ink sac
cephalopod anatomy
Quick Summary
The ink sac is an organ found in most cephalopods, including octopuses and squids. This sac produces a dark fluid containing melanin, the same pigment found in human hair and skin. When a cephalopod feels threatened, it ejects this ink through a funnel organ as a defense mechanism. The ink creates a visual screen to confuse predators, allowing the cephalopod to escape. Some species' ink can even temporarily paralyze a predator's senses. This ejection is a complex process controlled by the cephalopod's nervous system.123
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