A STORM ON SATURN isn’t doing things by halves – it has been churning for months through the atmosphere of the ringed planet, and Nasa’s Cassini spacecraft has captured images. Scientists registered the storm last December as a prominent white spot in the northern hemisphere. Since then it has circled the planet, covering approximately 4bn sq km.
Two papers in the journal Nature last week describe features of the storm, which is reported to have reached a width of about 10,000km within weeks of the spot appearing.
Nor is the estimated lightning flash rate for the faint of heart, with recorded rates peaking at more than 10 flashes per second.
“This storm is the largest, most intense storm observed on Saturn by Nasa’s Voyager or Cassini spacecraft. It is still active today,” states Nasa’s website.
“The storm is a prodigious source of radio noise, which comes from lightning deep in the planet’s atmosphere. The lightning is produced in the water clouds, where falling rain and hail generate electricity. The mystery is why Saturn stores energy for decades and releases it all at once. This behaviour is unlike that at Jupiter and Earth, which have numerous storms going on at all times.”
Georg Fischer, lead author on one of the Nature papers, is quoted on the site: “Tracking a storm so different from the others has put us at the edge of our seats.”
– Claire O’Connell
How some snails survive passage to the other side
NOW HERE’S A journey: a species of land-snail can survive being scoffed by a bird, and can come out the other end intact.
The eloquently titled study, Snails Can Survive Passage through a Bird’s Digestive System, in the Journal of Biogeography proposes that being eaten by birds could offer the tiny land snail Tornatellides boeningi a means of dispersal.
Researchers at Tohoku University in Japan fed T boeningi snails to predatory birds from the Ogasawara Islands in the western Pacific – three Japanese white-eyes and one brown-eared bulbul.
The snails came out around 30-40 minutes later, and the researchers left them on wet filter paper for 12 hours – if the snails hadn’t moved by then, they were considered dead. In each case, about 15 per cent of the snails passed through the bird’s gut alive – and one snail even gave birth to juveniles after it emerged.
The researchers reckon that the small size of the T boeningi snail is an important factor in surviving the trip – the shells of larger snail species found in the bird faeces were damaged.
A genetic study of snails in the area seems to support the idea that the birds help the tiny land snails spread.
“Bird predation appears to be a method of dispersal for T boeningi, and our results suggest that bird-mediated dispersal plays a role in land snail population structure,” conclude the authors.
– Claire O’Connell