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Cuttlefish Information for Kids

| Updated November 01, 2017

Despite its name, the cuttlefish is not actually a fish. The cuttlefish is a mollusk and is more closely related to the octopus and squid than to any fish. The cuttlefish's unique physical characteristics make it an interesting pet but having experience keeping a saltwater aquarium will make caring for one of these creatures easier.

Cuttlefish Background

In nature, cuttlefish live in marine environments, such as seas and oceans. They are classified as cephalopods, a type of mollusk that moves fast and is smart. Squid, octopuses and chambered nautiluses are also cephalopods. More than 800 living types of cephalopods have been found; 120 of those are kinds of cuttlefish. Cuttlefish can be found in waters throughout most of the world, but none live in the waters around the United States and Canada.

The Cuttlefish Body

Like its cousin the octopus, the cuttlefish has eight arms. Those arms are used for grabbing and holding food, such as crabs. Cuttlefish can move their arms in wavelike gestures to bring its food close enough to grab. Cuttlefish also have three hearts. Two of these hearts keep blood pumping to its gills, which are used for breathing, while the third makes sure blood is going through its whole body. Cuttlefish also have large brains considering the small size of their bodies. Not only are their brains large, but they are also ring-shaped. These large brains help them understand what is going on around them. They can even "hear" sound because sound waves put pressure on thousands of little hairs on their body.

Cuttlefish Ink and Camouflage

Like their cousins, cuttlefish shoot out ink to help them escape danger. Their bodies contain an ink sac that releases the ink when the cuttlefish gets nervous. The ink can be released in clouds so the enemy cannot follow the cuttlefish as it gets away, or the ink can shoot out in small blobs about the same size as the cuttlefish so the enemy becomes confused.

Cuttlefish can change color to blend into the background, avoid enemies and grab food more easily. Their color-changing ability happens because of three types of structures known as leucophores, chromatophores and iridophores in their skin. Each structure contains ink of different colors. The cuttlefish can change the size of these structures to make his skin change color. Cuttlefish can even change the patterns and texture of his skin.

Floating Cuttlefish

Cuttlefish contain a cuttlebone, which is a shell in their body filled with gas. If the cuttlefish increases the gas in its cuttlebone, it will sink lower in the water. If the cuttlefish wants to rise in the water, it releases some of the gas. When the cuttlefish is happy with its location in the water, it keeps the gas levels the same. As a result, the cuttlefish will seem to be floating in the water like a hummingbird seems to float in midair.

Cuttlefish as Pets

In some parts of the world, cuttlefish can be easy to find and keep as pets. People in the United States, however, do not live near cuttlefish habitats so getting one to keep as a pet is more difficult. Some people in the U.S. buy them from people in other countries and have them shipped over. Typically, those cuttlefish only live a few weeks. Pet cuttlefish and wild cuttlefish can live one to three years.

If you keep a cuttlefish as a pet, you need to make sure the aquarium has a good filter. These creatures can get sick easily if too much metal, especially copper, is in their water. The gravel also needs to be kept very clean, and the water needs to be watched carefully. These are all reasons why having experience with aquariums before trying to keep a cuttlefish is a good idea. You should have the aquarium up and running a few months before you add your cuttlefish to the water. However, you need to know what type of cuttlefish you plan to get because the aquarium size you need and water temperature you want are different for different kinds of cuttlefish.

Food is also important for cuttlefish. You can feed it frozen shrimp, crab, mussels, squid and lobster. If you can get living shrimp or crab, your cuttlefish will be even happier.


  • Cuttlefish eat other fish and sea life. Do not keep cuttlefish in an aquarium with other fish or crabs.