In the Harry Potter universe, the Acromantula is a monstrous spider capable of human speech. It originated in Borneo, where it inhabits dense jungle. Its distinctive features include the thick black hair that covers its body; its legspan, which may reach up to fifteen feet; its pincers, which produce a distinctive clicking sound when the Acromantula is excited or angry; and a venomous secretion. The Acromantula is carnivorous and prefers large prey. It spins dome-shaped webs on the ground. The female is bigger than the male and may lay up to one hundred eggs at a time. Soft and white, these are as large as beach balls. The young hatch in six to eight weeks. Acromantula eggs are defined as Class A Non-Tradeable Goods by the Department for the Regulation and Control of Magical Creatures, meaning that severe penalties are attached to their importation or sale.

This beast is believed to be wizard-bred, possibly intended to guard wizard dwellings or treasure, as is often the case with magically bred monsters. Despite its near-human intelligence, the Acromantula is untrainable and highly dangerous to wizard and Muggle alike. Hagrid was expelled from Hogwarts in his third year for possession of the Acromantula Aragog who was thought by Hogwarts teachers to be the monster in the Chamber of Secrets.

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