Hanging from the underside of an Antarctic ice floe, a sea anemone’s delicate, glassy tentacles wave in the current. This is Edwardsiella andrillae, one of the planet’s most remarkable creatures. Unlike other sea anemones that dwell on the ocean floor, this recently discovered species thrives by embedding itself in ice – though how it penetrates the floe with its soft body or survives there remains a mystery. The photograph, taken by Laurent Ballesta, is the first detailed image of the species and is one of a series that has won the portfolio award at the Wildlife Photographer of the Year competition, which will be unveiled this week at the Natural History Museum in London. “Seldom has such a jewel box of images been collected together, and all from under the ice in Antarctica,” said Roz Kidman Cox, chair of the judging panel. “The richness, variety and technical prowess of this underwater portfolio is extraordinary.” An experienced underwater photographer and biologist, Ballesta, who is based in France, spent two years planning his expedition to Antarctica. In total, he made 32 dives in temperatures around minus 1.7C – including the deepest, longest dive ever made in the Antarctic – and describes the process of diving under the ice as “like diving into a cave but with a much better chance of getting lost”. The resulting portfolio, Under Antarctic Ice, reveals the incredible diversity of life that exists in the waters there. Ballesta’s photographs include one of a possible new species of dragonfish surrounded by a wide variety of underwater life forms including creatures called brittle stars, as well as Antarcturid isopods and orange sea squirts. Taking this image was not easy, however. “It was one of the most difficult dives I have ever done,” says Ballesta, who made his descent through a small opening in the ice off Adélie Land in eastern Antarctica. After taking his photographs, he had to suffer hours of decompression in the extreme cold before he could return to the surface. In the ferociously cold waters off Antarctica many species are affected by a phenomenon known as polar gigantism, which causes invertebrates to evolve much larger bodies than related species in warmer waters. One example is illustrated by Bellesta’s photograph of a creature known as a giant Antarctic sea spider – though technically it is a pycnogonid, not a spider. Pycnogonids are widespread across the globe but are usually very small. In the Antarctic they grow to the size of dinner plates. Their internal organs develop inside their legs and they feed by sucking the juices from soft-bodied invertebrates through a long proboscis. Other dramatic looking species photographed by Ballesta include a helmet jellyfish, whose bell-shaped dome trails tentacles that are used to grasp and reel in its prey, such as krill, and which can emit blue light flashes to warn off predators. However, it was the image of Edwardsiella andrillae that provided the biologist with the most satisfying image of his portfolio. As he ascended from a deep dive, Ballesta was exhausted, freezing and desperate for a distraction from the pain he was suffering – when he came across a field of the sea anemones dangling from an ice floe like Christmas decorations. Taking their photographs provided distraction from the discomfort he was experiencing while also illustrating the wonders that can be found in the seas around Antarctica. This latter point is stressed by the wildlife photographer Jen Guyton, one of the jury members who awarded this year’s portfolio prize to Ballesta: “These photographs are a reminder that our oceans are still full of discoveries to be made and surprises to be found and that they must be protected.”