Cuttlefish are super smart, even though they don't have a backbone. Among invertebrates, they have bigger brains compared to their body. They can change the colors and patterns on their skin in an instant. It helps them talk to each other and hide from danger in the water. We can learn more about these amazing creatures by getting into cuttlefish facts.
17 Interesting Facts About Cuttlefish
1. Cuttlefish are cephalopods.
As a part of the marine mollusk family, cuttlefish belong to the cephalopod classification (head-footed invertebrates) alongside squids, octopuses, and nautiluses. They have soft, elongated bodies, large heads, and big, widely-spaced eyes. They have ten tentacles, two longer than the others, for capturing prey.
On average, cuttlefish can grow to about 15 to 45 centimeters (6 to 18 inches) in length, depending on the species. Their weight varies according to size, but most species weigh between 1 and 3 kilograms (2.2 to 6.6 pounds). Cuttlefish are found in oceans worldwide, primarily in shallow coastal waters.
2. There are more than 100 unique species of cuttlefish.
There are more than 100 species of cuttlefish inhabiting tropical and temperate waters across a wide range of habitats, including shallow coastal areas and deeper ocean floors. One of the most notable is the common cuttlefish (Sepia officinalis). This species is one of the most well-known cuttlefish in coastal waters across the Mediterranean Sea and the northeastern Atlantic Ocean.
Flamboyant Cuttlefish (Metasepia pfefferi) is renowned for its vibrant and flashy color patterns, including pink, red, and purple hues. It is found in Indonesia, Malaysia, and the Philippines and is relatively small compared to other cuttlefish species.
On the other hand, Pharaoh Cuttlefish (Sepia pharaonis) lives in the Indo-Pacific region, ranging from the Red Sea to the western Pacific Ocean. It is named after the ancient Egyptian Pharaohs and is known for its distinctive black-and-white stripe pattern along its body.
Meanwhile, The Broadclub Cuttlefish (Sepia latimanus), stands out within the cuttlefish family due to its notable size and the distinctive club-like shape of its two extended feeding tentacles.
3. Giant Australian Cuttlefish is the largest species.
The Australian Giant Cuttlefish is the largest cuttlefish species known3. They can grow up to one meter long and weigh around 10 kilograms or more. Despite their impressive size and intelligence, cuttlefish have a relatively short life expectancy of one to two years.
4. Cuttlefish have three hearts.
One fascinating fact about cuttlefish is that they have three hearts that help them pump blood in their bodies2. Their first two hearts are called "branchial hearts." Their primary function is to pump deoxygenated blood from the body to the cuttlefish's large gills. The third heart, known as the "systemic heart," circulates oxygenated blood throughout the cuttlefish's body.
5. They prefer to live in areas with good hiding spots.
Cuttlefish prefer to inhabit places with hiding spots like reefs and seagrass beds, allowing them to use their camouflage and mimicry skills. Cuttlefish can change where they live and what they eat depending on the environment and food availability. They can adapt to different conditions like water temperature and saltiness. Some stay in one place, while others move around during their lives.
6. Their favorite food is shrimp.
Cuttlefish are skilled hunters1, and their diet mainly includes tiny shrimp, crustaceans, and small fish found in their habitat. They have a strong preference for shrimps. Furthermore, they have a unique way of capturing their prey - using their quick color-changing abilities and stealthy approach to get close before striking with their two tentacles.
They can also eat crabs and other small crustaceans, thanks to their specialized beak-like mouth that helps them crush the hard shells of these creatures. Cuttlefish eat other invertebrates like tiny worms, mollusks, and even cuttlefish eggs. Baby cuttlefish tend to eat primarily small shrimps.
Related read: Types of shrimps.
7. Their skin can change color for survival reasons.
Did you know that cuttlefish have a unique ability to change their colors? This is achieved through specialized cells called chromatophores located in their skin. These cells contain pigments of different colors, such as red, yellow, brown, and black. The cuttlefish can contract or expand these cells using muscular control to selectively reveal or hide specific colors, creating intricate patterns on their skin.
