Of all the hostile mobs in Minecraft, the spider is the one that seems to have the most capabilities. Not only are they smaller than a one block height, they can climb over fences and walls to attack you. They may only spawn in the dark, but spiders in light levels higher than 11 will become neutral and not chase you. Spiders can also pounce towards a player during their attacks, making them difficult to run away from.
|8 full hearts||Neutral in light levels > 11, Hostile in light levels <= 11||Easy: 1 full heart, Normal: 1 full heart, Hard: 1.5 full hearts||0-2 String 33%, 1 Spider eye|
Spiders will spawn when light levels drop at 7 or less. They can spawn on any opaque block and will spawn in groups of 1-4. You may also encounter a dungeon with a spider spawner.
These spiders will spawn much more frequently, but still follow the same rules of light level requirements. You may also find spiders spawning in cobwebs to help fit the explanation of why the cobwebs formed in the first place.
Spiders may spawn in the night, but because they are not undead you may find them wandering aimlessly during the day. They do not burn up like zombies or skeletons, but luckily you do not have to worry about them attacking you while it is daylight out.
Spiders are hostile at light levels at or below 11. This only occurs if the area around them when they first aggro is dark enough. Expect every spider to be hostile at nighttime, but even in daylight there may be dark crevasses where a spider will aggro onto you. Even if the spider is led to a well lit area, they will still chase you as a hostile mob. If you attack a spider that is in broad daylight they will become hostile and begin chasing you regardless of light level.
You may see spiders climbing walls while they are wandering or aggressively chasing you.
This is unique to spiders and they can climb almost any wall. To prevent spiders from climbing over your fences you can place slabs on top of your fences to keep spiders from getting over.
As long as the spider has no other wall to climb over, they will get stuck climbing up the fence and hit their heads on the slabs placed on top of fence blocks.
Spiders will aggressively pounce towards players when they are aggroed. This can make escaping a spider difficult as the pounce sends them forward faster than their regular walk speed.
Spiders in hard mode have a small chance, depending on how long you have been in the area, to spawn with a beneficial buff. They can spawn with swiftness, strength, regeneration, and even invisibility.
Spiders will drop 0-2 pieces of string and have a 1/3 chance of dropping a spider eye. They will also drop five experience when defeated.
In the Bedrock edition, regular spiders can't climb magma blocks. Cave spiders are capable of climbing any block, and it seems odd that only in Bedrock edition that spiders can't climb magma blocks.
A cave spider is smaller than a regular spider, they can fit through 1x1 holes unlike the regular spider. Not only are they smaller, but they can inflict poison damage if they attack you. Cave spiders have all the unique capabilities of regular spiders, but they are simply more dangerous.
A spider checks its surrounding light levels before aggroing onto the player. This can happen in broad daylight if the spider is in a cave or even under some leaves. If you attacked the spider, this is intended behavior as spiders are neutral in light levels above 11. You are not totally safe from spiders during the daytime, if you are trying to prevent a fight, stay away from them even in daylight or expect them to be hostile.