Cave Spider

The Cave Spider is a hostile mob using the same model as the Spider, but with a blue skin and smaller size. They can be more dangerous than the regular spider, but in turn they are much rarer than regular Spiders. Cave Spiders do not spawn naturally; they only come from Spawners found in Abandoned Mine Shafts. Their small size (0.7 x 0.7 x 0.5) allows them to fit through spaces one block wide and just half a block tall.

Behavior
Aside from their small size and venom (see below), Cave Spiders inherit most of their behavior from regular Spiders. They can climb walls, jump, 'see' the player through solid blocks, and become neutral in bright light. They are not affected by cobwebs or Splash Potions of Poison.

Venom
The most notable feature of the cave spider is its venomous bite. When bitten by a Cave Spider on any difficulty except Easy, the player's health bar turns yellow-green and gradually decreases. The venom inflicts half of a heart of damage about every second and a half, and lasts for 7 seconds on Normal difficulty, or 15 seconds on Hard. Armor does not prevent venom or reduce the damage received from it. Since 1.9 Pre-Release 4 Jeb gave milk the ability to cure the player of the venom. Regardless of the difficulty, venom cannot kill you, but it can drop your health to dangerously low levels. Venom will affect most mobs the Cave Spider attacks, including Skeletons and Iron Golems, but not other Cave Spiders or Spiders.

History
The Cave Spider was first introduced in the Beta 1.8 Pre-release.

SMP servers upgraded from older versions running in peaceful mode may begin spawning cave spiders, though no other monster appears in the world. This is because in older versions setting the Server.properties key  to   would place the server in peaceful mode. As of Beta 1.8, a separate key  must be set to zero to select peaceful difficulty; setting   to   prevents monsters from spawning randomly in dark areas but does not disable spawners. Because the  key defaults to 1 (easy), servers without the key configured at all changed from running in peaceful mode (prior to Beta 1.8) to easy mode (as of Beta 1.8).

Trivia

 * Cave Spiders are faster than normal spiders.
 * Cave Spiders will leap into an area three blocks high and wait for the player to get close enough to be attacked.
 * They may be able to go through a 1 block gap, but they cannot fit between a fence post and an adjacent block. The most effective method to farm spider eyes is via killing the spiders through the fence gaps; the player can hit them between the gaps with impunity.
 * The Cave Spider's texture appears to be at a higher-resolution than it's normal counterpart - this is because the textures occupy a smaller space.

Bugs

 * Because of the natural tendency of cave spider spawners being created with cobwebs and ceilings, but without walls such as the Moss Stone walls in dungeons, cave spiders can be spawned in the middle of a cavern or a ravine.