DRAGONFLIES AND BUTTERFLIES: HOW ARE THEY DIFFERENT?
dragonflies and butterflies belong to the
kingdom Animalia, phylum Arthropoda, and class Insecta. Insects
most numerous animals
The second stage, known as the Paleoptera stage, involves the formation of wings on the insects. These wings where held straight out or straight back. They were also long and rigid. This was a very important step in the evolutionary process of insects. Developing wings allowed them to do several things. Insects could now fly great distances and therefore disperse plant life, travel to locate new sources of food, find mates, and escape predators. Along with the development of the wings came a new more complex type of metamorphosis, the hemimetabolous development. The hemimetabolous development is an incomplete metamorphosis, which means that some change will take place. In this process, the egg is deposited into the water where it develops into a nymph. The nymph resembles the adult, but there is not a pupa stage: however, the nymph will go through several molts before actually becoming an adult. It is here at this stage that we find the first fossilized remains of a dragonfly. It dates back to the late Carboniferous period about 300 million years ago and it was in the order of Paleodictyoptera, which is the precursor of the order Odonata.
Neopterous stage is the third stage in the evolutionary process of the insect. Neopterous means "new wing." This new wing could now be folded back over the insect's abdomen through a new addition known as a flexon that allowed the wing to bend at the base. This allowed insects to crawl into smaller spaces to find food. These insects maintained a hemimetabolous development, which can be seen today in crickets, cockroaches, and grasshoppers.
The final stage of the insect evolution is the holometabolous development or a complete metamorphosis. A group of neopterous insects developed this new form of metamorphosis. This development shows that the larval and the adult form are completely different from one another. An example of this process is the butterfly.
The dragonfly, according to fossil evidence appeared first in the evolutionary process and therefore its life cycle reflects the hemimetabolous development. As shown in the dragonfly life cycle below, the egg is laid in or near water, usually on a floating plant.
Dragonfly Life Cycle
Figure 1: http://www.kidfish.bc.ca/images/dragonfly_life_cycle.jpg
The egg can take anywhere from 7 days to several months to hatch. Once the egg hatches, the dragonfly will spend most of its life in the larval stage (nymph) underneath the surface of the water using gills to breathe and feasting on both vertebrates (tadpoles and fish) and other invertebrates. The larval stage can last anywhere between 3 months and 10 years depending upon the species. During this time, the larvae can go through approximately 10 to 20 molts. The final stage in the cycle takes place on a fixed object usually a plant some distance from the water. The dragonfly can live as long as four months in the adult stage.
at the life cycle of the butterfly life cycle (Figure 2), one sees a
involved and evolved process. Like the
dragonfly, the butterfly begins life as an egg but not laid on a plant
water but rather on a leaf. When the
egg hatches, caterpillar
Butterfly Life Cycle
(Larvae) is born. The caterpillar immediately begins eating the leaves and the flowers around it. Just like the dragonfly, the caterpillar will also go through many molts during this stage of its cycle. By the time the caterpillar is ready to pupate, it will have increased in size up to a thousand times. When the caterpillar is ready, it will form the chrysalis or pupa where it will rest and transform into the final stage of adulthood – a butterfly. The average lifespan of an adult butterfly can range from 20 to 40 days; others may live up to six months.
and dragonflies differ not only in life cycle but they also differ in
habitat, diet and morphology.
Butterflies can be found in various environments: from
deciduous forests and from wetlands to farmlands. They
also are known to migrate in order to avoid adverse weather
or environments (enchantedlearning.com, 2006).
Some butterflies like the Monarch migrate thousands of miles
others like the Painted Lady migrate very short distances.
Dragonflies like to be around moist areas
such as wetlands, ponds, streams, and lakes.
They live most of their lives as nymphs in the water and will
there as adults to mate and lay their eggs.
As for their diet, butterflies will uncoil their proboscis
drink the nectar from flowers where the dragonfly much prefers flying
like bees and unfortunately butterflies for their meals.
Morphologically speaking, dragonflies and
butterflies share some general characteristics. Both
have three bodily segments: head, thorax and abdomen.
Both have compound eyes, wings, and six legs, but
there is where the
Although butterflies and dragonflies show some similarities in structure and development, they are of a totally different order. Each has developed in a unique manner to fit the niche in which it occupies. Butterflies help to pollinate flowers and are food for the dragonflies. Dragonflies are ancient insects that have withstood the test of time and change. Both make the world a little more beautiful and special.
Butterflies. Retrieved August 12, 2006, from Kids' Planet: Defenders of Wildlife Web site: http://www.kidsplanet.org/factsheets/butterflies.html
Evolution and Ancestors. Retrieved August 1, 2006, from Dragonflies – Living Fossils Web site: http://skurvits.tripods.com/dragonflieslivingfossils/index.html
Ingram, Jay (August 29,2000). Dragonfly’s evolution of flight. Retrieved August 1, 2006, from Discovery Channel Website: http://www.exn.ca/Templates/printstory.asp?PageName=Discovery&story_id=2000081857
Insects Life Cycles. Retrieved August 18, 2006, from Earth-Life Web Productions Web site: http://www.earthlife.net/insects/lifecycles.html
Kendall, David (2005). Insect Life Cycles. Retrieved August 10, 2006, from Kendall Bioresearch Services Web site: http://www.kendall-bioresearch.co.uk/life.htm
Using Live Insects. Retrieved August 13,2006, from Center for Insect Science Education Outreach Web site: http://insected.arizona.edu
(1996-2006). What is a Butterfly?. Retrieved August 15, 2006, from Enchanted Learning http://www.enchantedlearning.com/subjects/butterfly/