Sandy comes from the state of Texas, known from the episode of the same name, but she exhibits many characteristics of a cowgirl character by going to every city in Texas. She speaks with a heavy Southern accent and uses typical Southern slang words and phrases, such as "howdy" and "y'all." She is very fond of her homeland and its culture, as most notably seen in the episode "Texas," in which she grows homesick for it and considers leaving Bikini Bottom to return to Texas. In that same episode, she takes great offense at SpongeBob and Patrick's negative insults about Texas and violently attacks them when they continue to insult it.
Sandy is one of the most intelligent and levelheaded characters on the show. She is a multi-talented scientist and inventor and originally came to Bikini Bottom to study sea creatures and their lifestyles. In "Chimps Ahoy," it reveals that she is employed by a trio of chimpanzees from the surface, named Professor Percy, Dr. Marmalade, and Lord Reginald. As an inventor, Sandy is capable of creating extremely advanced devices with ease. Her inventions include a manned space ship, a teleporter, a submarine that can shrink to microscopic size and go inside a person's body (Squidward Tentacles), a robot ("Whatever Happened to SpongeBob?"), and even a Protogenerator 2000 cloning device ("Overbooked").
Sandy is also very athletic and physically fit. She and SpongeBob share a favorite hobby of karate, and frequently fight each other for fun. The karate they use appears to be stylized to fit that of "play karate," as they both mainly fight with chops and kicks in a cartoonish manner. There also appears to be other forms of fighting in the series, most notably in "Karate Island," where three other fish demonstrate unique fighting styles, (which looks more like stylized versions of Kung Fu rather than Karate.)
Sandy also enjoys extreme sports and thrill seeking, which SpongeBob joins her in on occasion, most notably in "Prehibernation Week." Sandy possesses immense strength and is likely the strongest creature in Bikini Bottom. She is often seen at Goo Lagoon lifting weights with Larry the Lobster, of whom she is a good friend and other muscular fish. In "MuscleBob BuffPants," Sandy shows SpongeBob her immense biceps and an intense daily exercise routine. In that same episode, she wins the eighth annual Goo Lagoon Anchor Toss competition, tossing an enormous anchor 510 yards. In various other episodes such as "Karate Island," "Christmas Who?," and "Whelk Attack," Sandy usually tends to briefly, but prominently, display her muscular body.
Sandy is most commonly seen wearing her suit for oxygen when she is outside of her Treedome. The suit is white, and with a yellow patch with an acorn on it. It also has two red, and a blue ring(s) on each sleeve. The suit comes with a big glass dome (but it does not have an oxygen tank) with a pink flower. She also wears boots with one red dot on each side of each boot. When Sandy appears inside the tree dome, she wears purple clothing, primarily a purple bikini top and a purple and green skirt like bottom. In "Someone's in the Kitchen with Sandy," when her fur pelt is off, she wears a purple bra and purple panties.
When she is on her exercise hamster wheel, she can be seen wearing a white hoodie and blue workout sweats.
At night, she wears a nightgown. In "Sandy's Rocket," she wears a light blue nightgown and is shown for a split second until the camera cut to her face. In "Karate Choppers," she wears a lavender nightgown while karate chopping over the phone with SpongeBob. In "Survival of the Idiots," Sandy wears a pink nightgown throughout the episode. In "Overbooked," she wears a purple nightgown while giving a presentation to her colleagues.
Sandy is usually kind and caring for SpongeBob SquarePants and is known to help him out when he's feeling lost as seen in newer episodes, such as "Lost in Bikini Bottom." However, in older episodes, she is shown to be much crazier. For example in "Prehibernation Week," she is shown to be crazier than ever when she forces SpongeBob to play rather dangerous games, thus leaving SpongeBob to run away. She then forced all Bikini Bottomites to search nonstop for days on end looking for him, to the point when they all ran and hid from her just like SpongeBob. Sandy takes full pride in her Texas heritage and shown with her Texan accent. She had a lot of experience there and won't stand any insults or nonsense from anyone who insults it, as shown in "Texas," where she cried several times throughout the episode because she missed her old homeland. SpongeBob and Patrick then made fun of Texas. She was offended by SpongeBob and Patrick mocking Texas, and thus she chased both of them down and brutally attacked Patrick.
She has also been shown to have a strong competitive streak and a high opinion of herself. In "Sandy, SpongeBob, and the Worm," she completely ignores SpongeBob's warnings about the Alaskan Bull Worm and tells him that she is "too Texas tough," only to discover the hard way that the Bull Worm is indeed too much for her to handle. In "Pressure," she continuously brags that land creatures are better than sea creatures and nearly drowns herself in an attempt to "prove" it.
