Zoan

Zoan is a type of Devil Fruit. This type of fruit allows the user to transform into an animal and animal-human hybrid forms at will.

First Appearance: Chapter 135; Episode 81

Effect
Allows the user to transform into an animal. This fruit provides three forms: the user's natural form, a full animal form, and a hybrid form, combining both original and animal form into an odd bipedal form (usually in a bizarre way where the size is greatly exaggerated). The only hybrid forms that are not bipedal is the Hebi Hebi no Mi series.

Strength
Mainly improves physical abilities and allows the user to use his or her 3 forms to adapt to a situation during a fight to find the form that gives the biggest advantage.

In their hybrid form Zoan users experience enhanced senses, as this form uses a combination of both animals abilities. Skilled Zoans are also capable of using their powers to shape-shift out of harm's way; this is particularly useful, especially when the Zoan's body has been restrained, as Chopper demonstrated so many times (such as Chopper switching from heavy point to brain point). This type of fruit is considered the best for martial arts of the three types of Devil Fruit and is favoured by fighters and warriors alike.

This fruit type is most useful when applied to objects such as guns or swords, giving an otherwise inanimate object life and increasing its value to the owner of the item.

Weakness
They are limited to the capabilities of the animal they are able to transform into. However, in the case of the Human Human fruit (and most likely all cases with the Zoan Devil Fruit types), it is not totally wasted if the species consumes the fruit of the same nature. If a human ate the Human Human fruit, they would become enlightened. Furthermore, inanimate objects animated to life through the use of the Zoan fruits seem to involve certain requirements in order for the owner to acquire their loyalty (for example, Funkfreed, Spandam's sword, has shown the need to feed).

Other information
The name 'Zoan' for these types of Devil Fruit likely comes from the medical term zoanthropy, where the sufferer believes he is suffering from lycanthropy - changing from human to animal form. While most Zoan users can only use the three forms, the Straw Hat Pirate's doctor Tony Tony Chopper can utilize more forms for a given amount of time with the aid of the "Rumble Ball", which he developed. It's unknown if other Zoan users can also be affected by the Rumble Ball since so far only Chopper has eaten it. It was stated by Chopper that carnivorous Zoan are considerably more bloodthirsty than other Zoan, which may be why they're more battle-adept than other Zoan classifications, as the animal they transform into is evolved to hunt and kill. A majority of the Zoan Devil fruits also come in different "models" that result in variations of the animal. For example, the Inu Inu (Dog) Fruit has Jackal, Dachshund, and Wolf models, the Ushi Ushi (Ox) Fruit has Bison and Giraffe models, and the Neko Neko (Cat) Fruit has a Leopard and Cheetah models. There are also Ancient Zoan types, which one can assume to be extinct animals, that are apparently much more rare than regular Zoan Fruits, as mentioned by Apoo.

List of known Zoan Fruit

 * Inu Inu no Mi (Dog) series:
 * Inu Inu no Mi, Model: Jackal (English dub: Mutt Mutt Fruit: Jackal Strike/Dog Dog Fruit: Model Jackel)
 * Inu Inu no Mi, Model: Dachshund (English dub: Mutt Mutt Fruit/Mutt Mutt Fruit, Dachshund Type)
 * Inu Inu no Mi, Model: Wolf
 * Ushi Ushi no Mi (Cow) series:
 * Ushi Ushi no Mi, Model: Bison (English dub: Ox Ox Fruit/Ox Ox Fruit, Bison Model)
 * Ushi Ushi no Mi, Model: Giraffe
 * Neko Neko no Mi (Cat) series:
 * Neko Neko no Mi, Model: Leopard (English dub: Cat Cat Fruit: Model Leopard)
 * Neko Neko no Mi, Model: Cheetah (Filler, existence uncertain)
 * Tori Tori no Mi (Bird) series:
 * Tori Tori no Mi, Model: Falcon (English dub: Tweet Tweet Fruit/Tweet Tweet Fruit, Falcon Type)
 * Hebi Hebi no Mi (Snake) series:
 * Hebi Hebi no Mi, Model: Anaconda
 * Hebi Hebi no Mi, Model: King Cobra
 * Single model series:
 * Hito Hito no Mi (English dub: Human Human Fruit)
 * Mogu Mogu no Mi (English dub: Diggy Diggy Fruit)
 * Uma Uma no Mi (English dub: Horse Horse Fruit)
 * Zou Zou no Mi

Unknown Devil Fruits

 * X. Drake's "ancient-type" Devil Fruit that allows him to take the form of a dinosaur