青少新概念2Aunit5补充阅读材料ants.doc

INTERESTING FACTS ABOUT ANTS 1 Like all insects, ants have six legs. Each leg has three joints. The legs of the ant are very strong so they can run very quickly. If a man could run as fast for his size as an ant can, he could run as fast as a racehorse. Ants can lift 20 times their own body weight. An ant brain has about 250 000 brain cells. A human brain has 10,000 million so a colony of 40,000 ants has collectively the same size brain as a human. 2 The average life expectancy of an ant is 45-60 days. Ants use their antenae not only for touch, but also for their sense of smell. The head of the ant has a pair of large, strong jaws. The jaws open and shut sideways like a pair of scissors. Adult ants cannot chew and swallow solid food. Instead they swallow the juice which they squeeze from pieces of food. They throw away the dry part that is left over. The ant has two eyes, each eye is made of many smaller eyes. 3 They are called compound eyes. The abdomen of the ant contains two stomachs. One stomach holds the food for itself and second stomach is for food to be shared with other ants. Like all insects, the outside of their body is covered with a hard armour this is called the exoskeleton. Ants have four distinct growing stages, the egg, larva, pupa and the adult. Biologists classify ants as a special group of wasps. (Hymenoptera Formicidae) There are over 10000 known species of ants. Each ant colony has at least one or more queens. 4 The job of the queen is to lay eggs which the worker ants look after. Worker ants are sterile, they look for food, look after the young, and defend the nest from unwanted visitors. Ants are clean and tidy insects. Some worker ants are given the job of taking the rubbish from the nest and putting it outside in a special rubbish dump! Each colony of ants has its own smell. In this way, intruders can be recognized immediately. Many ants such as the common Red species have a sting which they use to defend their nest. 5 The common Bla