Fish filmed spitting ostracod 'fireworks'

One of nature's most dazzling underwater displays, bioluminescence, has been captured as a form of self-defence by a BBC film crew.

Ostracods are one of the ocean-living animals which give off light when they are disturbed.

They produce the chemicals luciferin and luciferase, which emit light when mixed together. The process is called bioluminescence, an adaptation that allows animals to be seen in the complete darkness of the deep sea.

To demonstrate why organisms are able to generate light, ostracods were put into a tank containing cardinal fish, which eat plankton.

When an ostracod is swallowed, it emits a burst of light, making the cardinal fish spit it out.

Physicist and BBC presenter Helen Czerski said: "It's like a little fish firework."

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Deep-Sea Squid Can 'Jettison Arms' as Defensive Tactic

ScienceDaily (Aug. 2, 2012) — A postdoctoral researcher at the University of Rhode Island has observed a never-before-seen defensive strategy used by a small species of deep-sea squid in which the animal counter-attacks a predator and then leaves the tips of its arms attached to the predator as a distraction.

Stephanie Bush said that when the foot-long octopus squid (Octopoteuthis deletron) found deep in the northeast Pacific Ocean "jettisons its arms" in self-defense, the bioluminescent tips continue to twitch and glow, creating a diversion that enables the squid to escape from predators.

"If a predator is trying to attack them, they may dig the hooks on their arms into the predator's skin. Then the squid jets away and leaves its arm tips stuck to the predator," explained Bush. "The wriggling, bioluminescing arms might give the predator pause enough to allow the squid to get away."

The discovery was published in the July issue of the journal Marine Ecology Progress Series.

While Bush was a graduate researcher working with the Midwater Ecology Lab at the Monterey Bay Aquarium Research Institute, she observed that many octopus squid had arms of different lengths. Scientists had speculated that they may release their arms, just as lizards can release their tails when attacked, but no one had seen it happen. Using a remotely operated vehicle in the Monterey Bay Submarine Canyon off the coast of California, Bush poked at a squid with a bottlebrush.

Continued: http://www.sciencedaily.com/releases/2012/08/120802150437.htm