Final answer:
The five key innovations in animal evolution include the development of tissues, body symmetry, patterns of embryonic development, segmentation, and development of a coelom or body cavity.
Step-by-step explanation:
The five key innovations in animal evolution are tissues, a body symmetry, various patterns of embryonic development, segmentation, and the presence of a coelom or body cavity. These innovations represent significant stages in the complexity of organisms and have played a crucial role in the diversification of animal life.
Tissues are collections of similar cells that arise from a common embryonic origin and differentiate to perform specialized functions. There are four main types: nervous, muscle, connective, and epithelial. Animals exhibit different body symmetries, such as radial and bilateral, which is a major feature in animal classification. Embryonic development patterns, including the arrangement and differentiation of the germ layers, are essential in determining an organism's final body plan. Segmentation refers to the division of an animal's body into repetitive segments, leading to more complex and flexible body structures. Lastly, the evolution of a coelom, an internal body cavity, allows for the development of more complex organs and organ systems.