Joltik's size compared to a Beartic. Joltik is next to Beartic's underarm.
At 4 inches (0.1 meters) tall, Joltik is one of the smallest Pokémon in existence. It has four legs tipped with blue, conical feet. Its ovoid body is completely covered in yellow fur, with notable tufts sticking out on each side of its face, just over each eye, and its lower back. Joltik has four blue eyes. The two larger eyes are set relatively far apart on its face, containing black pupils. The two smaller simple eyes are situated between the first pair, slightly higher up on its face. Joltik's mandibles point downward and reside at the bottom of its face, where they closely resemble tufts of hair.
Joltik is too small to generate its own electricity, so it attaches itself to larger Pokémon and feeds off their static electricity. It will also make its way into houses and feed off electricity in electrical sockets. All of the energy it absorbs it stores in an electric pouch on its body. As seen in the anime, Joltik is not especially aggressive, but will defend itself if bothered. It has been demonstrated that if Joltik is unable to find a source of energy, it will be unable to move and in serious danger. Joltik, and its evolution Galvantula, are the only Pokémon that can learnElectroweb by leveling up.
Its Pokédex entries state that it latches onto larger Pokémon to drain their static electricity, so it may be based on a tick. It may also be based on a jumping spider or, like its evolution, a tarantula. Its Electric typing may derive from a recently confirmed hypothesis that spiders exploit electricity in the atmosphere (along with wind) to 'fly' or balloon using their silk. 
Bachuru may be a combination of バチバチ bachibachi (onomatopoeia for electric crackling) and タランチュラ taranchura (tarantula). It may also be a combination of bug and 虫 chū (bug, an alternate reading of mushi).