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Practice Reading: Reading and Writing Fill in the Blanks ID: #51261 Invasive Species
Instructions
Invasive  species  can    biodiversity  and  drive  resident  species  to  the  brink  of  extinction.  But  how  do  these  interlopers  fare  so  well  in  unfamiliar  territory?  One  idea  is  that  they've  escaped  their  enemies,  for  example,  the    that  keep  them  in  check  on  their  home  turf.  But  a  study  in  the  journal  Biology  Letters  suggests  that  notion  doesn't  always  stand  up.  Because  at  least  one  kind  of  invasive  shrimp  is  an  even  bigger  pest  when  it  has  a  parasite  on  board.  The  scientists  were  studying  a    shrimp  commonly  found  in  England.  Fishermen  brought  the  shrimp  to  Northern  Ireland  in  the  1950s  as  a  tasty  treat  for  local  trout.  Well,  the  shrimp  liked  the  new  digs.  So  much  that  they've  all  but  eliminated  the  native  shrimp  species.  The  strange  thing  is,  they  may  have  parasites  to  thank.  In  some  streams,  70  percent  of  the  invaders  are    with  an  intestinal  worm  that  doesn't  go  for  the  native  shrimp.  But  this  gut  worm  doesn't  slow  them  down.  In  fact,  infected  shrimp  eat  30  percent  more  prey  than  those  that  are  parasite-free.  Which  perhaps  is  not  surprising.  If  you  had  a  worm  that    a  quarter  of  your  body  weight,  you'd  eat  more  too.

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