Final answer:
Vertebrate animals are considered adults when they can reproduce, are fully grown, and start producing egg cells.
Step-by-step explanation:
Vertebrate animals are adults when:
- They can reproduce: Vertebrate animals reach adulthood when they have the ability to reproduce and produce offspring. This is an important milestone in their life cycle.
- They are fully grown: Another indicator of adulthood in vertebrate animals is reaching their full physical size and maturity. This includes skeletal development, muscle growth, and overall physical appearance.
- They start producing egg cells: In female vertebrate animals, the production of egg cells, or oocytes, is a sign of sexual maturity and can signal adulthood.
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