ink sac

noun

1. a large gland in most cephalopods, as the cuttlefish, octopus, and squid, that is near the rectum and ejects ink at predators.

2. a flexible structure containing ink.

Example Sentences

The well-preserved fossil also “shows some evidence of an ink sac,” probably used to squirt out a dark liquid cloak to help to evade predators, just like modern octopuses, said Christopher Whalen, an American Museum of Natural History paleontologist and co-author of the study published Tuesday in the journal Nature Communications.

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It is preserved well enough that its ink sac and fins are readily visible, as is the very sharp-looking tooth stuck just below its head.

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Each one contained a preserved ink sac.

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The fossilized ink sac of an ancient cephalopod—the group of tentacled invertebrates that includes today’s octopi, squid, and cuttlefish—still holds some of the ink pigment, a new study suggests.

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Again, do not puncture the digestive gland or ink sac during this process.

Read more on Scientific American