how many limbs do they have?
Eight
Octopus
 The two rear appendages are generally used to walk on the sea floor, while the other six are used to forage for food; hence some biologists refer to the animals as having six "arms" and two "legs"
what group of animals do octopus belong to Molluscs how big do they grow? Adults usually weigh around 15 kg (33 lb), with an arm span of up to 4.3 m (14 ft).
wiki:25676233
Octopus [SEP] External characteristics
The octopus is bilaterally symmetrical along its dorso-ventral axis; the head and foot are at one end of an elongated body and function as the anterior (front) of the animal. The head includes the mouth and brain. The foot has evolved into a set of flexible, prehensile appendages, known as "arms", that surround the mouth and are attached to each other near their base by a webbed structure. The arms can be described based on side and sequence position (such as L1, R1, L2, R2) and divided into four pairs. The two rear appendages are generally used to walk on the sea floor, while the other six are used to forage for food; hence some biologists refer to the animals as having six "arms" and two "legs".