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  • A male firefly glows above a field on a summer's night, emitting a series of enticing flashes.

  • He hopes a nearby female will respond with her own lightshow and mate with him.

  • Sadly for this male, it won't turn out quite the way he plans.

  • A female from a different species mimics his pulsing patterns: by tricking the male with her promise of partnership.

  • She lures him inand turns him into an easy meal.

  • He's been deceived.

  • Behavioral biologists have identified three defining hallmarks of deception by non-human animals:

  • it must mislead the receiver, the deceiver must benefit, and it can't simply be an accident.

  • In this case we know that the predatory firefly's signal isn't an accident because she flexibly adjusts her flash pattern to match males of different species.

  • Based on this definition, where is animal deception seen in nature?

  • Camouflage is a good starting pointand one of the most familiar examples of animal trickery.

  • The leaf-tailed gecko and the octopus fool viewers by blending into the surfaces on which they rest.

  • Other animals use mimicry to protect themselves.

  • Harmless scarlet kingsnakes have evolved red, yellow, and black patterns resembling those of the venomous eastern coral snake to benefit from the protective warnings these markings convey.

  • Even some plants use mimicry:

  • there are orchids that look and smell like female wasps to attract hapless males, who end up pollinating the plant.

  • Some of these animals benefit by having fixed characteristics that are evolutionary suited to their environments.

  • But in other cases, the deceiver seems to anticipate the reactions of other animals and to adjust its behavior accordingly.

  • Sensing a threat, the octopus will rapidly change its colors to match its surroundings.

  • Dwarf chameleons color-match their environments more closely when they see a bird predator rather than a snakebirds, after all, have better color vision.

  • One of the more fascinating examples of animal deception comes from the fork-tailed drongo.

  • This bird sits atop tall trees in the Kalahari Desert, surveying the landscape for predators and calling when it senses a threat.

  • That sends meerkats, pied babblers, and others dashing for cover.

  • But the drongo will also sound a false alarm when those other species have captured prey.

  • As the meerkats and babblers flee, the drongo swoops down to steal their catches.

  • This tactic works about half the timeand it provides drongos with much of their food.

  • There are fewer solid cases of animals using signals to trick members of their own species, but that happens too.

  • Consider the mantis shrimp.

  • Like other crustaceans, it molts as it grows, which leaves its soft body vulnerable to attack.

  • But it's still driven to protect its home against rivals.

  • So it has become a masterful bluffer.

  • Despite being fragile, a newly molted shrimp is actually more likely to threaten intruders, spreading the large limbs it usually uses to strike or stab its opponents.

  • And that works!

  • Bluffers are more likely to keep their homes than non-bluffers.

  • In its softened condition, a mantis shrimp couldn't withstand a fightwhich is why we can be confident that its behavior is a bluff.

  • Biologists have even noticed that its bluffs are tactical:

  • newly molted mantis shrimp are more likely to bluff against smaller rivals, who are especially likely to be driven away.

  • It would seem that instead of just threatening reflexively, the mantis shrimp is swiftly gauging the situation and predicting others' behavior, to get the best result.

  • So we know that animals can deceive, but do they do so with intent?

  • That's a difficult question, and many scientists think we'll never be able to answer it.

  • We can't observe animals' internal thoughts.

  • But we don't need to know what an animal is thinking in order to detect deception.

  • By watching behavior and its outcomes, we learn that animals manipulate predators, prey, and rivals.

  • And that their capacity for deception can be surprisingly complex.

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B2 US TED-Ed deception shrimp mantis behavior female

Can animals be deceptive? - Eldridge Adams

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    陳叔華 posted on 2019/01/10
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