakes couldn't hear, and that they sensed prey by smell, taste, and in some species, special heat-sensing pits near the nose. But basic experiments during the 1970s showed snakes could hear. How can this be? Scientists have shown for the first time how snakes can hear. Snakes pick up their prey's vibrations via their jaws. They then send these patterns to their brains for processing. The US and German research shows that snakes have two hearing systems, one via their jaws. This provides valuable insight into snake evolution. With each tiny footstep, a mouse or other prey radiates waves through the ground and air the same way drops of water ripple through a pool and produce a single drip sound. Just as a ship bobs up and down in response to a wave in the ocean, a snake jaw resting on the ground responds to sound waves carried by the ground. The lower jaw of a snake is like a ridged cylinder. So in that respect it's not terribly different from a ship. Just as a ship can move in six different directions (heave, pitch, roll, etc) so can a snake's jaw (up, down, side to side, etc). In fact, the researchers used the same equations that measure a ship's movement to model how a snake's jaw would move in response to waves moving through sand or earth. And just as a ship is more stable the deeper it rides in the water, snakes often bury themselves in sand to make their hearing more precise. Buried, a snake can more easily detect the differences in the way its jaw moves. After a sound is picked up by a snake's jawbones, it travels into the cochlea, where nerves pick up the signal and transmit it to the brain. By hearing through their jaw bone and through a traditional ear, snakes essentially evolved a second way to hear, say the researchers. Humans also have a very crude version of this ability. If you hit a tuning fork lightly and place it in the air next to your ear, the sound will be faint. If you lightly hit the tuning fork again and then place the base against the bone behind your ear, the sound becomes much stronger. While a human jaw is one complete bone, snakes have two jaws, an adaptation that allows them to swallow prey larger than themselves, but also apparently lets them hear in stereo. Adapted from many news agencies