The Den Den Mushi are snails that are used for communication and/or visual aid throughout the world. They are usually seen with phones or fax machines attached to their shells.
They have the ability to communicate with each other telepathically through radio waves. The people of the One Piece world take advantage of this ability by attaching buttons and receivers to them. According to Franky, this process is quite simple, as when he offered to make communicators for the Mink Tribe from the wild snails of Zou. Den Den Mushi thus take the place of telephones and other similar machines in the world of One Piece. They are classified as type "B" creatures, being "Small Friendly".
A "ringing" Den Den Mushi will make a purururu (プルルル?) sound, rendered identically to the real-life Japanese onomatopoeia for old-fashioned phone-rings. However, the anime (which renders the sound closer to purupuru) indicates that the snails are actually pronouncing these "rings" phonetically (and very dryly), rather than making any noise akin to a genuine ring.
During active use, the Den Den Mushi will mimic the speaker's speech and display their emotions as well as take on the distinctive physical traits of the person on the other end. For example, when someone screams, the snail will scream as well. They also seem to be able to change their eye color and even if they lost some teeth (ex. Caesar talking over Law's Den Den Mushi) whenever someone is talking through. Den Den Mushi are usually active when someone answers the phone, but once they are hung up, they go to sleep. It is possible for two Den Den Mushis converse with each other using a third party.
Despite acting like machines, they are actually animals. Since being raised by humans gives them access to plenty of food, Den Den Mushi do not mind being used and tamed. The snails appear to be amphibious, as Fukaboshi was seen using one underwater. However, they do not work in extreme cold. When an S.O.S. signal is sent out, rather than ringing normally as in a regular phone call, the Den Den Mushi cries loudly. When a Den Den Mushi returns to the wild and their receivers are removed, they become a regular snail.
When Oda was asked if the Den Den Mushi have a silent mode and if they can change their ring tone, he confirmed Den Den Mushi do have a "silent" mode. This is normally activated with a simple "shh" and a head nod. However, as they are living creatures they have to be trained to access this ability. The resulting volume depends on the effectiveness of their training and their diet.
Types of Den Den MushiEdit
The Den Den Mushi appear in many varieties, depending on who owns them and who is talking. They are sometimes designed to resemble their user. Marine Den Den Mushi typically have the Marine symbol painted on their faces and/or shells. Despite their varied appearances, there appear to be general categories by which Den Den Mushi are classified.
Communication Related Den Den MushiEdit
Regular Den Den MushiEdit
The most common type of Den Den Mushi (電伝虫 Den-den Mushi?) commonly seen. They are too big to be conveniently carried around, but their signal range is much further than that of a baby. They can also serve as fax machines if the right accessory is attached. They are capable of making long distance calls, and many are large enough to make a worldwide signal. The Marines are shown to often favour these over Babies in field communications due to the range, carrying them around with the help of a shoulder strap.
Baby Den Den MushiEdit
A Baby Den Den Mushi (子電伝虫 Ko Den-den Mushi?) is a fairly small and portable Den Den Mushi, enough to fit in one's palm or even wear like wrist watches. It's good for keeping in contact with fellow comrades in the same area, but incapable of inter-island calls. They can also be used as speakers, in which to broadcast the user's voice throughout the area.
Black Den Den MushiEdit
The Black Den Den Mushi (黒電伝虫 Kuro Den-den Mushi?), Black Transponder Snail in the English versions, is a type of Den Den Mushi used commonly by the Marines, as listening devices or "wiretaps", to intercept calls between pirates or other miscreants. They are actually a different type of species compared to other types of Den Den Mushi. They do not grow as they age and remain a small portable size for the rest of their lives. They enjoy eavesdropping, and dislike communicating with others. Their abilities to intercept can be blocked by their counterpart, the White Den Den Mushi.
White Den Den MushiEdit
The White Den Den Mushi (白電伝虫 Shiro Den-den Mushi?), White Transponder Snail in the English versions, can be attached to other Den Den Mushi. They send out psychic waves that prevent calls from being intercepted; in a way, they are the opposite of the black Den Den Mushi. They are rare and one was first seen used by Monkey D. Dragon to communicate with Emporio Ivankov.
Horned Den Den MushiEdit
The Horned Den Den Mushi (ツノ電伝虫 Tsuno Den-den Mushi?) can jam radio transmissions. The range and period of a transmission jamming caused by this type are unknown. This species was first used by a member of the Fire Tank Pirates before Sanji and Pudding's wedding as part of the Retrieval Team-Fire Tank Alliance's plan to take down Big Mom. After the Whole Cake Chateau collapsed, Mont-d'Or was able to communicate through a Den Den Mushi from Sweet City to the rest of Totto Land, alluding to the jamming disablement.
Visual Related Den Den MushiEdit
Visual Den Den MushiEdit
The Visual Den Den Mushi (映像電伝虫 Eizō Den-den Mushi?) is similar to the Surveillance Den Den Mushi.
The Proko (プロコ Puroko?) is able to receive, project and broadcast what the Cameko sees onto a bigger video screen. It is an older Visual Den Den Mushi. They are able to broadcast their frequencies between two relatively close locations.
The Cameko (カメコ Kameko?) is able to store images and videos. It is a younger Visual Den Den Mushi. While taking a photo, it create flashes of light with its eyes in order to perform flash photography. It has an antenna connected to the shell, that allows him to send signals and live video feeds to their connected Proko.
