Odonata
Odonata is the order of insects that includes dragonflies and damselflies.To the human eye, their shining colors① and delicate-looking wings make thembeautiful creatures to behold. In the natural world, however, they are fearsomepredators. Dragonflies and damselflies get their name from the powerful serratedjaws they use to tear apart their prey. The word odonata means “toothed jaw.”
Dragonflies and damselflies are often confused with each other becausethey are very similar. Close observation reveals the differences between them.The most obvious difference is the way they hold their wings while at rest.Dragonflies hold their wings out to the side while damselflies fold their wingsback. Dragonflies have very large eyes that seem to cover the entire face becausethey are so close together that they touch each other. Damselflies’ eyes aresmaller, and there is a space between them. Dragonflies are larger and strongeranimals than damselflies and fly longer distances. Thus, they can be found inwoods and fields away from the water. Damselflies are not such strongfliers andare most often seen around the edges of ponds and streams since they do notnormally fly far from the water.
The largest odonata living today are the Hawaiian endemic dragonfly
and the Central American damselfly, each of these species having a wingspanof 19 centimeters. The smallest is the libellulid dragonfly, native to east Asia,with a wingspan of just 20 millimeters. Fossils have been discovered that provethat dragonflies have been in existence for over 300 million years. The largestdragonfly fossil ever found belongs to the now-extinct meganeura monyi, whichlived 300 million years ago and had a wingspan of 75 centimeters. This giantwas a fearsome predator indeed, which feasted on small amphibians as well ason other insects.
Dragonflies and damselflies both lay their eggs on or just below the surfaceof the water in a pond or stream. Some species lay their eggs on the stem ofan aquatic plant. The babies emerge from the eggs in the form of nymphs.They live underwater, breathing through gills and preying upon water insects,tadpoles, small fish, and even other nymphs. They hunt by hiding in theshadows at the bottom of a pond or stream, waiting for prey animals to swimby. They have a special lip that they can extend far forward in order to grabtheir prey when it comes close. Depending on the species, they live this wayfor several months or even several years. As the nymph grows, it sheds its skinseveral times. Finally, it leaves the water and sheds its skin one last time. Theadult emerges, ready to live the next few weeks or months on land and in theair. The adults do not live for more than four months, and many species live asadults for only a few weeks.
The exceptional visual abilities and flying skills of dragonflies and
damselflies make them very adept hunters. Their special eyes give them a nearly360-degree field of vision, and they can detect even the smallest movement orflash of light caused by other flying insects. They have two sets of wings that canmove independently of each other. This gives them great maneuverability① inthe air, which is important to these creatures because they catch their prey whileflying. They can hover, make sharp turns, and fly backward. Some species ofdragonflies can fly 60 kilometers an hour or more. Their prey consists of flyinginsects such as mosquitoes, deerflies, smaller dragonflies, and butterflies andmoths. One species of dragonfly takes spiders out of their webs.
Bloodthirsty predators that they are, dragonflies and damselflies are preyfor other animals in their turn. The nymphs are eaten by fish, frogs, toads, andother aquatic creatures. In the adult stage, they are hunted by birds, frogs, andlarger dragonflies and damselflies. They might also be caught in a spider’s web.What goes around comes around.
Questions 1–6
Which of the facts below are true of dragonflies, and which are true of damselflies, according
to the information in the passage? On lines 1–6 on your answer sheet, write:
A if it is a fact about dragonflies only
B if it is a fact about damselflies only
C if it is a fact about both dragonflies and damselflies
1 They have sawlike jaws.
2 They hold their wings on their backs while resting.
3 Their eyes have a gap between them.
4 They can be seen in fields at a distance from ponds and streams.
5 The largest species has a wingspan of 19 centimeters.
6 The largest fossil has a wingspan of 75 centimeters.
Questions 7–13
Complete the notes about the life cycle of odonata below. Choose your answers from the
box below and write the correct letters, A–K, on lines 7–13 on your answer sheet.
A in the air
B with their lips
C tadpoles
D fliers
E near the water’s surface
F nymphs
G at the bottom of a pond
H months or years
I weeks or months
J swimmers
K with their wings
The eggs are laid 7 .The young dragonflies and damselflies,
called 8 , live underwater for a few 9 .
They eat small water animals, catching their food 10 . When
they are almost fully grown, they leave the water. The adults live for only a few11. They are skillful12 and catch their
prey 13 .
