Monday Science Links

This week's sciency goodness:

• Ed Yong at Not Exactly Rocket Science blogs on how nocturnal mammals see in the dark: Nocturnal animals face an obvious challenge: collecting enough light to see clearly in the dark. We know about many of their tricks. They have bigger eyes and wider pupils. They have a reflective layer behind their retina called the tapetum, which reflects any light that passes through back onto it. Their retinas are loaded with rod cells, which are more light-sensitive than the cone cells that allow for colour vision. But they also have another, far less obvious adaptation - their rod cells pack their DNA in a special way that turns the nucleus of each cell into a light-collecting lens. Their unconventional distribution is shared by the rods of nocturnal mammals from mice to cats. But it's completely opposite to the usual genome packaging in the rods of day-living animals like primates, pigs and squirrels, and indeed, in almost all other eukaryotic cells.


• Phil at Bad Astronomy celebrates Hubble's 19th anniversary: On April 20, 1990, the Space Shuttle Discovery roared into orbit, carrying with it the most famous observatory of all time: the Hubble Space Telescope. To commemorate this 19th anniversary, the Hubble folks have released this wonderful image of interacting galaxies called Arp 194. There’s quite a bit going on here! First, take a look at the upper spiral galaxy, located 600 million light years from Earth. If you look at the top spiral arm, you’ll see another galaxy nucleus lying along it; it’s the bright orange patch above and to the right of the big spiral’s center. It looks like that’s the remains of a galaxy that is in the process of colliding with the big spiral (the other bright galaxy — the compact spiral directly to the right of the big spiral’s center — appears to be a background galaxy, coincidentally seen nearby).


• Back at Not Exactly Rocket Science, Ed tells us about a beautiful transitional species, the walking seal: Seals and sea-lions gracefully careen through today's oceans with the help of legs that have become wide, flat flippers. But it was not always this way. Seals evolved from carnivorous ancestors that walked on land with sturdy legs; only later did these evolve into the flippers that the family is known for. Now, a beautifully new fossil called Puijila illustrates just what such early steps in seal evolution looked like. With four legs and a long tail, it must have resembled a large otter but it was, in fact, a walking seal. Natalia Rybczynski unearthed the new animal at Devon Island, Canada and worked out that it must have swam through the waters of the Arctic circle around 20-24 million years ago. She named it Puijila darwini after an Inuit word referring to a young seal, and some obscure biologist. The skeleton has been beautifully preserved, with over 65% of the animal intact, including its limbs and most of its skull.


• David at Irregular Webcomic! talks about Isaac Newton and Edmond Halley: It was only at Halley's insistence, and ongoing cajoling in the face of repeated attempts to abandon the project, that Newton eventually published what would become perhaps the most important book ever in the entire history of science: The Principia Mathematica. Not only did Halley make sure Newton didn't give up on this project, he paid for the publication out of his own pocket. A world today without Edmond Halley would have been almost the same as a world without Isaac Newton. Only leaving out Halley would have taken away a lot of other stuff too.


• And, on a lighter note, Jessisca from Magma Cum Laude tells us what geologists wear in the field: In the field, "geologists wear gray and khaki." And it's true, as you can see by the lovely photo of my foot in Guatemala. (There are very few photos of me because I wasn't exactly photogenic after the whole food poisoning and not eating for three days episode.) There have been a few field gear posts going around recently, and I thought I'd contribute a few photos of myself in full field attire.
  

Enjoy!