A group of marine biologists have identified 7 new species of sea worm, using remote-controlled robotic submersibles that follow tiny packs of these furred, luminescent creatures. Many of these worms have a unique defense: They secrete small, glowing "bombs."
Though worms with the glowing bombs have been documented before, they are now numerous enough that researchers have classed them together as a group. All the worms studied propel themselves with long, bristly fans that serve as paddles. The "bombs" themselves form on these 18-93 milimeter-long worms' heads, and are basically tiny sacs filled with two bags of fluid. Presumably, releasing the "bomb" causes the two fluids to mix and become bioluminescent.
Write the researchers:
Green bioluminescence occurs in all the "bomb"-bearing species tested for luminosity. The luminescent structures are colloquially termed bombs because they suddenly burst into light when released by the animal, glowing intensely for many seconds then slowly diminishing. Similar autotomy of bioluminescent structures is thought to be a defensive behavior, distracting a predator while the animal escapes, and has been documented in a brittle star and a squid.