Many bird and reptile species use hissing as a threat device against potential predators. The way these species produ...

SamA on October 14, 2019

Hello @ali,

We are given that birds and reptiles make a similar hissing sound as a defense from predators. This behavior likely developed from a common ancestor. However, the predators that existed during the ancestor's time period could not hear hissing sounds.

The question presents us with the following problem. How can hissing possibly be a defense against a predator that cannot hear? This leads me to question the passage's claims about the origin of this behavior. We need an answer choice that resolves my doubts about these claims.

C is the correct answer, because it demonstrates how hissing was an effective form of defense for this common ancestor. Even though these predators could not hear, producing the hiss caused the ancestor to appear larger, possibly scaring off its attacker.

ali on October 15, 2019

I got it now!