Acromantulas are sometimes thought to be giant spiders. This is a mistake. Acromantulas are descended from spiders, yes, but only after centuries of evolution and magical tampering. As a result, they are extremely intelligent and cunning. DO NOT ATTEMPT TO ATTACK AN ACROMANTULA, as they are very physically powerful: Their venom contains a mixture of draughts unmatched by any potion or poison. For this reason, acromantula venom is extremely valuable, though rare. They grow to be about eight feet tall, and are very strong. If a male and female get the slightest opportunity, they will reproduce at an alarming rate. This causes acromantulas to establish colonies very quickly.

Acromantulas usually live in colonies. The leaders are usually the parents, or parent. The colony does not provide expressly for its leader unless the leader cannot take care of themselves. However, as acromantulas grow older, they need less and less food. They live very long. A 142-year-old acromantula was discovered to go eighteen years without food. 

Acromantulas are thought to be vicious and ruthless creatures. This is not true. On the contrary, they are very loyal; an acromantula who owes anything to anyone will repay the debt as they see fit, and the colony leader is not leader after killing its predecessor. Once a leader dies naturally, the wisest acromantula in the colony takes its place.