Looking at insects: more keys In this lesson, you will be looking at insects. This includes using a key to identify different kinds of insects as well as observing an insect in its environment. Some examples of insects Insects are by far the biggest group of animals. There are probably about 900 000 different types of insects. How many different types of insects can you think of? See if you can write down at least five. The insect group includes animals such as silverfish, mayflies, dragonflies, grasshoppers, crickets, cockroaches, termites, earwigs, lice, thrips, bugs, cicadas, beetles, weevils, wasps, ants, bees, fleas, flies, mosquitoes, moths and butterflies. You might think these insects are very different from each other but they have a lot more in common with each other than with any other invertebrates. Did you have trouble thinking of the names of insects you have seen? No-one could possibly identify and name every single insect. This is why keys are really useful. Here is a key that you can use to identify some insects. Lesson 15/20 More about classifying animals 1
insects wings no wings flea 1 pair of wings fly 2 pairs of wings wings cover body wings stick out from body wings overlap cockroach wings don t overlap beetle Identification key for some insects wing veins thick wasp wing veins complex dragonfly Use the key to identify each of the six insects drawn below. Activity: What are some examples of insects? Write the name of each insect on the line under its drawing. a b c d State of New South Wales, Department of Education and Training, 2004 2 Living things
e f State of New South Wales, Department of Education and Training, 2004 Check your response by going to the suggested answers section. What is an insect? You can probably recognise and name a large number of insects, but what is an insect? What do all insects have in common? You already know that insects are invertebrates. This only indicates that insects do not have an internal skeleton. You are more interested in what insects do have. Now discover the things about an insect s appearance that make it different from anything else. There are basically four features of insects that make them different from other animals the body, eyes, antennae and legs. Look at each of these features, one at a time, to build a picture of an insect. Lesson 15/20 More about classifying animals 3
The insect body An insect has an interesting body. It is divided into three distinctive parts head, thorax and abdomen. mouthparts on head head thorax abdomen An insect s body State of New South Wales, Department of Education and Training, 2004 Incidentally, you have these parts too. The head is obvious. Your chest in your thorax you might have heard the space for your lungs called your thoracic cavity. And your abdomen is your belly, below your tummy button. Insect eyes The second identification feature of insects is the eyes. Insects can see in all directions at once because they have two large eyes known as compound eyes. This is why insects such as flies are so hard to catch! Some insects even have another three eyes. These are smaller and on top of their heads. simple eye compound eye An insect s eyes State of New South Wales, Department of Education and Training, 2004 4 Living things
Insect antennae The third feature of insects is the hair-like antennae. Some insects use their antennae for smelling! antenna Insect with antennae State of New South Wales, Department of Education and Training, 2004 Insect legs The last feature of insects is the easiest to observe the legs. If a creature is an insect then it must have six legs. These six legs are all attached to the thorax. jointed legs attached to thorax Insect legs State of New South Wales, Department of Education and Training, 2004 Lesson 15/20 More about classifying animals 5
Now that you have built up a picture of an insect, list the four main features used to identify insects. Activity: What is an insect? List the four main features used to identify insects. Check your response by going to the suggested answers section. You have been a good observer if you got all four features of insects correct. Did you think that wings were an identification feature of all insects? Many people do. But all insects do not have wings. Can you think of any insect that doesn t have wings? Fleas are one type of insect that do not have wings. Preparing for the Exercise Test your powers of observation by completing the following exercise. Go to the exercises section and complete Exercise: Looking at insects more keys. 6 Living things
Our classification system so far It is a good idea to have an overall plan of what fits in where. So, here is a chart that maps your progress. non-living all things living plants vertebrates fish amphibians reptiles birds mammals animals invertebrates cnidaria worms echinodermata molluscs arthropods crustaceans insects arachnids Our classification system Notice how this key (map, plan, chart) is different from the ones you have been using in this unit. But it is only different because it is turned on the side. To read it, start from the left hand side and go across to the right. The plan was too big to fit down the page. There are some technical terms used throughout this unit. Note the word use below. Cnidarian is one animal; cnidaria is more than one animal of that kind. Lesson 15/20 More about classifying animals 7
What did you achieve? Tick what you can do. give examples of insects list the main features of insects use a key to identify some insects 8 Living things
Suggested answers Check your responses against these suggested answers. Some examples of insects a b c d e f dragonfly cockroach lady beetle flea fly wasp. What is an insect? The four main features used to identify insects re: three body parts head, thorax and abdomen two large compound eyes a pair of antennae six legs attached to the thorax Lesson 15/20 More about classifying animals 9
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Exercise Living things Name Teacher Exercise: Looking at insects more keys Can you observe the classifying features on the drawings of insects below? Tick the features that you can see for each animal. 1 three body parts head, thorax and abdomen two large compound eyes a pair of antennae six legs attached to the thorax 2 three body parts head, thorax and abdomen two large compound eyes a pair of antennae six legs attached to the thorax 3 three body parts head, thorax and abdomen two large compound eyes a pair of antennae six legs attached to the thorax 4 three body parts head, thorax and abdomen Lesson 15/20 More about classifying animals 11
two large compound eyes a pair of antennae six legs attached to the thorax State of New South Wales, Department of Education and Training, 2004 12 Living things