Tank is a giant tarantula and the secondary antagonist in the comedy/horror film, Eight Legged Freaks.
Like it's fellow spiders in Joshua's spider farm, it is exposed to noxious chemicals from mutated crickets that Joshua feed to them that causes it to grow even bigger than a man as well as enhances it's intelligence.
It is possible that Tank was the very same tarantula that was seen at the beginning of the film where it successfully break free from it's cage and bit Joshua, causing him to knock down the other spider cages and freeing them.
After the chaos that it caused, it escaped to the nearby mine. When he was fully grown along with his fellow mutated spiders, he is shown to be the biggest spider in the film aside Consuela and became her right-hand General.
During the spider invasion, Tank is one of the spiders that attacks the town. Attracted by Sam, Chris, and Harley's conversazation inside, it moves to knocks down Harlan's trailer. However, due to Pete's interference, it flipped itself it's back by accident as it managed to flip Harley's truck, though it quickly gets to it's feet. He jumps on the car and enraged, but is unable to catch it and the humans escape while it's minions pursue them.
Soon after, it appeared with all the other spiders and prompt them to moves away to do the job as they unable to break through the mall's fortified door. Harlan remembers it as the one who busted up his trailer, and assumes it is the leader due due to it prompts it's minion to move away (this is not right though; it is Consuela who is the leader while Tank himself is following her orders during the invasion). It then break through the steel gate and eventually able to created a huge hole that only fit for half of it's body. Shocked by all humans that armed themselves in front of it, it retracts itself and rally the whole spiders to attack with minor casualities.
It's legs are later seen pushing a tracter that the humans were using to block the spiders away, and then the smaller spiders chase after the humans back to their lair, as the path that humans blocked was turned out another passageway back to their lair. Though knows that humans has trespasses their lair, it remain behind while had the rest of it's minion to search the mall.
At the end of the movie, Tank is killed along with the other spiders in the explosion in the mall.