When Life Got Complex: The Cambrian Explosion
When Life Got Complex
Many, many years ago, before dinosaurs roamed there was a vast sea full of single-celled creatures and free floating organisms. Until one day, quite out of the blue, a mass diversification of organisms appeared and scientists are still trying to figure out why.
Oxygen Theory
The earliest theory is that the Cambrian explosion was a consequence of many small, complex environmental changes that triggered evolutionary development, including the environment change of a sudden rise of oxygen levels in the ocean. Metabolization with oxygen produces much more efficient energy as animals rely on this controlled combustion to utilize the energy needed for muscle movement, nervous system, the building of hard bone structure like exoskeletons and teeth. The formation of these parts gave us fossils and the proof of the introduced predator- prey relationships. A majority of hard fossils found contain holes from attack that prove predation, as well as addition of animal parts that can be used as tools for burrowing in order to get away from these predators.
Contribution Due to Sea Level Rise
The continued diversification of these organisms sprung from the introduced biological relationship of predator-prey. Organisms had started to build complex body systems in order to protect themselves or to pursue larger prey. Prey’s main form of protection was their exoskeletons. In addition to the increase of oxygen levels in the ocean, the invasion of other chemicals in the ocean provided assistance in the formation of organism’s hard parts. Fossils of organisms with hard skeletal bodies started to appear about 540 million years ago, when there was a major rise in sea level. The rise in sea level washed crucial chemicals like calcium and phosphate into the ocean. The soft body creatures used the chemicals from the sea water to create their shells by combining the chemicals with their soft body tissue to form hard parts, inorganic materials in a process called biomineralization (Figure 1).
Figure 1
Patterns of Movement
The movement of these organisms also encourages ideas of the sophistication of life itself. Scientists have discovered fossils marking the movement patterns during the early Cambrian. They discovered trails with sharp curves and parallel lines that conclude the idea of the evolution of intentional movement by these animals. A study shows the observation of a curvy feeding trail suddenly becoming straight in efforts to evade a possible predator. This brings more evidence to the appearance of predator-prey relationship during this time.
An Evolution
From the explosion, the earth gained the first echinoderms, which starfish and sea urchins are descendents of, brachiopods, and the trilobites (Figure 2), the most iconic of the cambrian fossils. The trilobites were the most commonly found fossil from this time period. A study conducted in Oxford claims that the Cambrian saw the origins and evolution of the largest animal group known to Earth today, the euarthopods. Euarthopods contain insects, spiders, crustaceans, and trilobites, making up 80 percent of animal species population on the planet. Being this large of number, confidently, one can say that they are pretty important to the flow of many earth ecosystems.
Now that you know more about the Cambrian Explosion and the sea creatures birthed from it, I encourage you to explore what some may call the sequel of the Cambrian Explosion, the Great Ordovician Biodiversification Event (GOBE). This events displays more diversification of marine organisms and the start of life on land.
References
“Information about the Cambrian Period.” Science, www.nationalgeographic.com/science/article/cambrian. Accessed 19 Sept. 2024.
Fox, Douglas. “What Sparked the Cambrian Explosion.” Nature, 18 Feb. 2016, pp. 268–270.
Murdock, D. (2020, June 25). Cambrian explosion. More Than A Dodo. https://morethanadodo.com/tag/cambrian-explosion/
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