What is the ink sac in a squid used for?

Related questions

1. Do you say octopuses or octopi?
2. Can octopus ink kill you?
3. Do octopuses fart?
4. What is takoyaki made of?
5. Do boiled octopus feel pain?
6. Do octopuses eat their own arms?
7. Why do black widows eat their husbands?
8. Is octopus ink poop?
9. Why octopi is wrong?
10. Are elephants smart?

Tags

1. #confuse
2. #nocturnal
3. #cephalopods
4. #predators
5. #light
6. #coleoidea
7. #order
8. #octopus
9. #exception
10. #conditions
11. #water
12. #expel
13. #squid
14. #cuttlefish
15. #which
16. #dwell
17. #cloud