Difference Between Incomplete and Complete Metamorphosis

The key difference between incomplete and complete metamorphosis is that the incomplete metamorphosis has forms that resemble the mature form during the normal development and the life cycle has three forms; namely, eggs, nymphs, and adult, while the complete metamorphosis has only one adult stage and the life cycle has four forms; namely, egg, larva, pupa, and adult.

Metamorphosis means changing in form or transformation of body form. In simple words, metamorphosis refers to the process seen in animals where several different structural types can be distinctively identified in the life cycle after the embryonic stage during the normal development. Moreover, animals with metamorphosis undergo abrupt and conspicuous changes in body forms via cell growth and differentiation. Most of the insects, amphibians, and many invertebrates undergo metamorphosis. However, these animals show two types of metamorphosis namely incomplete metamorphosis and complete metamorphosis. It does not mean that one species can show both these two types, but it does suggest that certain species undergo incomplete metamorphosis while others undergo complete metamorphosis.

CONTENTS

1. Overview and Key Difference
2. What is Incomplete Metamorphosis
3. What is Complete Metamorphosis
4. Similarities Between Incomplete and Complete Metamorphosis
5. Side by Side Comparison – Incomplete vs Complete Metamorphosis in Tabular Form
6. Summary

What is Incomplete Metamorphosis?

There are three stages in incomplete metamorphosis known as egg stage, nymph stage, and adult stage. An adult female lays eggs upon mating with a fertile male. The egg case protects and covers the eggs when the proper conditions are present, the eggs hatch. The hatchlings represent the nymphal stage of the life cycle. Nymphs look mostly like adults, but smaller in size and their food habits are also the same as the adults. As the nymphs develop, they shed their exoskeleton to allow the body to grow large. Usually, after four to eight moults, the nymph becomes an adult, which usually has wings. At the adult stage, they do not moult and start wandering in search of opposite sexes for mating. Therefore, having wings in that stage benefits them.

Cockroach, grasshoppers, dragonflies, and bugs are some of the insects that show incomplete metamorphosis and their life cycles have only three distinct stages. Some species such as mayflies have aquatic nymphal stages, called naiads. They have gills in the abdomen and look very different from their adults.

What is Complete Metamorphosis?

The life cycle of complete metamorphosis has four different stages namely egg stage, larval stage, pupal stage, and adult stage. Eggs from a mated female reach the larval stage. Usually, the larva is completely different from the adult in their shape, size, food habits, etc. Caterpillar is the larva of butterfly, and they are completely different from each other, but the germplasm in both are the same.

During the larval stage, they are voracious feeders and store much food inside them to be ready for the next stage of their lifecycle. Larva makes a cocoon around it and stays inside without eating and moving. It is their pupal stage, and the pupa develops into an adult during this stage.

Finally, the pupal stage becomes an adult after completion of the development and comes out of the cocoon. And, this stage could range from four days to many months depending on the species. However, frogs and other amphibians also undergo complete metamorphosis, but there is no stage inside a cocoon. Frogs first lay eggs, followed by tadpoles with gills and froglets with lungs and tails, finally to become an adult frog.

What are the Similarities Between Incomplete and Complete Metamorphosis?

• Incomplete and Complete Metamorphosis are two types of metamorphosis seen in insects.
• Both types have common stages such as eggs and adult.
• Also, both terms concern the life cycles of insects.

What is the Difference Between Incomplete and Complete Metamorphosis?

Metamorphosis can be either incomplete metamorphosis or complete metamorphosis. Incomplete metamorphosis consists of three stages namely eggs, nymphs and adult while complete metamorphosis consists of eggs, larvae, pupa and adult. Therefore, this is the key difference between incomplete and complete metamorphosis.

Furthermore, in incomplete metamorphosis, middle stage; nymphs resemble the adult from appearance. But, complete metamorphosis does not show any similar stages. Thus, it is another difference between incomplete and complete metamorphosis. Considering some examples; insects such as aphids, crickets, grasshoppers, praying mantises, cockroaches, termites, dragonflies and lice show incomplete metamorphosis while insects such as beetles, flies, ants, bees, butterflies, moths, fleas and lacewings show complete metamorphosis.

Below is an infographic on the difference between incomplete and complete metamorphosis.

Summary – Incomplete vs Complete Metamorphosis

Incomplete and complete metamorphosis are two types of metamorphosis shown by insects. In incomplete metamorphosis, life cycle consists only of three stages, and the middle stage resembles the mature form from the appearance but differs from the size. The three stages are eggs, nymph and adult. On the other hand, in complete metamorphosis, life cycle consists of four distinct stages. They are eggs, larvae, pupa and adult. Thus, this is the difference between incomplete and complete metamorphosis.

Reference:

1. “Metamorphosis.” Wikipedia, Wikimedia Foundation, 21 Dec. 2018. Available here  
2. Kazilek. “Metamorphosis – Nature’s Ultimate Transformer.” Kazilek, 29 Apr. 2011. Available here 

Image Courtesy:

1.”Grasshoppermetasnodgrass”By S.E. Snodgrass (Public Domain) via Commons Wikimedia  
2.”Holometabolous vs. Hemimetabolous”By Username1927 – Own work, (CC BY-SA 4.0) via Commons Wikimedia