Spider Jockey

A Spider Jockey is the rare appearance of a spider being ridden by a skeleton. A Spider Jockey possesses the ranged arrow attack of a skeleton plus the vision, agility, melee attack and wall-climbing ability of a spider. The skeleton and spider are treated as separate entities in the game, thus the two creatures attack and take damage individually (i.e. if the spider is killed, the skeleton will continue to attack and move, and vice-versa). A Spider Jockey can spawn above and below ground. However, generally, underground skeleton riders die of suffocation, due to the spider scaling walls, causing the skeleton to have its head raised into the ceiling and suffocate.

Spawning
A spider has a 1% chance to spawn with a skeleton rider. This means that a spider spawner, spawn egg, or the command can very rarely spawn a spider jockey. Spiders spawned using spawn eggs in the Nether have a small chance (0.8%) of a wither skeleton spawning on them. Likewise, due to the fact that 20% of all skeletons spawned in the Nether are ordinary skeletons, a skeleton may be on the spider the other 0.2% of the time.

Uses
The death of a spider jockey offers a potential five-in-one item drop special. Each Jockey, when completely killed, will yield 0-1 spider eyes, 0-2 string, 0-2 bones, 0-2 arrows, 8.5% chance (9.5% with Looting I, 10.5% with Looting II and 11.5% with Looting III) of a bow (it will usually be badly damaged, and may be enchanted), armor which may be enchanted, and if the skeleton spawned wearing a pumpkin or jack o'lantern it may rarely drop it when killed using a tool enchanted with Looting.

Behavior
The spider controls the movement, so a Spider Jockey will wander aimlessly in the day and only pursue the player at night or in dimly lit areas when the spider is hunting. However, the skeleton will turn and fire at the player as soon as it sees them no matter the time of day (although the skeleton will quickly burn in sunlight, leaving the spider unharmed). Because spiders can detect a player through solid blocks (prior to 1.8), Spider Jockeys can ambush unsuspecting players in sufficient darkness. If the skeleton shoots another hostile mob, the mob will focus its attack on the skeleton but not the spider being ridden, even after the skeleton is killed.

Trivia

 * They are one of the few "mobs" that do not have a spawn egg, due to the fact that they are not unique mobs at all, just a stack of two different mobs.
 * A Spider Jockey can kill itself - sometimes the skeleton arrows will injure the spider and other times the spider's pouncing will run the skeleton into its own arrow.
 * A spider jockey can attack two different players in SMP - this is caused by one player damaging one half of the spider jockey and not the other. This usually happens when a player chased by a spider jockey enters a structure that is too narrow for the Spider to crawl through.
 * Spider Jockeys and Chicken Jockeys are the only mobs that cannot travel through portals. Instead it will go through the portal without travelling through it.
 * When a spider jockey rides a minecart, the minecart will automatically accelerate.
 * If the skeleton on the Spider Jockey is shot by another skeleton, it will jump off and leave the spider to engage the skeleton that shot it.
 * In creative mode, it is possible to have only the skeleton attack you, and vice versa (as seen above), due to the fact that they are two different mobs.
 * Sometimes, the spider despawns, and the skeleton remains. However, it is still sitting and cannot be hurt.
 * The skeleton can wear armor, as shown by picture above.
 * It is possible for the Spider to suffocate the Skeleton rider while climbing a wall, or when the spider walks through a hole the skeleton cannot fit through.
 * If you're attacked by a spider and skeleton separately you have a higher chance of survival because they aren't a single mob; therefore a spider jockey deals double damage but apart the two mobs can easily be dispatched.
 * If a spider jockey jumps into water, the skeleton will jump off the spider.

Gallery
Spinnenreiter Jinete arácnido Araignée chevauchée Póklovas Spider Jockey Spinberijder Pajęczy jeździec Скелет-наездник 蜘蛛骑士