"That's not a rat," croaked Sirius Black suddenly (PA17)
Rats are medium-sized, long-tailed rodents, sometimes kept as pets, but often regarded as vermin or pests.
For sale in the Magical Menagerie on Diagon Alley was a cage full of black rats which were busy jumping rope with their tails; the saleswitch implied that they would live longer than a common rat’s three-year lifespan (PA4).
Several different rat parts are used as potion ingredients, including rat tails and rat spleens.
According to the letter Harry receives in Philosopher's Stone, rats are not on the list of approved list of pets first years are permitted to bring to school, yet students seem to bring them in spite- or perhaps, in defiance of, the rules.
From the Web
Writing by J K Rowling on WizardingWorld (Pottermore): Familiars
- What If an Owl, Rat, Cat, or Toad Just Doesn’t Do It for You?
- Dragons, Boggarts, and Ghosts: The Vital Intel Pettigrew Gained While He Was a Rat
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