Final answer:
The large increase in animal diversity during the Cambrian period can be attributed to a combination of environmental changes, the presence of suitable living spaces, and ecological relationships between species.
Step-by-step explanation:
The large increase in animal diversity during the Cambrian period can be attributed to a combination of factors. One reason is the environmental changes that created a more suitable habitat for animal life, such as rising oxygen levels and increased calcium concentrations in the ocean. Another factor is the presence of an expansive continental shelf with shallow lagoons or pools, providing living space for different types of animals to coexist. Additionally, ecological relationships between species, genetic and developmental reasons, and the evolution of Hox control genes may have contributed to the rapid diversification of animal species during this period.