Multiple choice

Red ants have evolved a sophisticated defense mechanisms against various predators that raid their colonies. For example, worker ants detect a raiding ant from a rival colony at the entrance to their colony, the worker ants release warning signals which cause other ants to swarm around and sting the intruder. This makes it difficult to understand why when a swallow, which sometimes eats red ants, is detected just at the entrance to colony, no swarm-inducing signal is produced.

Which of the following, if true, contributes most to an explanation of the behavior of red ants as it is described above?

  1. A raiding ant must be stung many times by red ants before it die

  2. Swallows do not eat many ants in quick succession and never enter the colony

  3. A raiding ant must be stung fewer times than a swallow before it dies

  4. Swallows fly away as soon as it detects swarm inducing signal

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This issue to be resolved is why red ants swarm around raiding ants but not around swallows that get near the colony. We're told that the swarming around raiding ants is an example of a defense against raids on colony, so a good explanation of the ants' failure to swarm around swallow would be that the swallows are not raiding the colonies, merely coming close to them and picking off a few stray ants. Choice (2) provides this explanation.

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