The Titans (巨人 Kyojin) are the main villains of the anime/manga series, Attack on Titan. They are large creatures closely resembling male humans with various deformities such as over- or under-sized heads and limbs. They can range from 3-15 meters tall, with some exceptions (ranging up to 60 meters). Despite their enormous strength and toughness, Titans' bodies are unnaturally light for their size. The Titans appear to have no objectives other than killing and consuming humans, which they do only by instinct, as they do not seem interested in attacking other animals. They survive on sunlight and do not need to eat to survive - they actually lack any digestive organs, forcing them to occasionally regurgitate consumed prey. The Titans possess no visible reproductive organs, thus it is unknown how they keep increasing their numbers. Dead Titans' corpses decay at an extremely fast pace. They have hard skin and regenerative abilities, and can only be killed by causing a deep incision on the back of the neck. This weakness led to the development of the Three Dimensional Maneuver Gear, allowing humans to navigate quickly in a three dimensional space to access the Titans' weak point. The creatures are at numerous points mentioned to have exceptionally high body temperature. As a result, their bodies emit steam when regenerating, decaying or under heavy exertion; the 60-meter Titan's body emits steam constantly. Some humans such as Eren Jaeger, have the unique ability to summon and control a Titan body. While in this form, the human's normal body rests in the weak point at the base of the neck, connected via masses of muscular tissue, indicating a connection between the sentient and feral Titans. Certain Titans are noted to be Deviant-Type (奇行種 Kikō-Shū), acting in a way that is not normal for Titans, such as not eating humans directly but acting in a way to help their fellow Titans.