Final answer:
The five key innovations in animal evolution are tissues, a body plan, various patterns of embryonic development, segmentation, and notochord.
Step-by-step explanation:
The five key innovations in animal evolution include tissues, a body plan, various patterns of embryonic development, segmentation, and notochord.
Tissues are groups of similar cells that have a common embryonic origin and specialize to perform specific functions. For example, muscle tissue contracts to enable movement, while nervous tissue transmits nerve impulses.
A body plan refers to the organization and symmetry of an animal's body. Most animals have a symmetrical body plan, meaning their body parts are balanced along an axis. This can be either radial symmetry or bilateral symmetry.
During embryonic development, cells differentiate into specific groups of tissues or organs. This process is guided by various patterns of embryonic development, such as the formation of germ layers and the establishment of different cell types.
Segmentation is the division of the body into repeating segments or units. This allows for specialization and improved efficiency in different body regions. An example of a segmented animal is an earthworm.
The notochord is a flexible rod-like structure found in some animal embryos. It provides support and serves as a precursor to the backbone in vertebrates.