Cuttlefish also have iridophores and leucophores, which contribute to their color-changing abilities. Iridophores reflect light and produce iridescent colors, while leucophores scatter light to create a silvery or white appearance.
To enhance their camouflage abilities, cuttlefish can rapidly change their skin color and texture to blend seamlessly with their surroundings. They use specialized muscle fibers called papillae to manipulate the texture of their skin, creating tiny bumps and ridges or even mimicking the appearance of objects in their environment, effectively concealing themselves from predators or prey.
Cuttlefish also use their color-changing abilities for communication and social signaling. For example, the common cuttlefish (Sepia officinalis) can display moving zebra stripes over their bodies and arms, a fascinating aspect of their camouflage and communication strategies.
Check out another creature that can change its color at will. Read our chameleon facts.
8. Cuttlefish are brilliant.
Their intelligence is one of the most astonishing cuttlefish facts. Studies have shown that cuttlefish are capable of learning and remembering tasks. A study published in the journal "Current Biology" in 2003 demonstrated that cuttlefish can learn to associate different visual cues with rewards and remember the associations over an extended period. This ability indicates a level of cognitive flexibility and memory retention in cuttlefish.
Cuttlefish have also demonstrated self-control abilities, which further highlight their intelligence. In a study published in the journal "Proceedings of the Royal Society B" in 2009, researchers tested self-control in common cuttlefish using a delay of gratification task.
In the experiment, cuttlefish were given a choice between immediate access to food (a less preferred, smaller piece of shrimp) and waiting for a short period to receive a larger, more preferred piece of shrimp. The cuttlefish showed remarkable self-control by consistently waiting for the larger reward rather than immediately consuming the smaller one4.
9. Cuttlefish swim through jet propulsion and fin movements.
Cuttlefish are skilled swimmers, employing jet propulsion and fin movements to move through water with remarkable agility. Their primary swimming mode is through jet propulsion, where they rapidly contract their mantle cavity muscles to expel water through a funnel-shaped siphon. This forceful expulsion propels them in the opposite direction, and they can alter the siphon's direction to steer and change their swimming path.
Cuttlefish also use their lateral fins and smaller head fins as stabilizers, assisting in adjusting their position and direction while swimming. This combination of techniques enables cuttlefish to navigate their marine habitats precisely, making them effective predators and skilled hunters.
10. Male cuttlefish use elaborate skin patterns during mating.
Smaller male cuttlefish exhibit a fascinating and strategic behavior called "mate deception" or "sexual mimicry" during mating season. In certain species of cuttlefish, males employ a clever tactic of disguising themselves as females to gain a competitive edge during mating encounters.
On the other end, the male cuttlefish will show an elaborate and flashy display of color patterns to attract female cuttlefish. Males may compete to attract mates, forming spawning aggregations. Males transfer sperm packets using a specialized arm called the hectocotylus into the female's mantle cavity. And females can copulate with multiple males.
11. They only reproduce once in their lifetime.
Did you know that cuttlefish have a unique reproductive strategy called semelparity? This means they only reproduce once in their lifetime, an uncommon behavior among other cephalopods that can reproduce multiple times. Reproduction is a significant energy investment for cuttlefish, a crucial event in their lives.
Once female cuttlefish mate, they lay their eggs on the seafloor or attach them to structures underwater, like rocks or vegetation. The eggs are usually in clusters or strings and have a gelatinous coating that protects them from predators and environmental stress.
The female cuttlefish guards and cares for the eggs until they hatch. After hatching, the parent cuttlefish sadly die, and the cycle starts again. Young cuttlefish reach sexual maturity at 14 to 18 months old and have a lifespan of just 1 to 2 years.
12. Cuttlefish have blue-green blood.
Cuttlefish blood is uniquely greenish because of a component called hemocyanin. Hemocyanin serves a similar purpose to hemoglobin found in the blood of vertebrates, like humans, but with a difference. While humans use hemoglobin to carry oxygen, cuttlefish use hemocyanin to disperse oxygen.
The hemoglobin in vertebrates contains iron, giving the blood a red color when it carries oxygen. On the other hand, hemocyanin in cuttlefish and other cephalopods contains copper, resulting in a greenish-blue color when it carries oxygen.