In "Survival of the Idiots," Sandy is shown during her hibernation as an obese, monstrous version of herself (prior to going into hibernation, animals must have tremendous amounts of body fat and energy reserves to survive the winter). SpongeBob and Patrick enter her snow-filled Treedome and disturb her sleep, and the semi-conscious Sandy viciously attacks them, believing them to be "Dirty Dan" and "Pinhead Larry," two outlaws from her dreams.
In "Texas" she chased and tried to beat up SpongeBob and Patrick for "taking the name of Texas in vain."
In "Prehibernation Week," she played very extreme sports games with SpongeBob; he then hides from Sandy, and Sandy forced every last Bikini Bottomite (even Squidward) to look for him.
In "Survival of the Idiots," Sandy beat up SpongeBob and Patrick whenever they woke her up. That may be because they were interrupting her necessary hibernation and she was very cranky. After all, in the video SpongeBob and Patrick watched prior to entering her snow-filled tree dome, she said that hibernating animals don't like to be woken up. She is also extremely mad at SpongeBob and Patrick when they took away her all of her fur and she used them as bikinis.
In "Kenny the Cat," Sandy frequently talks badly about Kenny and accuses him of fraud. Once Kenny is helped by SpongeBob, she reveals in front of all Kenny's fans that Kenny is a fraud, humiliating him. Later in the episode, while Kenny is conversing with SpongeBob on how to regain his celebrity status, Sandy kicks Kenny up to the surface before he can figure out how to be "special" again.
Sandy is smart, athletic and talented and therefore has many skills such as:
Karate: Out of all the characters in the show who practice Karate, Sandy is the best at it; she has green gear.
Science: Sandy has shown to have a vast knowledge of science: several episodes feature her doing experiments, as the series progressed; she did more and more science.
Singing: Sandy is a very good singer; the episode "Texas" was the first time she was shown singing.
Guitar: Sandy has played guitar while singing several times, also, in the episode "Band Geeks," she was the Lead guitarist of the band.
Lasso: Sandy can throw a lasso very easily such as in "Sandy, SpongeBob, and the Worm," and "The Gift of Gum" also, in video games such as "Battle for Bikini Bottom," she has the ability to throw her lasso to catch or even break things that are far away.
Gliding: In "Battle for Bikini Bottom," Sandy can use her lasso to glide.
Bodybuilding and Muscle Growth: In "MuscleBob BuffPants," "Christmas Who?," "Karate Island," and "Whelk Attack," Sandy is shown to have very huge muscles, and seems to get bigger and bigger and bigger each time they are displayed, and growing at almost pure will.
When she was an adult, she joined a company called Treedome Enterprises. This company sent her down to Bikini Bottom to study the under sea life.
In Bikini Bottom, she met SpongeBob SquarePants while she was fighting a clam. She also met Patrick Star the next day when he tried to save SpongeBob who was at Sandy's treedome for tea and SpongeBob was all dried up because there is no water in her treedome. She has also met many other sea creatures since she arrived at Bikini Bottom.
Sandy lives in a huge polyurethane dome, which is known as the "Treedome." It is air-locked and contains no water, making the treedome the only place in Bikini Bottom where Sandy can survive without her suit Its floor is covered in grass, and features a large tree, which contains Sandy's living quarters. The Treedome also humorously includes a giant hamster wheel, among other backyardish things. As seen in the episodes "Survival of the Idiots" and "Bubble Buddy," the dome produces snow during the winter, from which it can be assumed to simulate other weather patterns as well.
As seen in the episode "Wormy," Sandy has many pets residing in her Treedome, including caterpillars, snakes, crickets, mice, and birds, among others.
The company that owns this and many other treedomes is the Tree Dome Enterprises Limited. Its board of directors, a group of chimps, came for an inspection in "Chimps Ahoy." Her old habitat was back home in Texas.
SpongeBob: Sandy first met SpongeBob SquarePants when he saw her wrestling a giant clam and ran down to save her. Since then, Sandy has been one of SpongeBob's best friends, and she enjoys various activities such as karate with him, she also enjoys going to Goo Lagoon with him and lifting weights
Mr. Krabs: Sandy and Mr. Krabs do not really talk to each other; however, there are a few episodes in which they do talk. When they do, they seem to be very nice to each other and they never really fight.
Patrick: Patrick and Sandy have an unusual friendship. When they are seen with SpongeBob, they tend to get along very well. However, Sandy has numerously been annoyed by Patrick's utter stupidity.
Squidward: Sandy and Squidward usually get along, however there are times where Sandy can get annoyed by him. She is also shown to be happy to help him, such as in "Squidtastic Voyage" when she helped him revive his clarinet reed from his throat. Then in "The SpongeBob Movie: Sponge Out of Water" she was seen carrying him to safety when he was almost crushed by skating humans, and letting him ride on her back when they're chasing Burger Beard.
Plankton: Sandy tends to dislike Plankton, such as in "Someone's In The Kitchen With Sandy" when he stole her fur to steal the secret Krabby Patty formula. However, they did get along in "Perfect Chemistry" as she was impressed by his lab and she knew that Plankton was planning to steal the Krabby Patty formula.