Surveillance Den Den MushiEdit
The Surveillance Den Den Mushi (監視電伝虫 Kanshi Den-den Mushi?) is a Visual Den Den Mushi used for surveillance. The Cameko are mounted in specific locations around a building. They are all connected to a singular Proko, connected to a machine which produces video feeds to a set of monitors. In the event that the Cameko spots an intruder, it will send a signal to the Proko, which will cause its red eyes to begin flashing in an alternating manner, and make a buzzing noise to alert the security guards watching the monitors.
Self-Propelled Visual Den Den MushiEdit
Shiki has a variant of the Visual Den Den Mushi called the Self-Propelled Visual Den Den Mushi (自走式映像転送電伝虫 Jisō-shiki Eizō Tensō Den-den Mushi?). As the name implies they are able to move and look around. They also appear to be close to the same size as the Proko and have attachments that allow them to project what they can see to a monitor.
Special Den Den MushiEdit
Golden Den Den MushiEdit
The Golden Den Den Mushi (ゴールデン電伝虫 Gōruden Den-den Mushi?) is an extremely rare breed of Den Den Mushi, apparently made of solid gold and completely immobile. Its sole function is to initiate a Buster Call attack; as a result, its only "accessory" is a single button at the apex of its shell, which immediately delivers a signal to the proper receiving line when pressed.
According to Spandam, permission to access a Golden Den Den Mushi can only be granted by Marines of Admiral rank or higher. Only two specimens have been witnessed thus far, both used by Cipher Pol agents:
- Spandine of CP5 used one, supposedly granted by then-Admiral Sengoku, during the Ohara Incident.
- Spandam himself, as director of CP9, accidentally used one (having mistaken it for his personal Baby Den Den Mushi) during the Straw Hat Pirates' invasion of Enies Lobby. His was supposedly granted by then-Admiral Aokiji.
When activated, the Golden Den Den Mushi apparently automatically transmits its location to the receiving line, to guarantee maximum speed of response.
Silver Den Den MushiEdit
The Silver Den Den Mushi (シルバー電伝虫 Shirubā Den-den Mushi?) is a special type of Den Den Mushi, apparently possessing a solid silver shell, that serves as Marineford's receiving line for the Golden Den Den Mushi. Unlike regular Den Den Mushi, it does not appear to transmit any voices, instead generating a loud vibrating sound to alert all nearby Marines that a Buster Call has been ordered.
The specimens receiving both Spandine's and Spandam's Buster Call orders were visibly aged, with white mustaches and beards; it is unknown if this is inherent to the breed, or simply an indication that they have been used much longer than regular Den Den Mushi (or, possibly, that only one specimen exists and is linked to every Golden Den Den Mushi in active service).
Translation and Dub IssuesEdit
Den Den Mushi are derived from the term でんでんむし (Dendenmushi?), an old Tokyo folk-name for snails. While preserving the pronunciation of this term, Oda substituted different kanji to create a new term:
電(Den?), meaning electric (a common component in the words for most electric appliances, telephones ( 電話Denwa?) included)
伝(Den?), meaning communication
虫(Mushi?), meaning insect (the only kanji reflecting the original meaning, snails traditionally being lumped in with insects and most other garden pests)
Most English translations, professional or otherwise, do not attempt any kind of similar pun, and variously call the creatures Transponder Snails, Telesnails, or Snail-o-Phones (or Shock Bugs, in the case of the English localization for One Piece: Unlimited Adventure).
In the 4Kids dubbed anime, the Den Den Mushi do not assume the voices of their users.
- In one of Oda's SBS, a fan asked Oda to apologize to a Den Den Mushi whose receiver was destroyed by Sanji. Oda responded to the fan's question by explaining that Den Den Mushi are actually born naturally without the receivers and buttons commonly seen on them. The people of the One Piece world attach these devices to the snails in order to use the snails' ability to communicate with one another. Breaking these devices attached in truth does not harm the animal at all.
- Some isolated areas do not have access, or choose not to use Den Den Mushi:
- Skypiea is the only location seen where they seem completely absent or unavailable for use. However, Dials, the remains of particular shellfish that live in the White-White Sea, are used constantly by the natives. 
- The Tontatta Kingdom's dwarves release the snail back to the wild.
- Mokomo Dukedom do not have the knowledge on how to turn the wild snails on Zou into communication devices.
- Wano Country uses Smart Tanishi (スマートタニシ Sumāto Tanishi?, literally meaning "Smart River Snail").
- Regular Den Den Mushi living in the wild appear in both One Piece: Unlimited Adventure and Unlimited Cruise as catchable bugs, used for creating items.
- In One Piece: Unlimited Adventure, they are said to communicate with one another using radio waves. During Spandam's Special attack he uses a Den Den Mushi to call authorize an artillery strike.
- Another reference to the fact Den Den Mushi are living creatures can be seen in the Marineford Arc, when Buggy and the rest of his crew were frozen by Aokiji and unfrozen by Akainu's attack, however, the camera Den Den Mushi had yet to be unfrozen, and when it sank in the seawater boiled by Akainu, it became dehydrated as a normal snail would due to the salt content of the ocean. After that, it got extremely scared by Buggy's crew and hid in his shell. It then started crying from joy after Buggy defended the snail, saying it had worked too hard and deserved a break. It then became very happy, loyal, cooperative and grateful to Buggy, following a running gag where Buggy had won favor with people by looking impressive through pure dumb luck.
- In the 1850s, the French Jacques Toussaint Benoit built a contraption known as the Pasilalinic-sympathetic compass also known as "snail telegraph" based on the hypothesis that mating snails form a permanent telepathic link and can be used to send and receive long distance telegrams.
- Snail – Wikipedia article on snails in general
- Telephone – Wikipedia article on the telephone
- Pasilalinic-sympathetic compass – Wikipedia article on a concept similar to Den Den Mushi