One of the first green bombers (Swima bombivinidis) collected from Monterey Bay. Several green bombs are visible near the animal's head. (S.H.D. Haddock)

Scientists have discovered a group of deep sea worms dubbed "green bombers" capable of casting off appendages that glow a brilliant green once detached from their bodies — a tactic the worms could use to confuse attackers.

A number of deep sea creatures, including some deep-sea worms, have parts that glow with bioluminescence, but releasing glowing appendages when attacked is a behaviour previously seen only in a brittle star and a squid.

"They have a very strange way of using bioluminescence," said Karen Osborn of the Scripps Institution of Oceanography at the University of California, San Diego, the lead researcher of a paper in Friday's edition of the journal Science.

The seven species of worms, discovered off the coast of the Philippines and and west coast of the United States and Mexico, live between 1,860 and 3,790 metres below sea level, with four living close to the sea floor and the other three as far as 440 metres above the sea floor. They ranged in length from 18 to 93 millimetres and propelled themselves with fans of long bristles that form swimming paddles.

The "bombs" themselves are structures that burst into light when released by the animal, glowing intensely for several seconds before dimming.

"They drop one or two at a time, and if you keep harassing them they will keep dropping them," said Osborn, adding the worms are able to regenerate the balloon-like structures.

The first of these worms was given the scientific name Swima bombiviridis.

The researchers say the discovery of such a large group of previously undocumented animals is another reminder of how little scientists know about the life in deep sea environments.

With files from The Associated Press