octopus
Ink sacs can be combined with wool to make black wool. They can also be combined with 1x Bonemeal to make grey dye, and 2x Bonemeal to make light grey dye. You can also use an ink sac on a sheep to dye it black, meaning all wool shorn from it will be black.
You can find ink sacs by killing squids in Minecraft. They can also be found as junk items in fishing.
Currently the only use for ink sacs on Minecraft is for dying wool. Using a raw ink sac on wool turns the wool into black wool. Using the ink sac with one bone meal creates gray dye and using it with two bone meal makes light gray dye.
Cuttlefish produce a brownish-colored ink called sepia. Cuttlefish ink was in fact where sepia first came from. The Latin name of the common cuttlefish, Sepia officinalis, reflects this fact.
Ink Sacs can be used to dye anything that has colour variants - leather armour, blocks of clay, blocks of wool and stained glass windows.
Squid
it is just called an ink well.
By squirting their ink at the other creature.
It is called ink bleed or ink spreading. When ink comes into contact with water, it can spread and create a blurred effect on paper.
A squid
yes it can. its called ink poisoning
because ink is have one phase it called(homogeneous)