Cuttlefish
Sepiida
Animal Type: Cephalopod
Habitat: Coastal waters & continental shelves
Diet: Carnivore
Relatives: Squid & octopuses
Special Ability: Rapid color and pattern changes
About Cuttlefish
Cuttlefish are marine animals related to squid and octopuses. Although their name contains the word "fish," cuttlefish are not actually fish at all. They are cephalopods, a group of mollusks known for their large brains, flexible bodies, and unusual abilities.
Cuttlefish have eight arms and two longer feeding tentacles. They use these tentacles to quickly grab prey such as small fish, shrimp, crabs, and other crustaceans.
Masters of Camouflage
One of the most amazing things about cuttlefish is their ability to change the appearance of their skin. They can quickly alter their colors, patterns, and even the texture of their bodies.
Special pigment cells called chromatophores help create these changes. Cuttlefish use camouflage to hide from predators, sneak up on prey, and communicate with other cuttlefish.
Their patterns can shift in only moments, allowing them to blend into sand, rocks, coral, and other parts of the seafloor.
Cuttlefish have W-shaped pupils. Their unusual eyes help them see contrast and movement very well, even in dim underwater environments.
The Twilight Zone
Some cuttlefish can be found in waters extending into the Twilight Zone, also called the Mesopelagic Zone. This layer of the ocean lies roughly between 200 and 1,000 meters (656 to 3,280 feet) below the surface.
Only a small amount of sunlight reaches this depth. The water gradually becomes darker and usually colder as you descend.
There is not enough light for photosynthesis to take place throughout most of this zone. Instead, animals depend on food that sinks down from above or on hunting other animals.
Many Twilight Zone animals have special adaptations for living in dim light, including large eyes, sensitive vision, dark coloring, reflective bodies, and bioluminescence.
What Do Cuttlefish Eat?
Cuttlefish are predators. Their diet includes crustaceans, shrimp, crabs, small fish, and sometimes other cephalopods.
When hunting, a cuttlefish may slowly approach its prey while camouflaged. Once close enough, it rapidly shoots out its two long feeding tentacles and pulls the prey toward its mouth.
The Cuttlebone
Inside a cuttlefish is a hard internal structure called a cuttlebone. Unlike an ordinary bone, it contains many tiny chambers filled with gas and liquid.
By changing the amount of liquid inside these chambers, the cuttlefish can control its buoyancy. This helps it rise, sink, or remain at a certain depth without constantly swimming.
How Do Cuttlefish Move?
A fin runs around much of a cuttlefish's body. Gentle waves along this fin allow it to move slowly and carefully through the water.
When it needs to escape quickly, a cuttlefish can use jet propulsion. It pulls water into its body and forcefully pushes it through a tube called a siphon, sending the animal rapidly in the opposite direction.
Ink Defense
Like squid and octopuses, cuttlefish can release ink when threatened. A cloud of dark ink can confuse a predator and give the cuttlefish time to escape.
This defense works together with their camouflage, speed, and ability to rapidly change direction.
Where Are They Found?
Cuttlefish live mainly in the eastern Atlantic, Mediterranean, Indian, and western Pacific Oceans. They are especially common around continental shelves, reefs, sandy bottoms, and seagrass habitats.
Different species prefer different depths. Many live in relatively shallow coastal waters, while others can travel into deeper environments where sunlight becomes much weaker.
A Very Smart Invertebrate
Cuttlefish have relatively large and complex brains for invertebrates. They can learn, remember information, navigate their surroundings, and adjust their behavior in response to different situations.
Their intelligence, strange eyes, color-changing skin, jet propulsion, tentacles, and internal cuttlebone make them one of the ocean's most unusual animals.