Fill in the Blanks Animals (unit 5)Online version Reading comprehension / vocabulary practise by Patrick Verheyen 1 protection prey omnivores protection attacked carnivores avoiding fearsome experts reproductive defend primarily defensive Piranhas Scientists in the UK have announced that the piranha fish's reputation as a killer may well not be deserved . The fish , which is found in the Amazon in Brazil , have been portrayed as deadly that work in shoals to overwhelm their and strip it of its flesh in seconds . However , from St Andrews University say that piranhas are that mainly eat fish , plants and insects . They form big groups not to hunt but to themselvers against other predators , according to the team . " Previously it was thought piranhas shoaled as it enabled them to form a cooperative hunting group , " said Professor Anne Magurran . " However , we have found that it is a behaviour . " Piranhas can be by animals such as dolphins , caimans and large fish , so forming a shoal is a good way of being killed . Piranhas of age stay in the middle of the group for and the size of the shoal differs according to the level of risk . When the water level is high , the fish form small groups as there is space to escape , but when the water level drops , they form large groups as against predators .