How and why

Life in the oceans flourished during the Silurian. Large areas with warm and shallow water were perfect environments for many organisms to evolve and live in.

But why did vascular plants become so successful on land? Why were arthropods the first animals to live on land, and how did colonization occur?

Vascular plants

Vascular plants completely changed land surfaces. Their roots could bind sediments, thereby reducing erosion. They also provided shelter and food to the first land-dwelling animals.

All green plants use sunlight as their source of energy. By growing higher, they can get more sunlight and gain an advantage over shorter competitors.

In order to survive on land and grow higher, vascular plants evolved several new adaptations.



Cells with walls strengthened by cellulose and lignin.

Support which enabled plants to grow higher.

Surfaces covered with wax.

Protection against dehydration and UV radiation.

Stomata, tiny pores on plant surfaces.

Make it possible for plants to breathe, exchange carbon dioxide and oxygen with their surroundings.

Vein networks.

Transport water and nutrients between various parts of plants.

Root-like outgrowths.

Hold the plant in the soil, and take up water and nutrients.

Reproduction with spores.

Spores can survive dry conditions and be transported over long distances.

The first land animals

It is not easy to determine what life was like for animals that lived over 400 million years ago. But it is evident that living on land offered advantages.

Available on land was a new food source – plants. At first, there was also less competition and there were no predators of any kind on land.

The first land animals were arthropods such as arachnids (spiders, etc.), myriapods (centipedes, etc.) and insects. They evolved from marine arthropods, and from the beginning they were well suited to life on land due to two bodily features:

  • A hard external skeleton that gave support to the body and protected against water loss.
  • Jointed legs and flexible bodies enabled them to move well on land.