What is a Life Cycle?

A life cycle is a series of stages that all living things go through during their lives. It is a repeated pattern of change in nature that defines different stages in life. Understanding life cycles allows us to appreciate how the Earth is a self-sustaining system that continues life.

What are the Stages of Animal Life Cycles?

Animals have 3 or 4 stages of life cycles.

Here are examples of animals with a 3-staged life cycle.

Generally, animals with a 3-staged life cycle consist of the egg, young and adult stages.

Chicken

A chicken’s life cycle has 3 main stages: egg, young (chick), and adult (chicken).

It starts as an egg, which hatches into a chick after about 3 weeks. The chick then grows into an adult chicken in a few months, and the adult chicken can reproduce and lay eggs to start the cycle of life again.

Frogs

 

• Egg: A frog begins life as a fertilized egg. A female frog lays a lot of eggs at one time in a pond. The eggs float on water in a transparent jelly cluster.
• Young (tadpole): When the egg hatches into a tadpole, which looks very different from the adult frog. It does not have any legs! Instead, it has gills that allow it to breathe underwater. The tadpole swims, eats plants and algae from the water, and grows for several weeks. As they grow, they gradually develop legs, lose their tails, and their gills are replaced by lungs for breathing air on land.
• Adult (Frog): The young tadpoles transform into adult frogs through a process called metamorphosis. Adult frogs can live both in water and on land. They are capable of reproducing, and the female frogs lay eggs to start the life cycle again.

Cockroach

• Egg: The life cycle begins when a female cockroach lays eggs. These eggs are often contained in a protective case called an ootheca, which can hold multiple eggs. The ootheca is usually laid in a safe, hidden place.
• Nymph: The eggs hatch into nymphs, which are smaller versions of adult cockroaches but without fully developed wings and reproductive organs. The young look like the adult, hence it is called a nymph. They go through several moults, shedding their exoskeletons as they grow larger and gradually develop adult features.
• Adult: After the final moult, the nymph becomes an adult cockroach. Adult cockroaches have fully developed wings (in most species) and reproductive organs. They can reproduce, and the female can lay eggs, starting the life cycle anew.

Here are examples of animals with a 4-staged life cycle.

Animals with a 4-staged life cycle consist of the egg, larva, pupa and adult stages.

Butterfly

A butterfly’s life cycle has 4 main stages, and they usually only live for a few weeks on average:

• Egg: The life cycle begins when a female butterfly lays eggs on a plant. These eggs are tiny and can be round, oval, or cylindrical, depending on the species.
• Larva (caterpillar): The egg hatches into a larva, known as a caterpillar. Its main job is to eat and grow. It sheds its skin multiple times as it gets bigger, a process called moulting.
• Pupa: After reaching a certain size, the caterpillar forms a pupa and undergoes a transformation called metamorphosis. It does not move or eat during this stage, as its body changes into a butterfly.
• Adult (butterfly): The adult butterfly emerges from the pupa. The adult butterfly’s primary roles are to reproduce and lay eggs, and the life cycle continues.

Mosquito

• Egg: The life cycle begins when a female mosquito lays eggs on the surface of stagnant water. The eggs can be laid singly or in clusters, depending on the species, and they hatch within a few days.
• Larva: The eggs hatch into larvae (wrigglers), which live in water. The larvae feed on microorganisms and organic matter in the water. They come to the surface to breathe through a breathing tube and undergo several moults as they grow.
• Pupa:  The Pupae do not eat in this stage. It is a time of transformation, as the mosquito develops into an adult.
• Adult: The adult mosquito emerges from the pupal case and rests on the water’s surface until its body hardens and wings dry. Adult mosquitoes are capable of flying, feeding and reproducing. Females typically require a blood meal to develop eggs, thus continuing the life cycle.

Beetle

• Egg: The life cycle begins when a female beetle lays eggs. These eggs are often laid in protected environments, such as soil, wood, or plant material, depending on the beetle species. The eggs hatch within a few days to weeks.
• Larva: The eggs hatch into larvae, commonly known as grubs. Larvae look very different from adult beetles and primarily focus on feeding and growing. They can be worm-like or have legs, depending on the species. The larval stage can last several months to years, with multiple moults as they grow.
• Pupa: After the larval stage, the beetle enters the pupal stage. The pupa is usually inactive and enclosed in a cocoon or protective case. Inside the pupa, the beetle undergoes metamorphosis, transforming into its adult form. This stage lasts from a few days to several weeks.
• Adult: The adult beetle emerges from the pupa with fully developed wings, legs, and exoskeleton. Adult beetles are capable of reproduction, and the female can lay eggs to start the life cycle anew.

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