Why are polyploid animals sterile?

1. Meiosis depends on each chromosome pairing with exactly one partner. 2. With three or more sets present, that neat pairing cannot happen. 3. Meiosis therefore cannot proceed normally in a polyploid animal. 4. It instead produces mostly aneuploid daughter cells with unbalanced chromosome numbers. 5. Those cells cannot yield viable zygotes, so the animal is sterile. 6. A few polyploid animals reproduce asexually instead, by an unfertilised egg dividing mitotically. 7. Polyploid plants, by contrast, are common and tend to be larger and more robust. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 13 "Modern Understandings of Inheritance", section 13.2 Chromosomal Basis of Inherited Disorders_