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 are 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 a group 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 kind of whales, eat them. So while a whale probably wouldn’t notice one Sardine, it would 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 to 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.
Using points and examples from the lecture, explain two disadvantages of living in groups for animals.
The lecture is focusing on two disadvantages of living in a group for animals. One disadvantage is that animals living in groups are more visible and vulnerable to predators. Take sardines as an example. They swim in groups and they are prey for some large animals such as whales. Although it may be hard for a whale to notice one little Sardine, it is able to see a group of them and capture them for food. Another disadvantage is that living in groups set great barriers for animals to identify their own young and thus have them in good care. For example, one type of bats live together in the same cave with millions of them. With too much bats in the same cave, a mother bat may find it’s hard to find her own baby and she may end up feeding the babies of another mother bat, leaving her own babies with no food.
vt. 欣赏；感激；领会；鉴别 （appreciate的第三人称单数）
They don't have any confidence that houses will appreciate in value.(TPO49-20)