1. Where Squids and Octopuses Store Their Ink
Both squids and octopuses have a sac inside their bodies where they store ink. When an enemy is about to attack, they release the ink from this sac and spray it out through a part called the "funnel" [1]. The black color of the ink in both animals comes from the same pigment, called melanin [1].
So, both animals use the same pigment. The difference lies not in what the ink is made of, but in how the animals use it to survive.
2. How Sticky Squid Ink Works Like a Decoy
Squid ink is very sticky. When it is released into the water, it forms a solid mass rather than spreading out immediately [1]. When a squid releases its ink, it first creates a spindle-shaped mass that resembles its own body [1].
While the enemy is distracted by this mass, the squid quickly swims away [1]. This strategy is like a ninja’s "clone technique," where a fake version of the body is left behind to confuse the attacker.
Note: Squid ink is sticky. When released into water, it does not spread quickly but stays as a clump.
3. How Octopus Ink Spreads Like a Smokescreen
Octopus ink is less sticky than squid ink. In water, it flows smoothly and spreads out widely [1]. When an octopus releases its ink, it spreads like smoke, hiding the octopus’s shape from the enemy [1].
While the enemy’s view is blocked, the octopus escapes into a nearby hiding place [1]. This is a defensive strategy that relies on confusion and concealment rather than creating a fake body.
Note: Octopus ink is thinner and spreads more easily in water than squid ink.
4. Why Squids and Octopuses Use Their Ink Differently
The difference in ink strategy comes from how squids and octopuses live. Many squids live by swimming quickly through the middle layers of the sea. Because they are fast swimmers, they can dart away while the enemy is distracted by the ink decoy.
On the other hand, many octopuses live hidden in the shadows of rocks or in crevices. They are better at hiding their bodies and escaping into cover than at swimming quickly. This lifestyle suits the spreading "smokescreen" ink better.
However, this is not a rule for every species. There are octopus relatives that live by swimming in the open ocean, and there are squid relatives that live near the sea floor. Therefore, the tendency does not apply to all kinds of animals [2].
5. How You Can Observe Squids and Octopuses Yourself
If you want to learn more about squids and octopuses, you can try observing them yourself. At an aquarium, watch how their bodies move. You will often see squids swimming smoothly, while octopuses move by crawling between rocks.
If you see a whole squid at the supermarket, look for the ink sac with an adult. Try to find where it is located and what shape it is.
Safety note: Always check squid ink sacs with an adult.
Writing down one word that interests you can help you start your research. For example, you might ask: "Why is there squid ink pasta, but few dishes use octopus ink?" That question alone is a good starting point.