Listen to part of a lecture from a biology class.

问题

Many animals in the wild actively hunt for prey, but hunting prey actively, possibly covering a lot of territory, finding them, tracking them down, requires predators to use a lot of energy. Some predators have developed more efficient ways to hunt that expend less energy. Instead of sitting and waiting for their prey to come to them, they capture or draw them in without the kind of effort involved that it would take to actively hunt them down. Some animals do this by modifying their environment to build hidden traps that will surprise and capture passing prey animals. Building a trap requires an initial investment of energy and effort for the predator, but after the trap is built, the payoff is that the predator can sit and wait for its prey to be captured in the trap. So it can be an efficient hunting strategy. An insect called the antlion does this by digging a hole in the sand of, say, a riverbed and climbing down into the hole to wait for smaller insects, like ants, to pass by and accidentally fall in where the antlion is waiting below. Much better than stalking, scouring around the riverbed for them. Other animals use objects that work as bait to lure or attract prey. The object they use may look like a food item to lure the prey animal, so when the prey animal sees the object, it's attracted and approaches, and once it's within reach, the predator can easily capture it. Thus, by luring the prey to them, the predator doesn't have to move around so much in pursuit, which is a much more efficient method of hunting. For example, a type of bird called a heron, if you've ever seen one, they have long legs and stand nearly motionless in shallow water, looking for fish. To this end, they also cleverly pick up plant seeds from the nearby ground to drop onto the surface of the water, which the floating seeds look like food to fish. So they swim up to the surface where the heron is waiting.