Jellyfish are gelatinous, free-swimming creatures common throughout all oceans of the world. They can have any number of spots and appear in hives much like bees. They make jelly, in a similar manner to bees making honey. They can also sting like bees. However, unlike bees, they use electric tentacles to shock intruders.
In the series, Jellyfish are portrayed in a stereotypically cartoonish manner and are typically pink in color, but remain physically similar to their real world counterparts.They are very small compared to main characters, approximately the size of a Krabby Patty, though the sizes are inconsistent at times. Since Bikini Bottomites are stated to be only smaller than a human’s foot shown in The SpongeBob SquarePants Movie, this would make jellyfish almost microscopic.
In the same manner as snails are likened to cats and worms are likened to dogs, jellyfish display many qualities of bees, even making a constant buzzing sound whenever they are present. They have been shown living in hives in "Jellyfish Jam". Jellyfish produce Jellyfish Jelly similarly like how bees produce honey. However their jelly is mostly stored within their own bodies with some excess jelly left in their hive. Jelly can be extracted commonly by milking or even making them sneeze. Jellyfish can also squirt their own jelly at will, usually to annoy or insult their target. Excessive loss of jelly causes them to lose their form, thus only a small quantity of jelly is taken at a time. A quart sized jar of jelly seems to be the safest amount of jelly taken from a single jellyfish without causing them harm. The color of the jellyfish also reflects the color of jelly that they will produce, though the exact flavor has never been stated. Nevertheless, Jellyfish jelly is extremely delicious.
Jellyfish's have potent stingers which can cause small painful sores when threatened, hurt, or annoyed, usually through direct contact of their stingers or sometimes short range static zaps. Characters in the series have been stung by them usually for comical effect. Enough stings in a small window of time can be mildly discomforting or even life threatening. One jellyfish in particular, Big Lenny, is known to have fatal stings. However, SpongeBob has been shown grabbing their stingers without any hand protection and walking away without any stings, signifying that the jellyfish can choose when they want to sting someone. An ointment has been developed to alleviate jellyfish stings and is incredibly fast acting.
Jellyfish Fields, a major location in the SpongeBob SquarePants universe, is home to over 10 million jellyfish, according to what has been seen in "Jellyfish Hunter." However, some may drift into Bikini Bottom, but are seldom a nuisance to its denizens. The hunting and catching of jellyfish, known as Jellyfishing, is a popular hobby among sea folk, most notably SpongeBob and Patrick. It is similar to butterfly catching and is typically done only for fun/sport, with the jellyfish being released unharmed. Jellyfish appear in almost all SpongeBob video games, typically as basic enemies or background add-ons. They are usually caught using Jellyfish Nets or jars. They sometimes spook the Bikini Bottomites, but never try to hurt them, unless in self-defense.
They are in tune with nature and have great rhythm. They are often displayed having typical sentience of wild animals though some have shown specialized knowledge including the ability to open windows, operate electronic music equipment, utilize a pay phone, and imitate walking on the ground. Most jellyfish tend to float whimsically and aimlessly, but they can move incredibly fast and controlled, especially as a swarm, to chase down someone. At least 10 Jellyfish collectively can carry SpongeBob into the sky. Spongebob in particular is extremely fond of the creatures and never tries to intentionally hurt them. Likewise, most jellyfish see SpongeBob as a friend as they comforted him when his dreams of flying were crushed and later calling on his aid to stop the construction of a highway that would have gone through Jellyfish Fields.
Pink Jellyfish - The most common jellyfish, pink in color, usually with 3 or 8 spots depending on its size.
Blue Jellyfish - A very rare kind of jellyfish, blue in color, with amazing speed and stealth that makes them pretty hard to catch. In "Revenge of the Flying Dutchman", one is seen moving in a circle. In "Battle for Bikini Bottom", they have 2 health points rather than 1. On the show, one appears in the episode "Jellyfish Hunter" and is called "No-Name" by SpongeBob until the end, where it is renamed "Friend." It also told SpongeBob to "bring it on" earlier in the episode, marking the first time a jellyfish has "spoken".
Ghost Jellyfish - A very legendary kind of jellyfish, poison-green in color, with a ghostly appearance, crimson red spots and some orange streak. In "SpongeBob's Atlantis SquarePantis", ghost jellyfish are the primary targets of the Jellyfish Shooter minigame and if the player does absolutely nothing without pausing, one of them will appear. On the show , one appears in the episode "Scaredy Pants" as a Halloween decoration.
Yellow Jellyfish - A very rare kind of jellyfish, yellow in color, with a quick sting when one comes across them. In "Revenge of the Flying Dutchman",
Green Jellyfish - A very rare kind of jellyfish, green in color, with amazing height-bearing flight that makes them pretty high from defeat. In "Revenge of the Flying Dutchman" and the DS version of "SpongeBob's Atlantis SquarePantis", they are seen in many levels, including the Bikini Bottom main hub, Jellyfish Fields, the Volcano of Mu and the underground cave of the Amulet.
Black Jellyfish - A very rare kind of jellyfish, black in color, with a unique dark appearance and blue spots. In the DS version of "SpongeBob's Atlantis SquarePantis", they are only seen flying in the haunted ship.
Steel Jellyfish - A very rare kind of jellyfish made entirely of steel that are actually easy to defeat, despite their tough appearance. In the DS version of "SpongeBob's Atlantis SquarePantis", they are only seen in Atlantis.
Diamond Jellyfish - A very rare kind of jellyfish made entirely of diamond and can't be defeated. In the DS version of "SpongeBob's Atlantis SquarePantis", they are only seen in the the diamond stage at the Reef of Mu.
Magma Jellyfish - A very rare kind of jellyfish made entirely of magma that gets bigger when hit, making them extremely hard to defeat. In the DS version of "SpongeBob's Atlantis SquarePantis", they are only seen in the magma stage at the Volcano of Mu.
Red Jellyfish - A very rare kind of jellyfish, red in color, that will hurt if touched. In the online game "Gift Lift", they are seen in easy levels as small, but in hard levels as huge.
Gray Jellyfish - A very rare kind of jellyfish, gray in color, that squirts black jelly when touched. They are the only jellyfish that appear in "Picture Day Disaster" online game.
No name/Friend - A mysterious blue jellyfish that appears in "Jellyfish Hunter". Named so because he was the only jellyfish in Jellyfish Fields who SpongeBob has never been able to catch and give a name to. He later helps SpongeBob stop Mr. Krabs, and is renamed "Friend".
Big Lenny - An enormous and dangerous jellyfish whose stings are almost always fatal. The only person known to have survived one is named Doctor Manowar, who has a gigantic swelling on the side of his head as a result. This swelling only hurts when someone touches it. Big Lenny could be a Man O War or a box jellyfish as their stings are known to kill people. Big Lenny is seen in "I'm Your Biggest Fanatic" as a picture and in the PC game "Operation Krabby Patty" during the jellyfishing game.
Jamming Jellyfish- A jellyfish that SpongeBob brings home as a pet in "Jellyfish Jam." SpongeBob and the jellyfish have a disco party. It then invites hundreds of other jellyfish to SpongeBob's house, which they invade and throw a massive dance party in.