Question

The Cambrian explosion a. caused a spectacular increase in the size and complexity of animal life. b. caused a mass extinction. c. was the time during which all living animal phyla suddenly appeared. d. had few consequences for the later evolution of life.

Short answer

c. was the time during which all living animal phyla suddenly appeared.

Step-by-step solution

- Understand the Cambrian Explosion

The Cambrian Explosion refers to a period in the Earth's history approximately 541 million years ago when there was a rapid increase in the diversity and complexity of animal life.

- Analyze Option a

Option a states that the Cambrian explosion caused a spectacular increase in the size and complexity of animal life. This aligns with the known facts as many complex organisms appeared during this period.

- Analyze Option b

Option b states that the Cambrian explosion caused a mass extinction. There is no evidence to suggest that the Cambrian Explosion caused any mass extinction events.

- Analyze Option c

Option c states that the Cambrian Explosion was the time during which all living animal phyla suddenly appeared. This is correct as many major groups of animals first appeared during the Cambrian period.

- Analyze Option d

Option d states that the Cambrian Explosion had few consequences for the later evolution of life. This is incorrect as the event had significant implications for the evolution and diversity of life on Earth.

- Select the Best Answer

Out of options a and c, option c is the most precise and complete description of the Cambrian Explosion. Therefore, the correct answer is c.

Key concepts

animal phyla

The term 'animal phyla' refers to the broad categories into which animals are classified based on their general body plans and other major characteristics. Each phylum represents a unique early evolutionary lineage within the animal kingdom. These categories help scientists understand and study the diversity of animal life. During the Cambrian Explosion, nearly all major animal phyla appeared suddenly. This sudden emergence is what makes this period so extraordinary.
Some of the well-known animal phyla that emerged are:

• Arthropods (insects, spiders, crustaceans)
• Mollusks (squids, clams, snails)
• Chordates (vertebrates, including humans)
• Poriferans (sponges)

This rapid diversification allowed for the wide variety of animal forms we see on Earth today.

evolutionary biology

Evolutionary biology is the study of the processes that have given rise to the diversity of life we see today. This field looks at how species evolve, adapt, and sometimes go extinct over many generations. The Cambrian Explosion is a key focus in evolutionary biology because it marks a time of rapid evolutionary change. Before this period, most organisms were simple and microscopic. However, the Cambrian Explosion saw an incredible increase in both the complexity and size of animals.
Key concepts in evolutionary biology include:

• Natural Selection: The process where organisms better adapted to their environment tend to survive and produce more offspring.
• Mutation: Changes in DNA that can lead to new traits.
• Speciation: The formation of new and distinct species in the course of evolution.

The Cambrian Explosion showcases these concepts vividly, as different animal groups developed new structures and forms that allowed them to thrive in various ecological niches.

mass extinction events

Mass extinction events are periods in Earth's history when a large number of species die out in a relatively short amount of time. Although the Cambrian Explosion itself was not a mass extinction event, it is often contrasted with such events to highlight the rapid increase in biodiversity it produced.
Mass extinctions can be caused by:

• Environmental changes (such as climate shifts)
• Catastrophic events (like asteroid impacts)
• Volcanic eruptions
• Human activities

These events lead to the abrupt loss of vast numbers of species, but they also offer survivors new opportunities to evolve and diversify. Understanding the differences between these extinction events and the explosive diversification during the Cambrian period provides valuable insights into the dynamic nature of life on Earth.

animal diversity

Animal diversity refers to the variety of animal species and their complexities. This concept not only covers the number of species but also their forms, behaviors, and ecological roles. The Cambrian Explosion was a critical time for animal diversity because it resulted in the formation of many new life forms almost simultaneously. This period saw the emergence of complex organisms with specialized features such as eyes, limbs, and different body shapes.
Important aspects of animal diversity include:

• Ecological roles: Different species fulfill various functions in their ecosystems, such as predators, prey, and decomposers.
• Morphological diversity: The variety of physical forms and structures found in animals, such as different types of limbs and sensory organs.
• Behavioral diversity: Differences in how animals behave, communicate, and interact with their environment and each other.

Thanks to the Cambrian Explosion, the foundations for this rich tapestry of life were laid, setting the stage for the biological diversity we value today.