Squid

Squids are the first water mobs in Minecraft. They are 8-legged passive mobs introduced in the Beta 1.2 update. Squid are found in water of any depth, and drop ink sacks when killed. They spawn on any difficulty and do not attack, akin to the other passive mobs found on land.

Behavior
When moving about, the squid's tentacles open and close making it seem like they are pushing themselves forward. Squids swim around aimlessly. They are unable to swim upwards so they generally sink to the bottom of the water moments after they spawn. They try avoid one block deep bodies of water. If they are in a one block deep body of water, part of their body will stick out of the water. This can be seen here.

When forced onto land, squids become immobile and will eventually suffocate to death. They take fall damage and burn like any other land mob.

Drops

 * 1-3 ink sacks

Trivia

 * It is impossible to pull a squid onto land with a fishing rod.
 * Hitting a squid underwater causes them to rise approximately 1/3 to 1/2 a block.
 * Due to a bug in beta 1.2, squids can end up above water, swimming through the air. The glitch can be seen briefly here.
 * If water is hacked in, Squid can spawn in the Nether