Dominic Corsini has an extensive educational background with a B.S. in Secondary Biology and General Science with a Minor in Environmental Education, an M.Ed. in Educational Leadership, an M.S. in Biology, and a K-12 Principal Certification Program. Corsini has experience as a high school Life, Earth, Biology, Ecology, and Physical Science teacher.
Differences in Appearance
Below are pictures of two insects. Do you know what they have in common?
At first glance you may not think these two insect have much in common. One has wings, bright coloration and a long slender abdomen. The other is drab, lacks wings, and has a rounded abdomen. Aside from each having six legs, it doesn't appear there is much in common at all. If you are of this mindset then congratulations, you are like most other students who've come through my classroom. And, like most students, you are incorrect to assume these insects have little in common.
That is because these two photos are of the same insect. They look different because of metamorphosis. Metamorphosis is a process by which an organism develops after birth. It is often accompanied by stark changes in appearance between juvenile and adult life stages.
The above pictures are both of a dragonfly. The initial picture shows the dragonfly during an aquatic phase of its life. In this phase, the dragonfly is known as a nymph. Eventually, the dragonfly will undergo metamorphosis, emerge from this nymph phase, and take to the sky. The second picture shows an adult dragonfly after metamorphosis. This is likely the image most people are familiar with.
Dragonflies are only one example of organisms that undergo metamorphosis. Other, more common examples include frogs and butterflies. Most people realize that frogs come from tadpoles and that butterflies come from caterpillars. However, they may not know these organisms represent only the tip of the iceberg.
The process of metamorphosis has been observed in sponges, flat worms, mollusks, segmented worms, sea urchins, and even some fish. Although sometimes overlooked by the casual observer, metamorphosis is interwoven into the fabric of life itself.
Types of Metamorphosis
Nowhere is metamorphosis more common than in the insect world. Within this realm there are two general types of metamorphosis. They are complete metamorphosis, and incomplete metamorphosis. Complete metamorphosis contains a pupa stage, while incomplete metamorphosis does not. The pupa stage often represents the greatest change from larvae to adulthood. To assist in your understanding, take a look at the following illustration.
On the left side of this image you'll notice what an incomplete metamorphic life cycle looks like. In this case, we're looking at grasshoppers. During this type of metamorphosis, organisms slowly transition from the egg stage to the adult stage. During their adolescent stage insects are often referred to as nymphs.
The dragonfly nymph shown earlier was undergoing incomplete metamorphosis. It would continue to experience slow changes to its body until ready to emerge as an adult. Other common examples of organisms that undergo incomplete metamorphosis include frogs and cockroaches.
To the right of the image you'll notice a butterfly. Here, we can see a sharp transition between the caterpillar stage (known as a larvae), to the adult stage. The item many people recognize as a cocoon is actually the pupa. This pupa stage can clearly distinguish complete metamorphosis from incomplete metamorphosis.
Butterflies and moths all have this stage and undergo complete metamorphosis. Additional examples include ladybugs and bees.
Metamorphosis occurs throughout the natural world. It is a process by which an organism develops after birth and is often accompanied by stark changes in appearance between juvenile and adult life stages.
There are two basic types of metamorphosis. They are complete metamorphosis and incomplete metamorphosis. Complete metamorphosis contains a pupa stage, while incomplete metamorphosis does not.
The pupa stage (cocoon) often represents the greatest change from larvae to adulthood. Butterflies, moths, ladybugs, and bees are example organisms for complete metamorphosis. Grasshoppers, dragonflies, frogs, and cockroaches are example organisms that undergo incomplete metamorphosis.
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