TOEFL Speaking Task 4 Practice 010Nature

Narrator:Listen to part of a lecture in a Biology class.

Professor:So, of course, many animals live in groups with others of their species, and there are benefits to living together in groups, it can help animals survive. But there are also certain disadvantages. So today we're going to talk about two disadvantages of living in groups for animals. One disadvantage is that animals that live in groups may be more visible to predators. If there's a big group of animals, predators are more likely to spot them than they would an individual animal on its own. So sometimes animals in groups may be more vulnerable to being captured by predators. For instance, sardines, really small fish, swim in groups, and other larger ocean animals, like some kinds of whales, eat them. So while a whale probably wouldn't notice one sardine, it'd see a group of sardines very easily and thus be able to capture them for food. Another disadvantage has to do with caring for the young. In a large group, there are a lot of young animals around and it can be difficult for animals to find or identify their own young. And they may end up taking care of other animals' young instead. So their own young may not get the care they need. For example, some bats live in caves, and with one type of bat, millions of them live together in the same cave. And with young bats so crowded together in the cave, it's sometimes hard for a mother bat to find her babies. So when a mother bat returns from finding food to feed her babies, she might end up feeding the babies of another mother bat, meaning her own babies don't get fed.