How Earth's First, Unkillable Animals Saved the World

Summary

640 million years ago, during the Snowball Earth period, Earth was a frozen wasteland. Despite the extreme cold and lack of oxygen, life persisted, and one of the toughest survivors were sponges. These ancient animals, known for their resilience, played a crucial role in shaping the planet’s future. By filtering water and making room for larger photosynthesizers, sponges helped oxygenate the oceans, setting the stage for the explosion of life that followed. Their unique ability to thrive in harsh conditions allowed them to survive multiple mass extinctions, influencing the course of Earth's biological history.

Takeaways

• 😀 640 million years ago, Earth was covered in ice during the Snowball Earth period, with extreme cold temperatures reaching -43°C at the equator and -130°C at the poles.
• 😀 Despite the harsh conditions, life managed to survive, and some of the earliest animals, like sponges, thrived during this time.
• 😀 Sponges are among the most ancient animals on Earth, having evolved over 780 million years ago, and they are incredibly resilient to extreme environmental stress.
• 😀 Sponges can survive freezing temperatures as low as -80°C and can go without food or water for extended periods, even thriving in oxygen-poor environments.
• 😀 Sponges reproduce both sexually and asexually, using a special structure called a gemmule to survive harsh conditions like freezing temperatures and radiation.
• 😀 Sponges helped oxygenate Earth's oceans during Snowball Earth by filtering out plankton, which allowed larger photosynthetic organisms to thrive and increase oxygen levels.
• 😀 The oceans during Snowball Earth likely had very little oxygen, but sponges' feeding behavior helped increase oxygen levels by making room for larger algae.
• 😀 The first solid evidence of sponges dates back to 640 million years ago, through chemical traces found in rocks in Oman linked to Demospongiae sponges.
• 😀 After Snowball Earth, oxygen levels in the oceans increased, leading to the rise of larger and more complex animals, marking the beginning of the Ediacaran Period.
• 😀 Sponges played a crucial role in shaping Earth's ecosystem, making it more hospitable for the evolution of complex animal life, including vertebrates.

Q & A

What was Earth like 640 million years ago during the Snowball Earth period?

Earth was extremely cold during the Snowball Earth period, with temperatures at the equator dropping to as low as negative 43 degrees Celsius and at the poles as low as negative 130 degrees Celsius. The planet was likely covered in ice, making it nearly uninhabitable.

How did sponges manage to survive during the harsh conditions of Snowball Earth?

Sponges survived the extreme cold and challenging conditions by being incredibly resilient. They could endure freezing temperatures of negative 80 degrees Celsius, survive for years without food, and some even live for up to 20,000 years.

What makes sponges unique as animals, and how do they fit into the animal kingdom?

Sponges are unique because they lack organs, yet they are multi-cellular organisms that produce collagen and have tightly joined cells, characteristics of animals. They filter food from water through pores and canals in their bodies.

How do sponges reproduce, and what is the role of gemmules in their survival?

Sponges can reproduce both sexually and asexually. During harsh conditions, they produce gemmules, a bundle of embryonic cells that can survive extreme conditions, including freezing temperatures, high radiation, and even lack of oxygen.

What was the Snowball Earth event, and how many times did it occur?

Snowball Earth refers to periods when the Earth’s surface was nearly completely frozen. It occurred twice: once between 716 million and 680 million years ago, and again between 650 million and 635 million years ago.

Why is the Snowball Earth period sometimes referred to as 'Slushball Earth'?

Some scientists suggest Snowball Earth should be called 'Slushball Earth' because there may have been areas of open ocean, with only thin layers of ice, allowing some light to penetrate and sustain life below the surface.

How did sponges contribute to the survival of life during Snowball Earth, despite the lack of sunlight?

Sponges helped by being able to live in low-oxygen environments, such as the seafloor, and their filter-feeding habits may have facilitated the growth of larger oxygen-producing organisms, helping to oxygenate the oceans.

What role did sponges play in increasing oxygen levels in Earth's oceans?

By feeding on cyanobacteria and other plankton, sponges cleared the way for larger photosynthetic organisms like algae to thrive, which eventually contributed to an increase in oxygen levels in the oceans, helping to oxygenate the environment.

How did the melting of ice during Snowball Earth contribute to the rise of oxygen levels?

As volcanic activity released CO2, temperatures rose and oceans warmed, leading to the melting of ice. The resulting clearer and more oxygen-rich oceans, partly due to the activities of sponges, allowed for more complex life to evolve.

How did sponges influence the evolution of animal life after the Snowball Earth period?

Sponges likely played a crucial role in shaping the planet’s future by oxygenating the oceans and paving the way for the diversification of animal life. By the end of the Snowball Earth period, oxygen levels were sufficient to support larger, more complex animals, including those in the Ediacaran Period.