A group of glowing worms has been found dwelling in the deep ocean, some of which release body parts as tiny “bombs” to ward off predators.
Researchers describe the bizarre “Swima worms” in Science journal.
The creatures, which the scientists say could be widespread in the deep sea, indicate the extent of biodiversity yet to be discovered in the oceans.
The team found them whilst exploring the waters just above the sea-bed off the west coast of the US.
Lead author Karen Osborn, from the University of California San Diego, told BBC News that she and her colleagues found the worms accidentally, whilst exploring the deep oceans with remotely operated submersible vehicles.
“We came across them and thought they were very interesting, firstly because of their bioluminescence,” she said.
“When we brought them up and realised they were different from anything that had been described before, we became even more interested.”
Dr Osborn and her colleagues were exploring depths of up to 3,700m when they spotted the creatures.
As they continued to bring more of the worms back to their lab, they realised they had found a group of previously unknown animals.
Each of the seven species found so far is transparent apart its gut, and all of the worms produce colourful bioluminescence.
The researchers are now investigating what chemicals the animals produce to give rise to their striking glow.
The animals are also excellent swimmers – using fans of long bristles that form swimming paddles.