Watch the first ever footage of wild coral kissing and fighting

时间:2019-03-05 14:09:01166网络整理admin

By Sandrine Ceurstemont Tiny coral polyps have been recorded kissing for the first time, thanks to a brand new way of filming sea life. The novel microscope camera also collected footage showing other previously unseen events, including coral turf wars and the first stages of algae taking over bleached reefs. “We were definitely surprised by this interesting behaviour,” says Andrew Mullen from the Scripps Institution of Oceanography in San Diego, California. He and his colleagues left their underwater microscope to capture time-lapse images at the bottom of the Gulf of Eilat in Israel – and found the kissing video amongst the footage (see above). The corals seemed to “kiss” at regular intervals after they had captured plankton, so the team suspects that they are exchanging materials during their embrace, though no one knows yet why they do it. Andrew Mullen The team isn’t surprised to have spotted something we’ve not seen before – it’s what their instrument was designed to do. Their system is the first that can be set up on the sea floor to autonomously film millimetre-scale phenomena at high resolution, capturing video for up to 8 hours at a time. Previously, it was possible to observe tiny organisms like plankton floating in the ocean, but organisms on the seafloor would have to be brought back to the lab to be studied in detail. Designed to be deployed by a diver, the microscope uses an adjustable lens that can be focused quickly and precisely. “It works in a similar way to your eye, by changing its shape to focus,” says Mullen. The system uses a short exposure to reduce blur caused by underwater turbulence, while the lens can be positioned at a distance from an organism to avoid disrupting it and its environment. Emily L. A. Kelly As well as recording neighbouring polyps intertwining their tentacles, it also witnessed coral turf wars (see video). When colonies of different coral species were placed close together during an experiment, individual polyps extended filaments towards unrelated corals whereas they barely acknowledged those of their kind. Across the world in Maui, Hawaii, the camera captured algae colonising corals, a process that can drastically change the health and structure of a reef. At this reef, algae were rapidly spreading over recently-bleached corals that were still alive. Previously, we didn’t know how algae could grow on living corals, but the new observations – which captured the behaviour at the microscale – revealed that the algae weren’t growing on top of the coral polyps but rather in the spaces between them. Images uncovered a honeycomb structure of algae on the bleached surface. “A possible explanation for the pattern is that areas between polyps are damaged by bleaching, exposing the underlying skeleton and providing a surface for colonisation,” says Mullen. Apart from reefs, the microscope should be useful for examining a range of marine ecosystems, from sea grass beds to mangroves. The team hopes to tackle kelp forests soon. “We would like to investigate the recruitment of new kelps on bare rock, which land on its surface in a microscopic stage,” says Mullen. Stephen Jones from 4-deep, a company that has developed an underwater holographic microscope, thinks the system is invaluable for observing organisms for long periods of time in their natural environment. “It will no doubt generate valuable scientific data on coral polyps’ physiology and ecology, for example,” he says. Journal reference: Nature Communications, DOI: 10.1038/ncomms12093 More on these topics: