Ecological Investigation Animals and Plants



Dragonflies Birds Amphibians Flowers Floating Plants Other Plants Animals from Outside
 

　　A Dragonfly and a damselfly  are like the dancing dragons in the sky. Their wings are composed of 4 individual tegula .  They can make a turn in a short time to catch other insects in the sky, so we call them "the dragon in the sky". Here is a report about their life circle.


【Tell the larvae of a dragonfly and a damselfly】－Shu-Wei

　　The larvae of dragonflies and damselflies called nymphs (the larval form) can be found in all 4 wetlands. Their common features are as follows. They like to live at the bottom of the wetlands , beneath the water surface or in the spirogyra. The body color is usually dark brown or dark green without wings. They use gills to breathe. When the oxygen in the water is not enough, they'll get out of water surface on the rocks or leaves to get fresh air. They like to catch other invertebrates or even vertebrates such as tadpoles and fish. In the larval stage, some  species can live for 2 to 3 months, some can live for 1 to 3 years, and some can live as long as 7 to 8 years to complete a generation. These nymphs live and grow in the lake and molt their shells 8 to 14 times before they are ready to hatch into adults. Even though the larvae of dragonflies and damselflies are quite similar, there are still some differences between them. Let's check them out!
  (Please look at the pictures and try to find the differences)

                                                                  
pic1. A dragonfly nymph, whose abdomen ends in three short spines and whose gills are held
         internally

pic2. The body of damselfly nymph is more slender with posterior tracheal gills.

                                                                       pic3. As the appearance of both dragonflies damselflies differs, so do their shells after eclosion. 
【The differences between an adult dragonfly and an adult damselfly】
   －Jia-Yu and Zih-Wen

　　Although many insects perform mating, it is uncommon among dragonflies. Dragonflies copulate while in flight, the male lifting the female in the air. Damselflies copulate while perched, sometimes flying to a new perch.

A male dragonfly has sexual organs  inside his belly with an opening, and he has another opening  which the sperms go out. The male dragonfly uses his superior anal appendages to connect or copulate with the female dragonfly. For the female dragonfly, she has an opening used to oviposit and copulate.. 

　　

There are three parts of dragonfly's copulation:

1. Sending the sperms: The mature male dragonfly bends his stomach and sends his sperms to a bag
                                       which saves the sperms. After he finishes this action, he starts looking for the
                                       female dragonfly.

2. connecting: When the male dragonfly finds a female dragonfly, he would catch her head by his feet
                        and connects her chest. Then they are in the posture which  the male dragonfly is in
                        the front and the female dragonfly is in the back..

3. Copulating: After the connection, if the male dragonfly want to copulate with the female dragonfly,
                         he will make it with her. After the copulation, the female dragonfly will breed on the
                        water. Some couples do the copulation on the stones or the branches, and some do it
                        as flying in the air.


pic4. After reading the above paragraph, can you tell which the male dragonfly is ?

　

<Here goes tiny damselflies> by Yi-Chen and Mei-Cin
        In summer time, it's really hard to take photos of rapidly flying dragonflies with regular digital cameras unless they copulate. However, in winter time, dragonflies are rarely seen but damselflies which don't keep flying are. So we took some pictures of damselflies with the best camera at school, as follows.

                                                                      pic5. A hunchbacked damselfly(Pseudagrion pilidorsum pilidorsum) stops on a lotus leaf at the
         fourth wetland.

                                                                      pic6. The smallest damselfly(Agriocnemis femina oryzae)，has white powder on the chest of a male
         adult.

                                                                        

pic7. A green damselfly (Coeliccia cyanomelas) stops on an aquatic herb(Schoenoplectus validus  T.
        Koyama) at the first wetland.

【Comparison of dragonflies between damselflies】－by Chi-Lin

While both dragonflies and damselflies belong to the Odonata and share many common features, there are a number of noticeable differences as well. Here are three of them.

1. An adult dragonfly (Anisoptera) has  relatively stout body , and the wings are extending to each side while the dragonfly is perched. Damselfly bodies are slender by comparison, and wings are held above the body while at rest.

2. The flying speed of a dragonfly is much faster than that of a damselfly.

 Luckily, we could take a shot of a scarlet dragonfly(Crocothemis servilia servilia)on the dead wood in the third wetland without being noticed.

pic8.A scarlet dragonfly(Crocothemis servilia servilia) stops at the third wetland.

3. The compound eyes of a damselfly are obvious and quite apart, which makes its head look like a dumbbell. Oppositely, the ones of a  dragonfly are closer. 

Try this quiz, do you know what kind of the dragonflies which flied by the hundreds?

Hint: Their wings are very thin. The answer is on the page called “Summer Camp.”


　
                                                                                

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