This film is about cephalopods, but does feature an exciting segment showing two different mantis shrimps. The particular segment starts out with a woman being wheeled into the emergency room of a hospital after being bitten by the most dangerous octopus around, the tiny, but extremely venomous, blue-ringed octopus. The blue-ringed is then shown stalking a dark-colored stomatopod in one of the tide pools that litter the Australian coast. The mantis shrimp, which is probably a third of the size of the mollusc, easily evades the relentless hunter, which soon comes upon much easier prey in the form of a lurking crab. The octopus subdues the crab with a quick bite from its poisoned jaws, then settles down to eat.
A second, green-hued mantis shrimp then peers tentatively out of a nearby rock formation. The stomatopod is much, much smaller than the octopus, but it immediately lunges out and drives the cephalopod from the front of the rock. The blue-ringed octopus cannot mount a direct, frontal assault because of the formidable weapons of the tiny mantis shrimp, but it goes around the rock formation and squeezes its tentacles into the crevices that tunnel into the formation. It then releases some sort of poison into the rock holes (or maybe even manages to touch the vulnerable rear of the stomatopod), because the mantis shrimp in front (who had been futilely looking around for the intruder) slowly drifts down to unconsciousness, its drooping compound eyes a testament to the efficacy of the octopus' venom.
NOTE: I guess you should never take for granted what you see in film. Although I had deduced from the appearance that there were two different mantis shrimps involved in the above, Dr. Roy Caldwell sheds more light into what actually may have happened:
That sequence was actually cut together from several shots. There are actually two different species of mantis shrimp shown and neither species occurs near Sydney where the octopus was from. I know and have worked with the person who filmed the sequence. He was trying to show behavior that has been reported previously - venom release by blue-rings to subdue prey (or potential predators at a distance, but I and others I know who work on blue-rings have been unable to elicit this behavior. It may occur, but I have not seen it).
More like what happened is that the octopus was struck several times by mantis shrimp, was damaged by the blows and leaked some TTX, and in the confines of the tank in which the sequence was being photographed, the stomatopod was killed.
Host George Page, Public Broadcasting Services/Oxford Scientific Films, 1995.
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