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Practice Reading: Fill in the Blanks (Dropdown) ID: #49906 Zebra Stripes
Instructions
How  did  the  zebra  get  its  stripes?  One  theory  holds  that  stripes  help  confuse  predators.  But  stripes  might  be    to  protect  zebras  from  ferociousinsects.  That's    to  a  study  in  the  Journal  of  Experimental  Biology.  Horseflies  are  abundant  in  Africa.  They  deliver  painful  bites  that  spread  disease  and  distract  animals  from  grazing.  The  flies  use  polarized  light  hitting  water  as  a  guide  to  places  to  mate  and  lay  eggs.  And  they  read  such  light  hitting  dark  mammal  hides  as  a  sign  of  a  blood  meal.  Zebra  embryos  start  out  dark  and  develop  their  white  stripes  before  birth.  Could  the  stripes  confuse  flies?  The  researchers  went  to  a  farm  infested  with  horseflies,  where  they  set  up  models  of  black  and  white  stripes  of  varying  angles  and  widths,  thus  changing  the    of  the  reflected  polarized  light.  They  tracked  how  the  patterns  affected  the  flies'  interest.  They  then  tested  models  of  horses  colored  black,  brown,  white  or  .  And  again  tracked  the  effect  on  flies.  Turns  out  that  the  black  and  white  stripes  on  a  zebra  are  optimal  for    a  horsefly's  .  Meaning  that  zebras  may  have  evolved  stripes  to  ward  off  disease-carrying  insects,  and  to  dine  in  peace.

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