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 What's Inside A Rattlesnake's Tail?
작성자
 이** (jean)
글내용

 

Description:

If you look inside a rattlesnake rattle, you’ll find it’s actually hollow. Instead of 

shaking loose bits like a maraca to make that famous sound, rattlesnakes clack

together segments of keratin — the same material found in your fingernails. 

They use three shaker muscles to vibrate the tips of their tails up to 90 times

a second, which is many times faster than you can blink! 

 

Transcription: 

If you're hiking pretty much anywhere in the US, this is one sound you don't want

to hear. The warning of a rattlesnake. Now, just because a rattlesnake's tail sounds

like a built-in maraca doesn't mean it works like one. There are no beads rattling 

about in here. So, what's really going on inside? If you opened up a rattlesnake's 

rattle and shook it, absolutely nothing would fall out. After all... 

Tim Colston: So, rattlesnake rattles are hollow. 

Narrator: That's herpetologist Tim Colston. He says the secret to that rattling sound

comes from the shell itself. It's made of keratin, the same hard substance as your

fingernails. The keratin is arranged in a chain of interlocking rings, which are 

hooked together by tiny grooves along their edge. Now, watch what happens 

to those rings when Colston shakes the rattle. Colston: Whenever I shake them 

very fast,they bump together, producing the sound. 

Narrator: Because the rattle is hollow inside, sound waves can bounce off the 

walls and echo, the same way shouting in a cave amplifies the sound. 

And the bigger the cave, or hollow rings in this case, the more amplification,

so the louder the rattle. But a big, hollow chamber can't get the job done on 

its own.That's where the tail muscles come in. Rattlesnakes are equipped with

three powerful shaker muscles at the base of their spine. 

These can contract so fast,they vibrate the rattle up to 90 times a second.

For comparison, the human eye blinks 15 to 20 times a minute. By vibrating so

quickly, the rattle makes a sound that hits between these specific frequencies.

And it just so happens that that range is best heard by mammals. It turns out,

that tail is custom designed to make predators like bears, raccoons, and weasels

listen up. Unfortunately, snakelets (yes, that's what baby snakes are called), 

don't have this warning signal. 

Colston: Whenever a rattlesnake is born, it just has a single button. 

It looks similar to the one, I don't know if you can see, that's on

the end here. Narrator: Without a second button to clack against, the baby rattle

can't make any noise. But every time they shed their skin, they add another 

button to the base of the rattle, which grows into the segment above, sort of like 

the structure of a Russian stacking doll. The rattle will keep growing until...snap! 

Just like your fingernails, those rattles are pretty fragile, and they can break off if

they get too long. In fact, the rattles rarely make it past eight to 10 rings before 

snapping off. Luckily, snakes shed their entire lives.

So the rattle will grow back good as new, which is good news for you hikers,

because that handy tail can mean the difference between an exciting day on the

trail and a painful trip to the hospital. 

 

Questions:

1. How would you know if there's a rattle snake nearby?

2. What's inside a rattlesnake's tail? What does it mate off? 

3. explain how it makes a sound.

작성일자
2021-05-04 오후 1:18:08
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