Animals, including humans, feel sound as well as hear it, and some of the most meaningful communication happens at frequencies (频率) that people can’t hear. Elephants, for example, use these low-frequency sounds to, among other things, find family or a mate across long distances. Whales do it, too.
But you don’t have to weigh a ton to make a sound. In fact, you don’t have to be bigger than a pea. Consider, for example, the tree-hopper, a curious little animal that lives on the stems (茎) of the leaves. University of Missouri biologist Rex Cocroft has spent much of his time listening closely to tree-hoppers with his team.
The team discovers that all the sounds being heard from tree-hoppers are produced by males. They do it by vibrating (振动) their abdomens (腹部) to make a wide variety of strange sounds. There is almost no airborne sound produced with these vibrational sounds. Cocroft explained, “If a tree-hopper were to stand on your finger and produce a sound, you would feel the vibration but hear no sound.”
They showed that some sounds, not surprisingly, seem to be aimed at attracting females. And some are aimed at other males.
Cocroft explained, “When two males meet each other, or when they are mate-searching on a branch, we’re hearing ‘purring, bdddddrrrr…’ sounds that males give.” Normally, a person couldn’t hear any of this, because the sound travels along the stem, inside it. And that’s how other tree-hoppers detect it.
Cocroft said tree-hoppers have very sensitive legs. And they stand around on stems, which are good at spreading vibrations. So they just use what nature gives them to communicate with each other.
“They have so many different forms of social behavior and grouping,” Cocroft explained. “And once there are animals living in groups, then there will be all sorts of interesting possibilities for communication.”
12. What does Cocroft’s research focus on about tree-hoppers?
A.Their variety. | B.Their communication. |
C.Their living areas. | D.Their numbers. |
13. What can we know about tree-hoppers?
A.They sense sounds by legs. |
B.They knock the stems to make sounds. |
C.Their sounds can be easily heard by humans. |
D.Females make sounds to meet each other |
14. What does Cocroft say about animals’ living in groups?
A.It is key to their survival. |
B.It drives an increase in their numbers. |
C.It often leads to communication. |
D.It contributes much to the division of animal types. |
15. What is the best title for the text?
A.A Magic Moment in Nature | B.A Journey to the Wildlife |
C.Learning From Nature | D.Communication Sounds Among Animals |