Cosmos top snapshots of 2015

Hide and seek

Many animals use visual camouflage to blend into the background and avoid being eaten. But what about predators who hunt by smell? The harlequin filefish has an answer for that too, an Australian-led study has shown. This tropical reef fish doesn’t just look like the surrounding coral, by eating it and then exuding certain coral chemicals, it smells like it too. It’s the first example of this chemical camouflage trick ever observed in a vertebrate. 

Ice blue beauty

Alex Cornell was at the right place at the right time to catch this iceberg soon after it flipped in Cierva Cove, Antarctica. Icebergs usually appear white because they have been coated with snow. This one revealed its true nature: a glassy blue jewel. That means it probably originated from a glacier, and a very old one at that. The older the ice, the denser and more blue it appears.

Wrinkles in time

This dramatic image of faults just south of the Tien Shan mountains, in northwestern Xinjiang province, China, was the winner of NASA’s photo competition, Tournament Earth 2015.
The highest hills reach 1,200 metres and are decorated with distinctive red, green and cream-coloured sedimentary rock layers. The red layers near the top of the sequence are Devonian sandstones formed by ancient rivers. The green layers are Silurian sandstones formed in a moderately deep ocean. The cream-coloured layers are Cambrian-Ordovician limestone formed in a shallow ocean. 

Dyeing under the microscope

Biochemist-artist Linden Gledhill was staining yeast cells with food dyes when he accidentally used too much dye on one specimen, and a tiny drop crystallised on the edge of the microscope slide. Gledhill was so struck by the dye crystals’ dramatic shapes that he began to explore, systematically examining dye after dye for the type of crystals they would form. This image, captured at approximately 100 times magnification, is the crystallised remains of a drop of black food colouring, a mixture of several different dyes. 
See more of his work here: Dye crystals up close

The tree inside a silk moth

Take a deep breath: this is not some sea monster dredged up from the midnight zone. It’s a part of a silk moth caterpillar’s airway, as seen through a microscope. All insects, including caterpillars, do not have lungs. Instead, a tree-like network of tubes called trachea permeate their body. Air diffuses through the trachea to supply the insect’s cells with oxygen. This image, of a dissected section of the silk moth caterpillar’s tracheal tree, was captured by biologist turned nature photographer David Maitland. The image forms part of the UK Royal Photographic Society’s 2015 International Images for Science exhibition. 

Fire and ice

“Some say the world will end in fire, some say in ice.” Robert Frost’s lines could have been inspired by the lava field of Holuhraun, north of the Vatnajokull ice cap in the Icelandic highlands. Lava has been oozing through fissures here since 29 August, 2014. The lava field now covers more than 85 square kilometres – the largest seen in Iceland since 1783. Frost would have appreciated the desolate spectacle. His poem ends: “From what I’ve tasted of desire/I hold with those who favour fire. /But if it had to perish twice, /I think I know enough of hate /To say that for destruction ice /Is also great /And would suffice.”