![]() The “ice dragonfish”, Cryodraco antarcticus, is a notable exception, however, and another of my favourite animals – with antifreeze proteins that stop its blood from icing up. Fish dominate as predators in most marine ecosystems today, but few fish species can cope with the -1.5☌ conditions where we were diving. ‘Ancient ocean ecosystems’ĭiving in the Antarctic is also a journey back in time, to glimpse what ancient ocean ecosystems were once like. Sea spiders lack a respiratory system, which usually limits their size, but can grow much larger in the oxygen-rich conditions here. ![]() So the Antarctic is where the world’s deep oceans breathe in – and its waters are among the most oxygen-rich on our planet.Īnother of my favourite animals from our dives takes advantage of those oxygen-rich waters: giant sea-spiders, with legspans up to 40cm across. As this deep water flows out from the Antarctic, it carries oxygen, dissolved from the atmosphere at the surface. As seawater freezes around the white continent in winter, it leaves behind very cold and salty water that sinks and flows into the depths of the Atlantic, Indian and Pacific Oceans – even the deepest water in the ocean, at the bottom of the Marianas Trench 14,000km away, came from here. Much of the life-giving oxygen in deep waters across the world begins its journey from the atmosphere here. The ocean around Antarctica is also the lungs of the deep. Some stayed behind, however, becoming the species that we saw. Her descendants then spread out across the abyss like wagon-train pioneers, giving rise to several different species of deep-sea octopus found around the world today. One of my favourite animals that we saw on dives was the octopus Graneledone antarctica, whose ancestor ventured down from the shallows around 15m years ago, when the water temperature at the surface cooled to the same chilly temperature as the deep. So although the continent itself is remote, we can reach the deep ocean close inshore here – handy for us diving in minisubmarines, despite the need to dodge icebergs. It’s also cut by even deeper channels close inshore, some plunging more than 1km, scoured out by larger ice sheets in the past. Because Antarctica is pushed down by the weight of its ice sheets, the submerged continental shelf around it is deeper than usual, around 500-600m deep at its edge rather than 100-200m deep. The deep ocean around Antarctica is a special place for several reasons. And while we didn’t face anything like the physical hardships endured by early polar explorers on land, those dives did give us the opportunity for some unique science. Thanks to the crew of the research ship Alucia, we dived in minisubmarines to 1km deep in the Antarctic for the first time. So I jumped at the chance to join a team from the BBC on an expedition to the Antarctic Peninsula for Blue Planet II, to help them as a scientific guide. Fast-forward more than a century – and the deep ocean floor around Antarctica still offers a “white space”, beyond the reach of scuba divers, only partially mapped in detail by sonar from ships and seldom surveyed by robotic vehicles. “It has always been our ambition to get inside that white space, and now we are there the space can no longer be blank,” wrote the polar explorer Captain Scott, on crossing the 80th parallel of the Antarctic continent for the first time in 1902.
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