The Explosion That Starts Life

POOF! And there goes the first phylum! GIF by GIPHY

Ever wonder how kingdoms of animals ever started? What causes them? When? And ultimately, HOW? It’s CAMBRIAN EXPLOSION!

Cambrian Explosion is a relatively rapid appearance of animal kingdoms or known as phyla – a taxonomic term which means the primary kingdom of animals – which happened around 530 million years ago and lasted about 54 million years. If I were to fit the entire creation of universe in a year, then the Cambrian Explosion would happen during December 15th. When Cambrian explosion (or radiation, some might say) occurred, vast diversity of animals took place and rapid animal evolution happened, be it aquatic of land. Additionally, many scientists also believed that most animals that existed today originated from the explosion.

The dominant animals that lived during the period was aquatic, given that the Earth was practically ocean and land was hardly to be seen. Trilobites were assumed to be the dominant organisms but after future research, it was proven wrong and replaced with arthropods which was mainly dominant as aquatic organisms. It was later known that trilobites were a small part of arthropods family, which demonstrate their similar structure.

Trilobites – a subgroup of arthropod, source

Many had voiced out their theories as to how the explosion happened but the cause of it is still unknown. Many scientists believe that it was the sudden elevation of oxygen level and concentration of calcium in water that boost the evolution.

The graph showing rise in oxygen level, source

Theories like the environmental and ecological changes on Earth and how lagoons and islands are formed were also debated. The lagoons was said to provided shallow pools as the habitat  to live in and necessary food for the animals, thus creating the rapid appearance of animals. Some other theories claimed to have genetic reasons as to why the explosion happened. There are still many unresolved questions and remarks about the period, and scientists are still muddled as to how the evolution and diversification could have happened in such a short amount of time. Those questions aside, the Cambrian period had definitely marked such an impactful event in the timeline of our universe.