Question

A pupa forms during the life cycle of some _____. a. crustaceans c. annelids b. echinoderms d. insects

Short answer

The correct answer is d. insects.

Step-by-step solution

Understanding the Pupa Stage

First, we need to understand what the pupa stage is. The pupa is a life stage in some animals, particularly those that undergo complete metamorphosis. This is an inactive stage where the organism is usually encased in a protective covering and undergoes transformation into its adult form.

Identifying Animals with a Pupa Stage

Next, we identify which groups of animals undergo complete metamorphosis. Complete metamorphosis involves four distinct life stages: egg, larva, pupa, and adult. This process is most commonly seen in insects, such as butterflies, beetles, and moths.

Evaluating Each Option

Now, we evaluate each given option to determine if they undergo a pupa stage: - Crustaceans: Typically do not have a pupa stage; they mostly undergo molting as they grow. - Annelids: Do not undergo metamorphosis; they grow through direct development. - Echinoderms: Do not have a pupa stage; they undergo a different form of development called metamorphosis but without a pupal stage. - Insects: Many insects undergo complete metamorphosis that includes the pupa stage.

Conclusion and Answer Selection

Based on the information from the previous steps, we conclude that the correct answer is that certain types of insects have a pupa stage in their life cycle.

Key concepts

Complete Metamorphosis

Complete metamorphosis is a fascinating process in which certain insects undergo a series of four distinct life stages. These stages include the egg, larva, pupa, and adult. The transformation is drastic and is known for being one of the most complex life changing phenomena in the insect world.
Insects that go through complete metamorphosis experience a radical change in form and function.

• Egg: The life cycle starts here, where the embryo is formed.
• Larva: Following the egg stage, larvae emerge and are mainly focused on eating and growing.
• Pupa: This is a transformative stage where the insect begins its dramatic change.
• Adult: The final stage, where the insect reaches full maturity and is capable of reproduction.

Complete metamorphosis allows for a clear separation of life stages, enabling insects to exploit different resources at each stage of their life, providing them with an evolutionary advantage.

Pupa Stage

The pupa stage is a critical period in the life cycle of insects that undergo complete metamorphosis. During this stage, the insect is typically immobile and encased in a protective covering, known as a chrysalis or cocoon.
It is often seen as an inactive phase, but it's actually a time of intense internal change. Inside, the larva's tissues are broken down and reorganized into the adult form.
The pupa stage can last from a few days to several months, depending on environmental conditions and the specific insect species. This stage plays a crucial role in protecting the insect from predators while it undergoes transformation.

• Serves as a protective stage.
• Facilitates complex internal reorganization.
• Duration varies across species.

Insect Development

Insect development is a progressive and organized process that allows insects to transition from one life stage to another. This encompasses the entire journey from egg to adulthood.
Each stage has specific characteristics and aims:

• Eggs hatch into larvae, the growth stage.
• Larvae consume food voraciously to store energy for later stages.
• The pupa stage protects and transforms the insect internally.
• Finally, the adult stage focuses on reproduction.

Insects develop through complete metamorphosis to avoid competition between juveniles and adults for food and habitat, thus increasing survival rates.
This method of development is seen in many common and diverse insect species, including butterflies, beetles, and flies.

Insect Metamorphosis

Insect metamorphosis is the process of change all insects go through as they develop into adults. However, the extent of metamorphosis can vary significantly between insect species.
Insects are generally divided into those undergoing complete and incomplete metamorphosis. Complete metamorphosis, as discussed, involves pronounced changes as the insect passes through distinct stages.

• Complete metamorphosis includes a pupal stage.
• Incomplete metamorphosis skips the pupa stage and has less drastic changes.

While not all insects undergo complete metamorphosis, those that do often experience significant benefits, such as specialization of different life stages for specific actions like eating or reproducing.
Understanding these patterns helps entomologists and students alike grasp the importance of biological adaptation and survival in the insect kingdom.