Pearl: Sandy and Pearl do not really talk to each other, but in Texas, Pearl wanted Sandy to stay in Bikini Bottom. In "Bubble Troubles," Pearl helps Sandy breathe air, saying "I guess us mammals have to stick together."
Sandy appears in a majority of SpongeBob video games usually as a playable character and sometimes as a major non-playable character.
Operation Krabby Patty - Sandy appears as a playable character in the Right Side version of the Jellyfishing level.
SuperSponge - Sandy makes an appearance as a non-playable character.
Revenge of the Flying Dutchman - In Revenge of the Flying Dutchman she is a non-playable character who is seen in various parts of Bikini Bottom. First, SpongeBob does Karate with her. Then, she needs help clogging up some holes in her treedome and then she needs help getting a beehive out of her tree (SpongeBob thought it was a big acorn). In Downtown Bikini Bottom, she needs help disposing some garbage. She is later hypnotized by the Flying Dutchman and needs to be rescued along with Squidward, Patrick, Gary and Mr. Krabs.
Battle for Bikini Bottom - Sandy appears as one of the three playable characters, the other two being SpongeBob and Patrick, she is first played in Downtown Bikini Bottom. She also fights Robo-Patrick when SpongeBob and Squidward are frozen. She also defeats the Flying Dutchman alone, when he refuses to give them a golden spatula. She is an extremely useful character, as she can do karate and use her lasso to glide after doing a double jump, swing from Texas Trailer Hitches and Tie up robots before they even get close.
Employee of the Month - She helps SpongeBob and Patrick get to Neptune’s Paradise with her Rocket, but when it breaks down, they land in Bottoms Up and it is revealed that she has a friend named Cowfish Craig and knows about Oxygen Springs.
SpongeBob's Atlantis SquarePantis - Sandy appears as one of the seven playable characters, the other six being SpongeBob, Patrick, Squidward, Mr. Krabs, Plankton, and an Atlantean Guard, her special ability is her lasso.
SpongeBob's Truth or Square - Sandy appears as a major non-playable character, one of the levels focuses on meeting Sandy in Tea at the Treedome.
SpongeBob's Boating Bash - Sandy is playable in this game as a starting driver. She is playable in each mode, and has many vocal lines in both the DS and Wii version as well.
Nicktoons Unite! - She helps guide the heroes through some of the first SpongeBob level. At the end of the level, she explains what has happened in Bikini Bottom. She also tells the heroes that they have an agent in Jellyfish Fields (Patrick).
Nicktoons: Battle for Volcano Island - Sandy appears as one of the playable Nicktoons, the others being SpongeBob, Danny Phantom, Patrick, Timmy Turner (along with Wanda and Cosmo) and Sam Manson, this is the only video game where Sandy's Karate Gear appears as an attack.
Oddly (yet somewhat explainable), she is called "Arenita" in the Latin American dub of the series. "Arenita" stands for "little sand" in Spanish, making it a fairly accurate translation.
In the very last shot of "MuscleBob BuffPants," if the viewer looks closely, she has paw pads on the underside of her feet, and is the only episode to show her having them. While, in all other episodes, she just has a beige or brown surface on the bottom of her paws.
In the episode "Scaredy Pants," Sandy dresses as a pet goldfish in a bowl for Halloween (her air helmet being the bowl), which Squidward, ironically, does not understand.
A package of GoGurt featuring Sandy claims she works for a company called "Tree Dome Enterprises Limited."
In Season 1, Sandy has three dots on her suit instead of an acorn. From Season 2 onward, she has her acorn, although in some Season 2 episodes (like "Wormy" and "Prehibernation Week"), it's only the silhouette of an acorn.
Also, season 1 episodes, Sandy's tail is not visible when she is wearing her suit in comparison to later seasons.
Sandy's fur is slightly darker in Season 1 than in the later seasons. Also her face is a slightly different shape.
Sandy is called "Sandra" for the first time in the episode "Patrick SmartPants."
Despite being established as a scientist in later episodes, Sandy is oblivious to the basic fact that sea creatures cannot survive without water in her first appearance. Although, it may be because SpongeBob told her that he likes air not knowing that she meant without water. It is also possible that she thought he was a kitchen sponge, due to his appearance and the fact that kitchen sponges do not need water.
She appeared the most in Season 8, having a total of 17 episode appearances and one short appearance.
In the live-action puppet sequence in the episode "Pressure," Sandy is represented by a toy puppet and appears to be naked aside from her helmet.
In Croatian dub, her name is Luna Frnjau, which doesn't have any connection between her original name.
It is possible that Sandy knows the Krabby Patty Secret Formula prior to the episode "Karate Choppers," but it may be more likely they were making regular sandwiches in the park.