Sea lilies caught creeping away from trouble

 作者:疏厅     |      日期:2019-04-04 05:07:08
By Will Knight (Image: Tomasz Baumiller and Charles Messing) The humble sea lily, which normally remains rooted to the ocean bed by a stem, has been caught creeping away from predators in deep sea video footage. The creature – Endoxocrinus parrae – is an ocean animal closely related to the starfish, sea cucumber and sea urchin. With a ring of feathery fingers and a stalk 50 centimetres long, it resembles an ocean garden flower. But the new video shows it has a sophisticated method for avoiding danger. The footage (600KB, requires Quicktime) was taken at a depth of 430 metres from a submersible close to Grand Bahama Island. It shows, for the first time, a sea lily crawling slowly across the ocean floor on its fingers, dragging its broken stem behind it. The video was discovered by Tomasz Baumiller of the University of Michigan and Charles Messing of Nova Southeastern University’s Oceanographic Center in Florida, both in the US, from archive footage captured over the last decade. It was presented at a meeting of the Geological Society of America on 16 October. Until the late 1980s scientists thought sea lilies could not move from place to place, unlike other species of Crinoid, such as the feather star. But Baumiller has previously shown that the sea lily can shed part of its stem in order to relocate. Other footage and photographs captured by Baumiller and Messing now suggest the sea lily makes its ocean floor dash to escape the attentions of sea urchins, which have been seen lurking on the sea bed behind the travelling sea lilies – they are known to nibble on sea lily appendages. “It’s the lizard’s tail strategy,” Baumiller says. “The sea lily just leaves the stalk end behind. The sea urchin is preoccupied going after that, and the sea lily crawls away.” Baumiller adds that the sea lilies can travel at a surprising speed, peaking at 3 to 4 centimetres per second – hundreds of times more quickly than previously thought possible. “In a race with a sea urchin, the sea lily would probably win,” he says. More on these topics: