Insects and arthropods

Watch the video about insecst and arthropods and read the transcript

Video transcript

Insects and arthropods

More than three quarters of the world’s animal species are arthropods. They are an essential part of our ecosystem.

Although arthropods come in all shapes and sizes they all have some things in common. They are all invertebrates. This means they don’t have a backbone. They all have a skeleton on the outside of their bodies called an exoskeleton.

Their bodies are made up of segments and they have many pairs of jointed legs.

They also have bilateral symmetry. This means that the left side of an arthropod is a mirror image of the right.

The largest group of arthropods is insects.  An insect’s body is divided into three parts: the head, the thorax and the abdomen.

The second largest group is crustaceans. This group includes lobsters and crabs.

Arachnids include spiders and scorpions. Nearly all arachnids live on land and are hunters. Like insects, arachnids have a segmented body. However, whilst insects have three pairs of legs, arachnids have four pairs.

The last group of arthropods is the millipedes and centipedes. These creatures have many pairs of legs, one or two on each body section.

To survive, all arthropods need shelter, food and a safe place where they can reproduce. They can be found in many different environments and arthropods can adapt to their habitats. Spiders spin webs to catch prey, while hermit crabs use empty shells to give them protection and camouflage.

Bees take their food from the nectar in the plants around them.

Some arthropods such as beetles live alone. Others such as ants and bees live in huge well-organised communities.

All arthropods want to reproduce. Because there are so many different types of arthropods there are different ways in which they are born, develop and grow. Some arthropods like spiders and bees lay many eggs in protected places, for example under leaves or in a hive. When they hatch, the young look like the adults.

A few arthropods like the scorpion give birth to live young, which are carried until they are able to survive alone. Some arthropods have a life cycle where the egg hatches to reveal a larva, a grub-like creature. After a while the larva becomes a pupa. It will now gradually change or metamorphose to become an adult. A butterfly’s life cycle is a good example of this