Larva

A larva is a special young form that many animals have before they change into their adult shape, a process called metamorphosis. Many animals, like insects, some arachnids, amphibians, and cnidarians, go through a larval stage in their life cycle.

Larvae often look very different from the adults they will become. For example, caterpillars turn into butterflies. They might have body parts that adults don’t have, and they often eat different foods. Some tiny spiders even have three pairs of legs as larvae but get a fourth pair when they grow up.

Larvae are usually suited to different places than adults. This helps protect them from animals that might eat them and avoids competition for food. For instance, tadpoles, the young of frogs, live in water, while adult frogs live on land. By living in different places, larvae and adults can stay safe and find their own food.

During their larval stage, animals eat to grow and change into adults. Some larvae, like those of polychaetes and barnacles, can move around, helping them spread to new areas, while the adults cannot move. In social insects like bees and wasps, special workers feed the larvae until they become adults.

In a few cases, larvae may stop developing and stay in their young form forever, a process called neoteny. This happens in some newts. It’s also not always true that a larva shows us how the animal’s ancestors looked, since larval forms can evolve separately from adults.

Selected types of larvae

Insect larvae

Insects called Endopterygotes go through a special change called complete metamorphosis. This includes a larval stage, meaning they look very different when they are young compared to when they are adults.

There are four main types of endopterygote larvae:

1. Apodous larvae – these have no legs and a soft body. Their head shapes can vary depending on their family.
2. Protopod larvae – these have many different shapes and look unlike normal insects. They come from eggs with very little food inside.
3. Polypod larvae – also called eruciform larvae, these have extra small legs on their abdomen along with the usual legs on their chest. They are soft, don’t move much, and stay close to their food. Caterpillars of moths and butterflies are a good example.
4. Oligopod larvae – these have well-developed heads and mouthparts like adults, but no complex eyes. They have six legs and no extra legs on their abdomen. They can be either long-legged hunters or short-legged burrowers.