Editing Octopus (section)

===Ink sac===

The [[ink sac]] is located under the digestive gland. A gland attached to the sac produces the [[octopus ink|ink]], and the sac holds it. The sac is close enough to the funnel for the octopus to shoot out the ink with a water jet. As the animal begins to shoot, the ink passes through glands which mix it with mucus and it leaves the funnel as a thick, dark blob which helps the animal to escape from a predator.<ref name=Mather/>{{rp|107}} The main [[pigment]] in the ink is [[melanin]], which gives it its black colour.<ref>{{cite journal |last=Derby |first=C. D. |year=2014 |title=Cephalopod Ink: Production, Chemistry, Functions and Applications |journal=Marine Drugs |volume=12 |issue=5 |pages=2700–2730 |doi=10.3390/md12052700 |pmid=24824020 |pmc=4052311|doi-access=free }}</ref> Cirrate octopuses usually lack the ink sac.<ref name="marinebio"/>