13. They have a fantastic vision.
The eyes of cuttlefish are highly sophisticated and well-adapted to their underwater environment. Cuttlefish have large and prominent eyes on the sides of their head, providing them with a wide field of vision. Their eyes are similar to those of humans in that they contain a cornea, lens, and retina. However, the structure and design of cuttlefish eyes allow them to excel in underwater vision.
One unique feature of cuttlefish eyes is the W-shaped pupils, distinguishing them from the round pupils of many other animals. This distinctive pupil shape helps cuttlefish manage the light entering their eyes, making them efficient at adjusting to different light conditions underwater.
Cuttlefish can also detect polarized light. They have specialized cells called photoreceptors that enable them to perceive a broad spectrum of colors. This enhanced color vision is essential for communication, camouflage, and identifying predators. Interestingly, it also helps them find prey like silvery fish whose scales polarize light.
14. Cuttlefish have a total of eight arms and two tentacles.
Cuttlefish have eight arms that surround their mouth. These arms are shorter and are used for grasping food, exploring their surroundings, and interacting with other cuttlefish. In addition to the arms, cuttlefish have two longer retractable tentacles with small suction-cup-like structures at their ends. These tentacles are primarily used for capturing prey and bringing it to their mouth.
15. They use their ink to defend themselves.
Many marine species, such as sharks and larger fish, are known to eat cuttlefish, attracted by their soft, meaty bodies. However, cuttlefish have a defense strategy that involves producing ink. When faced with a potential threat, cuttlefish can release a cloud of cuttlefish ink into the water, creating a distraction and confusion for predators.
Just like the squid ink, this serves as a diversion, giving the cuttlefish valuable time to get away and escape from the immediate danger quickly. A specialized gland in the cuttlefish's body creates this ink, and the ink cloud can vary in color and intensity depending on the species.
Fun fact: Did you know that the sepia cuttlefish ink, while primarily used for defense, can also be used in cooking and has been the secret ingredient in many traditional dishes? Additionally, the sepia pigment was used for writing in ancient times.
16. They use cuttlebone for buoyancy control.
The cuttlebone inside cuttlefish is an internal structure rich in calcium carbonate. It is a natural calcium supplement for various animals, including birds, reptiles, chinchillas, shrimp, hermit crabs, and snails. Cuttlefish use the cuttlebone for buoyancy control, adjusting their position in the water by filling or releasing gas in their chamber.
17. They are not classified as endangered.
Some species are abundant and not considered threatened, while others may face varying degrees of concern. For example, the Common Cuttlefish is listed as "Least Concern," indicating it is not at significant risk of extinction. On the other hand, the Flamboyant Cuttlefish has a "Data Deficient" status due to limited available information.
The Giant Cuttlefish has experienced population declines in some regions, although the International Union has not assessed its overall status for Conservation of Nature (IUCN).
Climate change poses a significant risk to cuttlefish. Rising ocean temperatures and increasing ocean acidification directly impact their habitats and breeding cycles, disrupting their natural rhythms and survival strategies.
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Alves, D. C., Cristo, M., Sendão, J., & Borges, T. (2006). Diet of the cuttlefish Sepia officinalis (Cephalopoda: Sepiidae) off the south coast of Portugal (eastern Algarve). Journal of the Marine Biological Association of the United Kingdom, 86(2), 429–436.
Kling, G., & Schipp, R. (1987). Comparative ultrastructural and cytochemical analysis of the cephalopod systemic heart and its innervation. Experientia, 43(5), 502–511.
Payne, N. C., Snelling, E. P., Semmens, J. M., & Gillanders, B. M. (2013). Mechanisms of Population Structuring in Giant Australian Cuttlefish Sepia apama. PLOS ONE, 8(3), e58694.
Schnell, A. K., Boeckle, M., Rivera, M., Clayton, N. S., & Hanlon, R. T. (2021). Cuttlefish exert self-control in a delay of gratification task. Proceedings of the Royal Society B: Biological Sciences, 288(1946), 20203161.