A pair of giant yellow glands in the squid liver occupy the first half of the visceral sac and are located on both sides of the esophagus. The front end is round and the back end is pointed. A pair of hepatic ducts are backward along both sides of the intestine, and finally the two ducts meet and lead to the blind sac of human stomach. The gland of the upper branch of the hepatic duct is pancreas. The liver can secrete enzymes and input them into the stomach for digestion. The hepatic duct contracts rhythmically and can absorb nutrients from the blind sac and stomach. Therefore, it has the function of storing nutrients. Amylase and protease secreted by the pancreas also enter the stomach. The digested food is absorbed by the blind sac and the residue is discharged from the anus. At the end of the rectum near the anus, there is a catheter, which is connected with a pear-shaped sac-ink sac, which is located at the back end of the visceral mass. It is actually a very developed rectal blind sac. The glands in the capsule can secrete ink and discharge it from the anus through the catheter, which darkens the surrounding seawater, thus hiding from the enemy.