Spiny, starfish-like creatures called brittle stars are rapidly changing colour and shape, experimenting with different sizes, and building nets filled with razor-sharp spikes to catch fish. Some types of sea-urchins are testing out new reproductive techniques, giving birth to live young rather than dropping eggs into the freezing water. Fish, shellfish, sea stars - you name it, it's changing. A brittle star: These creatures are rapidly evolving. Credit:Museums Victoria Why all this evolution is happening remains a mystery, but the scientists suspect it may reveal evidence of a mass-extinction event that occurred millions of years ago, which life in the deep is only now recovering from. Dr Tim O’Hara, a senior curator at Museums Victoria, and a team from the CSIRO have spent the past few years taking boats out into the hairy conditions of the Southern Ocean, fishing up to four kilometres beneath the surface for some of the most extreme animals on Earth.

By way of comparison, a nuclear submarine can dive to a maximum depth of just 500 metres. They’ve found huge creatures with fishing rods for heads, zombie worms, bioluminescent sea stars, meat-eating sponges and tripod-fish, strolling through the ocean on stilt-like legs. Combining the results of those studies with genetic data and hundreds of thousands of animal-sighting records from museums around the globe has allowed them to build, for the first time, a comprehensive atlas of life in the southern oceans. With all the data collected, they decided to first look at brittle stars, a good group to examine because they are abundant on the seafloor. Dr Tim O'Hara with specimens from the museum's collection. In the jar is a brittle star. Credit:Scott McNaughton

Brittle stars look like terrifying relatives of starfish. They lack a brain or eyes, but can sense their prey in the water and swim toward it with their long, spiny arms. Some eat detritus; others use their spiked arms to catch any fish foolish enough to stray too close, pulling the fish in towards their mouths. They found brittle stars appeared to be evolving much faster in the Antarctic than anywhere else in the world. If it is true of brittle stars, it is likely true of other species. Their dramatic finding, published in the Nature journal on Thursday, suggests there has been an explosion of life in the deep waters off Antarctica, with a new species being pumped out into the world's oceans. It upends the old assumption that evolution happens much faster in the warm tropics than the cold Antarctic. A deepsea lizardfish, one of the creatures fished up by the museum's team. Credit:David Paul

“Antarctica is pumping out the species,” Dr O’Hara says. “And the tropical deep sea is more like a museum. It’s extraordinary – and not what people thought.” The museum fished out a range of monsters from the deep. This is a Sloane's Viperfish. Credit:David Paul Another Nature paper, published in July last year, found a similar polar evolutionary hotspot for fish. Most of the creatures’ evolution was happening in internal organs, adapting them to the cold temperatures with innovations such as "anti-freeze blood".

"External appearances will come later - mutations, different experiments with colour and arm size," Dr O’Hara says. Deep-ocean currents were then carrying these newly-evolved life-forms around the globe. Another deep-sea creature the museum fished up. Credit:David Paul What’s spurring this frenzy of evolution? No one knows, but Dr O’Hara suspects it may be a mass extinction event. Beginning about 33.5 million years ago, the Earth’s poles started to cool by about 15 degrees. This created the polar ice caps, and eventually killed nearly everything living in the nearby ocean.